CNC Class

instructables classes
CNC CLASS
5 Lessons Beginner Level
In this class, you’ll learn everything you need to know to design and create your own CNC cut
projects, whether or not you’ve got access to a CNC router. We'll cover cutting at panels for at-
pack furniture, carving complex 3D forms, desktop CNC mill operation, CNC router operation,
design principals and techniques, and how to get your designs out of the computer and onto a CNC
machine.
Ent e r a n I ns t ruct a ble s C ont e s t !
If you've used the skills you learned in this class to design something awesome, try writing an
instructable about it and entering one of our contests, like the Furniture Contest for a chance to win
some awesome prizes!
Class Author:
JON-A-TRON
Jonathan Odom is a professional designer with more than 10 years of experience in CNC design and fabrication. He has used
CNC machines for architectural installations, industrial design prototypes, furniture, and lots of other projects on Instructables.
His work has been exhibited locally and internationally, published online and in print, and is enjoyed by friends, family, collectors,
and clients.
CNC Class: Page 1

Lessons
Lesson 1: Tools and Materials for CNC

A list of tools, services, and materials for the class.
Lesson 2: Flat Pack Furniture

Designing flat-pack furniture in Fusion 360.
Lesson 3: Flat Pack Design Preparation

Prepping a flat-pack design for CNC cutting.
Lesson 4: CNC Router CAM Setup

Creating toolpaths for cutting flat-pack parts.
Lesson 5: CNC Router Operation

Setting up and running a CNC router.
CNC Class: Page 2

Lesson 1: Tools and Materials for CNC
ht t ps://player.vimeo.com/video/188201991?t it le=0&byline=0&port rait =0
In this class, you’ll learn everything you need to know to design and create
your own CNC cut projects, whether or not you’ve got access to a CNC router.
We’ll learn some useful 3D modeling techniques, how to create joinery, and
talk about equipment and materials.
CNC stands for Co m put e r Num e rica l Co nt ro l . Simply put, it is a machine
with a tool-holding head whose movements are controlled by a computer.
Laser cutters, water jets, and CNC routers are all CNC machines. 3D printers are
technically CNC machines as well, but they have additive tool heads (adding
layers of melted plastic) as opposed to subtractive ones like routers
(subtracting from stock by cutting or carving into it).
CNC machines are controlled using a very simple programming language
called G-Code. With a 3-axis CNC machine, the computer tells the head to
"move in the X axis 2.1 inches"... "move in the Y axis 1.3 inches"... etc.
This computer control allows you to quickly and accurately cut out a wide
variety of stock (wood, plastic, metal, etc.) in just about any shape you can
imagine. CNC machines can carve complex 3D shapes, cut 2.5D contours out of
panels, and even cut out fabric or leather with a drag-knife setup.
CNC allows you to create a design in your CAD software, create a CAM setup
(Computer Aided Manufacturing), and produce a physical copy of your design
very quickly. One of the added bene ts is that you can change your design and
update your CAM setup to improve on it. You can also produce multiple exact
copies of the same object.
CNC Class: Page 3

I think the CNC router is the most powerful DIY tool in the world. Although 3D
printers and laser cutters are great for making all kinds of things, they're very
limited when it comes to size and structure. With a CNC router and enough
plywood, you can literally make a house. I made this 9' tall semi-permanent
shelter for two campers using $250 worth of MDF, some exible metal aps,
wood screws, and a CNC router...
Ungloo, Joshua Tree, CA, 2008
P R O J EC T 2 : D i n i n g T a b l e + C ha i r s
To learn the subject, we'll focus on at-pack design by making a full-sized

dining table. We'll design it in Fusion 360, a free CAD modeling suite complete
with a sophisticated CAM environment. We'll make this project on the Shopbot
CNC Router, a machine shop tool that can be found in maker spaces
worldwide.
Flat-Pack Dining Table
Finally, we'll get some practice with more complex geometry by designing a
at-packed dining chair to go with the table. Since we're using CNC, we can
make as many copies as we want in no time!
Flat-Pack Dining Chair
Software
A ut o d e s k Fus i o n 3 6 0 (Fr e e )
This is a powerful 3D modeling platform that's easy to learn but has endless
potential. With it, you can design complex 3D objects for practically any kind of
fabrication, digital or otherwise.
CNC Class: Page 4

Click here to sign up for f re e as a Hobbyist / Enthusiast / Startup or as a
Student or Educator.
1. Follow one of the links above to download the app (don't use the App Store on
Mac).
2. Enter your email and download the free trial.
3. Install and setup a free Autodesk ID account.
4 . When you open Fusion, select the Tr i a l C o u n te r in the upper toolbar (it tells
you how many days are left on your trial).
5. In the next dialog box, select "R e g i s t e r f o r Fr e e Us e ".
6. S i g n up a s a S t a r t - Up o r En t hus i a s t (Free). You can also Sign up as a
S t ud e n t o r Ed uc a t o r (Free) if you're a student or educator at a registered
institution.
7. Select the "I accept Terms and Conditions" checkbox and click S ub mi t .
CNC Design & Fabrication Process
1 . D e s i g n + Mo d e l
CNC Class: Page 5

The rst step is to create and model your design in CAD (Computer Aided
Design). We'll do this in Fusion 360, which we'll introduce you to and provide
download links for in the next lesson.
When you're designing an object that you intend to cut out with a CNC
machine, it's very important to rst know the following:
1. What's the size of your CNC machine 's table ? The size of the table will limit the size of
the stock you can cut.
2. What's the size and thickne ss of your mate rial? You will always need to know this, but
it's particularly important when you're designing parts with joints that t together.
3. What's the le ngth and diame te r of your e nd mill? An end mill is a cutting tool kind of
like a drill bit or router bit that's speci cally designed for clean, precise cutting of
speci c materials.
When you start your design knowing these three things, you'll be able to make
smart choices about how to design the object.
We'll also get into pa ra me t e rs in the Fusion 360 design. Parameters are just
variables you can apply to any part of a model. In our case, we'll use them to
establish the thickness of the stock for the table and chair projects.
2 . C A M S e t up
CAM (Computer Aided Manufacturing) involves taking one or more 3D objects

and creating a G-Code tool path that will cut out or mill the parts as desired.
Another reason we're using Fusion 360 is that CAM is built into the software,
so all you have to do is switch from one workspace to another to work on the
CAM setup.
You'll also be able to change a design, then update the CAM setup to work
with the changes you've made. This makes it easy to experiment and improve
your designs as you cut out parts.
3 . C NC Ma c hi n e S e t up + O p e r a t i o n
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With your tool paths nished, you'll learn how to safely operate both a desktop
and full-size CNC machine for the best results in 2.5D cutting and 3D carving.
CNC Machines
O t he r Ma c hi n e C o. O t he r mi l l
Other Machine Co. makes a small, desktop CNC machine that I'll use in Lesson
5. It's made for PCB boards speci cally, but it's a fully functioning CNC mill
with a 2" maximum depth. It's great for small parts and a good option if you've
got limited space.
C a r b i d e 3 D S ha p e o k o
Carbide 3D makes the "most powerful, most hackable, most complete " CNC
machine in its class. This is a simple kit which you assemble yourself in about
an hour. The machine must be plugged into a Mac or PC in order to run. All
versions come with either a 1.25 HP Dewalt spindle or a Makita spindle. Fusion
360 includes a post-processor for these machines, so it's easy to make
toolpaths and run them on the machine with good results. It's got a 3" Z
travel, which is respectable for a machine of this size.
It comes in 3 versions:
Sha pe o ko 3
Cutting area: 16"x16”

Footprint: 28-1/2”W x 24 ”L x 16”H
Weight: 70 lbs
Price: Starting at $1099
Sha pe o ko XL
Cutting area: 16x33”

Footprint: 4 5”W x 24 ”L x 16”H
Weight: 100 lbs
Price: Starting at $14 99
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Sha pe o ko XXL

Footprint: 4 5”W x 4 0-1/2”L x 16”H
Weight: 14 5 lbs
In v e n t a b l e s X - C a r v e
The Inventables X-Carve is a great choice for makers with limited space and a
limited budget. It comes in 500 X 500 mm (19.5 X 19.5 in), 750 X 750 mm (29.5 X
29.5 in), and 1000 X 1000 mm (39 X 39 in) for $1,200, $1,350, and $1,460
respectively.
All models use a Dewalt router (which is easy replaceable) as the spindle and
have a 65 mm (2.5 in) Z depth which is more than enough for at pack projects
and relief sculptures.
The company claims a .075mm - .13mm accuracy resolution, which is really
impressive considering the price.
In short, if I were to own my own machine I would get the 1000 X 1000 version.
You can do a lot with 39" of width, and you can cut longer sheets if you
properly index and move the panels as demonstrated in this video.
S ho p b o t A l p ha
For this class, I'll be using the ShopBot Alpha to demonstrate the work in the
lessons. The ShopBot is a Computer Numerical Control router capable of
cutting 2D and 3D shapes in wood, foam, plastic, some non-ferrous metals,
and a variety of other materials. The ShopBot CNC machine I'm using in the
lesson is considered full-size and can handle 4’x8’ sheet goods. It is a PRSAlpha
96 48 equipped with Z-axis travel of 12” and a 24,000 RPM, 3 horsepower
Colombo spindle.
This machine can be found in maker-spaces worldwide such as Techshop.
Service Bureaus
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Yo u do n' t ne e d a CNC m a chine t o t a ke t his cla s s o r e v e n t o m a ke
CNC f a brica t e d pa rt s . S e rv ice bure a us a re a g re a t o pt io n if y o u
do n' t ha v e a cce s s t o a m a chine . He re a re a f e w t o cho o s e f ro m .
10 0 K G arages
100K Garages is a site that connects designers to fabricators. They have a huge
network of people who own CNC machines and can turn your designs into
parts, and they're located all over the world.
O pendes k
Opendesk is similar in that it connects you with designers and makers, but
they've also got a "Studio" section where you can post your design and have
people vote on it. If your design gets enough votes, they'll fabricated and sell
it and pay you commission!
End Mills
En d Mi l l f o r S ma l l - S c a l e C a r v i n g
For the desktop CNC carving project, a ball-nose 1/8" end mill is a good choice.
This type of end mill lets you get a smooth nish on a carving project because
the round shape helps you avoid the stepping e ect you'd get from a at
pro le tool.
Amazon: 1/8" Ball Nose End Mill

En d Mi l l f o r P l yw o o d C ut t i n g
To make a tool path, you have to know which end mill you're going to use. An
end mill is a kind of router bit with properties that make it better at cutting for
speci c applications.
In my experience, the do w ncut s pira l endmill is the best choice for at-
packed plywood furniture. The ute orientation gives you a clean top surface,
and the bottom surface is compressed against the bed. This gives you clean
cuts on both sides. The kerf does tend to get a bit gummed up, but you can
always pause the job and clean out the chips and sawdust.
O ns rud is a great resource for endmills, but you can buy common ones on
Amazon.
Amazon: 1/4" Downcut Spiral End Mill
CNC Class: Page 9

Other Tools
C l a mp s f o r W o r k - ho l d i n g a n d A s s e mb l y
I like the Irwin Quick Grip- it's very sturdy and easy to use. These are great for
holding material if you don't have another hold-down system and they're
crucial for sanding and assembly.
$17 Amazon: Irwin Quick Grip
Digit al Calipers
These are an absolute must. You have to know the exact thickness of your
material for any CNC project.
$17 Amazon: Electronic Digital Caliper
S o f t Ha mme r
You'll need these for assembling at-pack parts and for nudging large sheets
into place on a full-size machine.
$16 Amazon: Dead-Blow Hammer
S af et y Glas s es
I've seen parts get jammed in the tool and y across the room. ALWAYS
W EAR S AFE T Y GL AS S ES .
$11 Amazon: Safety Glasses
Wood and Plywood
My advice is to locally source your wood- it tends to be cheaper than ordering

online and you've probably got a mom-and-pop lumber yard you can support
no matter where you are.
P l yw o o d
I'm using 3/4" A-grade maple veneer plywood for the at-pack project. You can
use CDX if you want, but the A-grade stu is much nicer to work with and
requires less nishing work.
Ha r d w o o d
CNC Class: Page 10

I'm using Poplar for the carving project, but solid wood or plywood will work
for this one as well.
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Lesson 2: Flat Pack Furniture
This lesson will demonstrate a step-by-step method of designing a at-pack /

friction- t table for CNC fabrication.
I've been doing at-pack / friction t projects for more than 10 years. I've
learned a lot of tricks that I'm about to pass on to you, and if you stick with me
I think you'll learn some really useful concepts and techniques that will serve
you will with any kind of fabrication, especially CNC.
FL AT PA C K / FR I C T I O N FI T
You're going to design a table that's at-packed and friction- t. Fla t - pa ck

refers to its being made of interlocking at parts, and f rict io n- t means it
can be assembled so that the friction between the pieces will hold it together
without any fasteners.
The example in the lesson has 7 parts in total. Two legs, four sti eners, and one
table top. The sti eners provide lateral stability to keep the table from twisting
or wobbling.
The Fusion Interface
CNC Class: Page 12

Fusion 360 has a great Youtube channel with lots of helpful videos. If you're
the type of person who likes to learn software by going through every
function it can perform, this channel is a good place to start. The overview
here should get you pretty well oriented to the interface and give you an idea
of how the program works.
But before we dive into a full- edged 3D model, I'll quickly run through the
interface.
PRO T IP: Use a 3-button mouse! It's so much easier than using a trackpad.
1. A p p l i c a t i o n b a r : Access the Data Panel, le operations, save, undo and redo.

2. P r o l e a n d he l p : In Pro le, you can control your pro le and account settings,
or use the help menu to continue your learning or get help in troubleshooting.
3. T o o l b a r : Use the Toolbar to select the workspace you want to work in, and the
tool you want to use in the workspace selected.
4 . Vi e w C ub e : Use the ViewCube to orbit your design or view the design from
standard view positions.
5. B r o w s e r : The browser lists objects in your design. Use the browser to make
changes to objects and control visibility of objects.
6. C a n v a s a n d ma r k i n g me n u: Left click to select objects in the canvas (the
space where you make your models). Right-click to access the marking menu. The
marking menu contains frequently used commands in the wheel and all commands
in the over ow menu.
7. T i me l i n e : The timeline lists operations performed on your design. Right-click
operations in the timeline to make changes. Drag operations to change the order
they are calculated.
8. Na v i g a t i o n b a r a n d d i s p l a y s e t t i n g s : The navigation bar contains
commands used to zoom, pan, and orbit your design. The display settings control
the appearance of the interface and how designs are displayed in canvas.
CNC Class: Page 13

Sketch the Table Top Profile
Most things in Fusion are best made by creating 2D sketches, then turning
those sketches into 3D objects. For a round tabletop, that means drawing a 2D
circle, then extruding it to give it thickness.
C r e a t e C o mp o n e n t
A component is an encapsulated part that can have one or more 3D bodies or

2D sketches in it. You want each of the table parts to be its own component
because it will allow you to manipulate and manage the whole model more
easily.
Go to CREAT E > Ne w Co m po ne nt , and give the component a name like
"tabletop". Keep the default settings there (Empty Component) and click OK,
and you'll see that your new component has shown up in the Browser and that
it's activated. While it's activated, anything you make will be within this
component.
Creat e a Sket c h
Go to S KE T CH > Cre a t e Ske t ch , and click on the bottom plane of the

model space. This will bring you into the Sketch environment. The view will
change to the Top view.
For this sketch, all you'll need is a circle. Go to S KE T CH > Circle > Ce nt e r
D ia m e t e r Circle and click on the model origin as your start point.
Type in 42 for the diameter and you'll have a 42" (1066mm) Ø table top. Click
the St o p Ske t ch button on the upper right to leave the sketch environment.
CNC Class: Page 14

Create 3D Part / Use Parameters
M EA S U R E Y O U R P LY W O O D
Before you design anything, you need to know exactly what the thickness of
your plywood is. 3/4" (19mm) plywood is a nominal dimension, meaning the
actual thickness will vary a bit. T his ca n be a n inf uria t ing pro ble m if
y o u' re no t pre pa re d! Never make assumptions, always measure twice and
cut once.
You should always have a set of digital calipers on hand to measure the wood.
Close the jaws on the sheet as shown to get an exact measurement.
C R EAT E A T HI C K NES S PA R A M ET ER
Any time you're making at pack furniture, you almost certainly should use a
parametric thickness. In 3D modeling, parametric means that a variable has
been established that can be changed later, automatically changing any part
of the model that used the parameter.
Plywood thickness changes from batch to batch, even from the same supplier,
so if you use parameters, you can just change the parameter to adjust all of
the parts instead of doing it manually- t his w ill s a v e y o u ho urs o f w o rk!
To set a parameter, go to M O DIFY > Cha ng e Pa ra m e t e rs , click the g re e n

plus - s ig n next to Us e r Pa ra m e t e rs to create your thickness parameter.
1. Na me : The name you'll use to enter the parameter in any number eld. This should
be as short as possible because you'll be using it a lot, so pick "t" for thickne ss.
2. Un i t : Defaults to the units your le is working in, but you can use any unit you
want and it will automatically convert.
3. Exp r e s s i o n : This is the value in selected units of the thickness of your plywood.
This will be di erent for practically every batch of plywood, so use digital calipers
to measure your plywood to get an exact measurement. Mine is .76.
4 . C o mme n t : This is optional, but if you've got a really complicated model it's a
good idea to make a note about what the parameter is for here.
CNC Class: Page 15

EX T R U D E S K ET C H
Now that you've got your parameter set, you can extrude the tabletop pro le
sketch you made previously. Go to CREAT E > Ext rude , select the circle
sketch pro le, then type " t " in the D is t a nce eld in the EXTRUDE dialog that
comes up. O pe ra t io n should be set to Ne w Co m po ne nt . Click OK and
you'll have a tabletop component.
You can go back to M O DIFY > Cha ng e Pa ra m e t e rs and change the

parameter value to see the thickness of the table change.
Move Table Top Component
The tabletop was made on the oor of the model, so we'll need to move it to
the proper height. Click on the tabletop, then right-click and select M o v e
from the popup dialog.
You'll get a manipulator that will let you move and rotate the part. Drag the
Up a rro w to move the table up, then enter 28 " (710 m m ) - that's the
standard underside height for a dining table.
Sketch Leg Profile
C R EAT E A S K ET C H
With your tabletop in place, it's time to draw the rst pair of table legs. To do
this, like pretty much everything else, start with S KE T CH > Cre a t e Ske t ch.
Pick either the Front or Side plane to sketch in. You'll get a warning about
parts having been moved. Be sure to click Ca pt ure Po s it io n. If you click
"Continue", the tabletop will move back to the bottom plane.
CNC Class: Page 16

P R O J EC T T A B L E P R O FI L E
Remember that when you're in the Sketch environment, you're only creating
lines. Parts of the 3D objects and other sketches that might be visible can
sometimes be snapped to, but they don't represent lines in the sketch you're
working in.
You're going to need the line representing the underside of the tabletop to
make the pro le of the legs. To get this, go to S KE T CH > Pro je ct / Include
> Pro je ct . As with any tool, hit ES C APE to get out of it.
Click on the underside edge of the tabletop, and you'll get a pink line with
points at each end. Click O K to exit the Project tool.
C R EAT E L EG P R O FI L E B O U ND A R Y
With the projected line, you can now make a rectangle to create a boundary
for the pro le of the legs. You could always just draw the legs however you
like, but I like to start with boundaries that relate to other objects as a way to
control the geometry. To make a boundary, just go to S KE T CH > Line and
complete the rectangle with the projected table line as the top. You could also
use the Re ct a ng le tool in the S KE T CH menu.
Table legs should always touch the oor so that there's a signi cant gap
between the foot and the edge of the table as seen from above. Did you ever
notice how your kitchen cabinets have a kick underneath them? This recess lets
you belly-up to the countertop without stubbing your toes.
The idea is the same for tables. Work backwards from the rectangle you just
made to create this recess. Go to S KE T CH > O s e t , unchenck Cha in
S e le ct io n, and select one of the vertical lines. This will o set the line parallel
to the original by a distance you specify. A 4" (100mm) o set will give you
enough room to avoid stubbing your toes without sacri cing too much
stability. Notice by pulling the arrow that you will probably need to enter a
ne g a t iv e v a lue since you're o setting to the inside of the rectangle.
Think of this line as the outermost possible distance the leg can go from the
center of the table.
D R AW L EG P R O FI L E
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Now that you have your boundary complete on the left side, you can start
drawing your table leg pro le. To make them slanted, draw a Line from the
bottom point of the line you just o set and move the other point so that it
makes an angle. An 85º angle (meaning 5º o of the vertical line) works well
for style and stability. You can make this angle any arbitrary angle that's close
to 5º, but if you want to be precise, hit the Ta b key and enter the degree in
the degree box, then hit Ta b again to lock it. You'll see that you can now drag
the mouse to make the line longer or move it around the origin, but the angle
will be locked. Click the other end of the line when you're satis ed.
This line will be the outermost edge of the table leg on the left-hand side. To
give the leg thickness, go to S KE T CH > O s e t and o set the line you just
drew. 3" (76mm) is about the minimum that will be stable with o -the-shelf
soft plywood in my experience. When you've dragged the arrow in the correct
direction, give it a value of 3" (76mm) and click O K .
The pair of table legs is going to be a single, connected part, so it's going to
need depth to give it stability. To do this, just go to S KE T CH > O s e t and
o set the line you projected from the underside of the table. This should also
be at least 3" (76mm), but don't go too much deeper or you'll hit your knees on
it!
At this point, the leg pro le is nished aside from all the crossing lines.
Remember, a 3D object comes from an extruded sketch (just like you did with
the tabletop), so you'll need a closed pro le for the table legs. You can clean
up the crossing lines by going to S KE T CH > Trim and clicking on the line
segments that you don't need. As with any tool, hit ES C APE to get out of it.
With your leg pro le nished on one side, you can avoid drawing it again on
the other side by mirroring it. To mirror, you'll need a centerline. Go to S KE T CH
> Line and draw a line down the center of the leg pro le. You'll see a triangle
symbol when you're snapping to the center of the top line. It's important that
this line is vertical and centered on the drawing.
To mirror the leg pro le to the other side, go to S KE T CH > M irro r, then
select the lines that make up the leg pro le on the left side. Click on M irro r
Line , then select the centerline you made in the last step. You should see a
preview that gives you a symmetrical pair of legs. Click O K , and you should
have all the lines you need to make your 3D part.
CNC Class: Page 18

If you use the Trim tool again to clean up the pro le, you should see a closed
pro le like the one shown below. This is what you'll use to create the 3D leg
part. Click St o p Ske t ch to get back to the modeling environment.
Create First Leg
With your leg pro le complete, you can now make a 3D part. You can go to
CREAT E > Cre a t e Co m po ne nt to create an Em pt y component to work in.
This will save you having to deal with the other parts of the model- you'll be in
the activated component you just made, which will gray-out the other parts as
shown below.
Go to S KE T CH > Ext rude and click on both of the pro les separated by the
mirror line. If you pull on the arrow, you'll see that the 3D part will be extruded
in one direction only. You want the table leg part to be aligned with the center
of the table, so you'll need to do an extrusion that does in both directions and
still has the t thickness parameter.
To do this, set D ire ct io n t o Sy m m e t ric, and D is t a nce t o t /2. This will

extrude the part in both directions by a value of 1/2 t , which totals t .
You should end up with a new 3D part with a thickness of your t parameter
that's aligned to the center of the tabletop.
Create Tab Feature
CNC Class: Page 19

This is a at-pack / friction- t design, so we're going to need some interlocking
features- tabs and slots. The top of the table leg part will slot into the
underside of the table with a tab.
C R EAT E S K ET C H
To create a tab, go to S KE T CH > Cre a t e and select the f ro nt f a ce o f t he

t a ble le g as your starting plane.
The tab should be centered on the top part and have gaps on the sides- if it's
too wide it'll be too di cult to build. Go to S KE T CH > Line and draw this gap
at about 6" (150mm) along the top edge.
Draw another 6" line on the other side, then draw a tab that looks about half
way through the depth of the table top. Make sure all the angles are 90º! The
cursor should snap to 90º automatically.
U S E PA R A M ET ER FO R T A B HEI G HT
Remember, all your parts are parametric, meaning you need to make sure
they'll update properly when you change a material thickness. The tab needs
to be exactly half as deep as the thickness of the material. To make this work in
a sketch, go to S KE T CH > D im e ns io n , and click o n t he t o p line o f t he
le g pa rt a nd t he t o p line o f t he t a b pa rt . A real dimension will show
up, but you'll need to change it to t /2. This will give you a tab that's 1/2 the
thickness of your material and will update when you change the parameter. If
the parameter was entered properly into the dimension, you should see " f x: "
then a number value. In my case, it's 0.38" because that's 1/2 of .76".
Click St o p Ske t ch to get back to the modeling environment.
EX T R U D E T A B
Go to CREAT E > Ext rude and extrude the body back to meet the back face
of the leg part. You should enter t for the D is t a nce here as well to make sure
the parameters are being used everywhere. O pe ra t io n should be set to Jo in
by default.
Use Leg Tabs to Create Pocket
CNC Class: Page 20

Now that your leg is done, click the circle next to the To p- Le v e l
Co m po ne nt in the Bro w s e r. This will be the rst item in the list. At this
point you should have two components under the top level- the leg and the
tabletop.
C O P Y B O D Y T O NEW C O M P O NENT
Next, you'll need to make a copy of the table leg for the second leg
component. If you copy the component in the browser, you'll have two copies
that are connected, meaning if you change one the other will change to
match. If you copy the b o d y within that component, you'll get a new,
independent copy of the leg in that state.
Click the a rro w next to the leg component in the browser, then click the
a rro w next to B o die s in that component. Rig ht - Click on the body, then
Co py + Pa s t e it. You'll now have a new body in the B o die s folder under the
To p- Le v e l Co m po ne nt in the Bro w s e r .
Rig ht - click on the body you just made, then select Cre a t e Co m po ne nt s
f ro m B o die s . You'll get a new component that you should name something
like "leg 2".
R O T AT E L EG
Rig ht - click on the new component, then select M o v e . Move the Ro t a t io n

Arc on the M a nipula t o r to rotate the leg by 9 0 º . You'll now have two legs
at a right-angle to each other.
C R EAT E P O C K ET I N T A B L ET O P
Now that the leg components are in place, you can make the pocket in the
tabletop. Go to CREAT E > Co m bine , and select the tabletop as the Ta rg e t
B o dy. For To o l B o die s , select both of the table legs, and be sure that
Ke e p To o ls is checked- if it's unchecked, both of your legs will disappear.
If you turn o the leg components in the Bro w s e r (click the lig ht bulb next
to them) You should now see that your table has a pocket on its underside.
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Create Interlocking Features
The next step will be to create an interlocking feature between the legs. The
trick here is to make a tab on each leg that's half-way through the depth of
the top part. This will keep the legs in place but won't sacri ce too much in the
way of stability.
C R EAT E S K ET C H FO R S L O T
Start by creating a Ske t ch on the face of one of the table legs.
Go to S KE T CH > Pro je ct / Include > Pro je ct and select B o die s in the

S e le ct io n Filt e r. Click on the leg part that's crossing the sketch you're
drawing in, and you'll get two lines that match the thickness of the leg.
To draw the cutout, draw a Re ct a ng le from a top point to the intersection

between the lines on the opposite side of the bottom.
With that in place, b ise c t the rectangle with a Line from midpoint to
midpoint (the triangle icon means you're snapping to a midpoint). Click St o p
Ske t ch to get back to the modeling environment.
EX T R U D E T A B C U T O U T
Turn o the crossing table leg component in the Bro w s e r, then go to

CREAT E > Ext rude and select the top part of the tab sketch. Pull the a rro w
into the component so that it cuts through, and you'll see that this will be a
negative value. Enter t for the D is t a nce , and leave O pe ra t io n on Cut .
S U B T R A C T T A B C U T O U T FR O M O T HER L EG
There's no need to repeat all these steps for the other leg. Go to M O DIFY >
Co m bine , select the leg without the cut as the Ta rg e t B o dy, then select
the leg with the cutout as the To o l B o dy. Be sure to have Ke e p To o ls
checked.
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You should now have one leg with a cut at the top and one leg with a cut at
the bottom.
Draw Stiffener Profile
This table would stand at it is, but it would wobble like craz y. There's nothing
to keep the legs from bending against the short dimension so you would
basically get a twisting motion if you were to push on the tabletop. To prevent
this, we'll need some sti eners.
Go to CREAT E > Ne w Co m po ne nt to make an empty component to work
in. Next, create a Ske t ch on one of the leg faces. You'll need a centerline for
this part, so just draw a Line roughly down the center of the leg.
In the Ske t ch Pa lle t t e on the right side of the canvas (it might be nested, if
so just click on the double arrow), click on Pa ra lle l under Co ns t ra int . Click
one of the table leg lines rs t , then click the centerline you drew before. This
will allow the centerline to move but will keep it parallel to the leg line. You
should see a couple of double line graphics showing you they're constrained.
To make sure the line is centered, go to S KE T CH > D im e ns io n, and click the

leg line and centerline. Enter a value that's 1/2 of the width of the leg, which is
1.5" (38mm) if the leg width is 3" (76mm) as shown.
This line represents the center of the sti ener from the side. To give it
thickness, go to S KE T CH > O s e t and o set it by a factor of t /2 in both
directions.
Draw a Line from the intersection at the top of the outer line so that it meets
the inner line at a 90º angle. This will be the top of the sti ener.
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Next, O s e t the top line by 14" (355mm) to make the bottom edge of the
sti ener. It needs to be at least this deep to keep the table from wobbling.
You should now have a closed rectangular pro le, select it to be sure there
aren't any gaps in the lines.
Create Stiffener Component
C R EAT E A 3 D B O D Y
Use the side pro le you just made to Ext rude the part. Be sure to use the t
parameter and extrude it in the correct direction. The O pe ra t io n should be
Ne w B o dy.
When that's done, Ext rude both faces of the new body by a D is t a nce of 3"
(76 m m ) .
C R EAT E C U T O U T S K ET C H
Like the table legs, this sti ener part will need a slot to interlock it with the
legs. To do this, create a Ske t ch on the face of the table leg, then use the
Pro je ct tool. Make sure B o die s is selected in the S e le ct io n Filt e r, then
project the side face of the sti ener to create a rectangle that's constrained to
the shape.
Draw a Line connecting the midpoints of both of the long lines that make up
the rectangle. This will give you a pro le you can use to create a cut in the
sti ener that's half way down its length.
EX T R U D E C U T O U T
Use the CREAT E > Ext rude tool to select the cutout pro le. If the sti ener is
turned on in the browser, you probably won't be able to select the pro le you
want. Hit the do w n a rro w to cycle through the possible selections with the
cursor hovering over the pro le until the pro le is highlighted, then click on it.
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Extrude this pro le into the sti ener using your t parameter. This should give
you a cutout that's centered on the piece.
C R EAT E T A P ER ED P R O FI L E
The sti ener needs to be tapered at the end to keep knees from knocking into
it, it should also be narrower at the top. To make this pro le, create a Ske t ch
on the face of the sti ener.
Draw a Line from the midpoint of the bottom line to give yourself a top point
to aim for.
O s e t the line on the side of the cutout by a distance of - t . Be sure Cha in

S e le ct io n is o .
Draw a diagonal Line connecting the two points to create a tapered pro le.
Draw a vertical Line at the midpoint of the cutout to give yourself a mirror
reference.
Go to S KE T CH > M irro r, select the diagonal line under O bje ct s and the
vertical line for the M irro r Line . This should give you a symmetrical tapered
pro le.
With your pro les nished, go to CREAT E > Ext rude and select the pro les
you want to cut out of the sti ener. Use the t parameter for the thickness here
as well.
Multiply Stiffeners and Create Interlocks
M U LT I P LY S T I FFENER S
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Now that you've got a usable sti ener, it's time to copy it in place at each of the
four legs. To do this, go to
CREAT E > Pa t t e rn > Circula r Pa t t e rn.
Set Pa t t e rn Ty pe to Co m po ne nt B o die s , select the sti ener under

O bje ct s , select the model up a xis under Axis , and set the Q ua nt it y to
4 . This should give you four sti eners in the correct place at each leg.
C R EAT E I NT ER L O C K I NG C U T S
Now it's time to cut the pro les of the sti eners out of the legs so they
interlock. To do this, go to M O DIFY > Co m bine , select one of the table legs
as Ta rg e t B o dy, then select the two corresponding sti eners as To o l
B o die s . Be sure to have Ke e p To o ls checked or your sti eners will
disappear. Repeat this step with the other leg component.
This will leave behind a small wedge at the top of the cutout, so just select
those faces and extrude them so that they cut all the way through the top of
the leg.
When you're done, the legs and sti eners should look like the picture below.
Fillet Sharp Corners
Sharp corners tend to split and chip easily, they're sharp to the touch, and, in
my opinion, they don't look as nice as rounded corners. To round o the
corners, go to M O DIFY > Fille t , and select the edges of the legs and
sti eners to llet them. You can do multiple parts at once, but in the video,
you'll see that I did a few di erent llet radii for di erent parts. The tapered
points of the sti eners should be about a .25" (3mm) radius to keep them from
being shortened too much. You'll see that when you llet the edges on one of
the sti eners, all the other ones will change automatically, since they're all
copeis of each other.
CNC Class: Page 26
Recap
We covered quite a lot in this lesson. Give yourself a hand if you stuck with it
and modeled something!
Your nished table should look something like this:
Did you design a table or something similar?
CNC Class: Page 27

Lesson 3: Flat Pack Design Preparation
The table model provided here is designed so that all the pieces will t within a
standard 4'X8' sheet of plywood. The rst step in the CAM process will be to
make copies of all the pieces and place them in a layout that will t on the bed.
For this lesson, you can either use the model provided or use the one you
designed in the Table Design lesson.
caption
CNC Class: Page 28

Table Model
If you skipped the table design lesson, I've provided the attached table model
as an example you can use to follow along with the CAM process.
FL AT PA C K / FR I C T I O N FI T
This table is designed to be at packed and friction t. Fla t pa ck refers to its

being made of interlocking at parts, and f rict io n t means it can be
assembled so that the friction between the pieces will hold it together without
any fasteners.
The table has 7 parts in total. Two legs, four sti eners, and one table top. The
sti eners provide lateral stability to keep the table from twisting or wobbling.
PA R A M ET R I C T HI C K NES S
This model has also been designed using a parametric thickness. In 3D

modeling, parametric means that a variable has been established that can be
changed later, automatically changing any part of the model that used the
parameter.
This model has a single parameter called " t " which is set to a value of .76 in.
The cutouts for the interlocking parts and the pockets were all created using
this parameter, so if you change this value to anything between about .7 in
and .8 in, it should update everything without any problems.
To learn more about the concept, go back to **Lesson 5
U P L O A D T HE M O D EL
1. Download the F3D le attached here.

2. Open Fusion, open the Da t a Pa ne l by clicking the Grid icon on the upper
left.
3. Click the Ne w Pro je ct button and create a project with a unique name.
4. Click the Uplo a d button at the top of the Da t a Pa ne l.
5. Drag the table le you previously downloaded into the window and click
Uplo a d . The table design will now be in the cloud along with all your other
Fusion les.
CNC Class: Page 29

https://www.instructables.com/ORIG/FX4/9LSR/IUHMT3R8/FX49LSRIUHMT3R8.f3d
… View in 3D Download
Create Part Layout
In Fusion 360 you can create a CAM setup on any object in the model. That is
to say if you wanted to, you could create a bunch of separate toolpaths on all
the parts and run them separately on a CNC machine. This isn't really e cient
for a project like the table. If you were to run a bunch of separate les, you'd
have to set set the X and Y origin of each part which would waste time and
probably material.
The best way to limit the amount of material wasted and save time is to make
copies of the parts and align them all to the oor of the model environment.
That way, you can run only two toolpaths (one pocket and one contour) and
ensure that your parts will t on the bed without too much wasted material.
Follow these steps and you'll be ready to make your toolpaths.
CREAT E A S HEE T BO UNDARY: To make sure your parts will t on the bed,
rst sketch a sheet boundary.
Go to S K ET C H > C r e a t e S k e t c h , then click on the " oor" plane of
the model space on the origin. If you get a "Some components have been
moved" warning, be sure to click C a p t ur e P o s i t i o n .
Next, go to S K ET C H > R e c t a n g l e and click the model origin. My sheet
is 4 8" X 96", so I type "4 8 " in the rst eld, hit T A B , then type "9 6 " in the
next eld.
Hit ENT ER to leave the rectangle tool, then click S t o p S k e t c h on the
toolbar to leave the sketch environment.
CREAT E CO PIES O F PART S: To create the part layout, you'll need to make
copies of the parts. This is a preferable to just moving the parts that are
already in the model because you might want to change your design later, and
the best way to do that is usually to do it while the table is assembled. If you
change one copy of a component, all other copies will automatically update.
Select all the components in the B r o w s e r , ri g ht - c l i c k > C o p y, then
ri g ht - c l i c k > P a s t e .
Turn o the original components by clicking the Li g ht b ul b next to each
one in the B r o w s e r.
CNC Class: Page 30

ALIGN PART S T O S HEE T S KE T CH: It's v e ry im po rt a nt to make sure
that all the parts are aligned to the same plane. If they aren't you can get all
kinds of problems down the road when you're creating your CAM setup.
Go to M O D I FY > A l i g n , click on the tabletop, then click on the
sketch. The pockets need to face up, so you may need to click the Fl i p
icon to ip the table the right way.
Repeat this step on every part of the table, ensuring that they're all ipped
as necessary so that they are all aligned to the same plane.
Nesting
In order to ensure that the parts have ample space between them for the tool
to cut, and that the minimum amount of material is wasted, you'll now do
what's called "nesting".
1. Click the T O P face on the Vi e w C ub e in the upper right corner. Next,
c l i c k - a n d - d r a g the parts around to get a general layout that looks
reasonable.
2. To rotate, r i g ht - c l i c k on any part in the B r o w s e r and select M O VE
from the drop-down menu. C l i c k - a n d - d r a g the arcs to rotate the
parts, and c l i c k - a n d - d r a g the square to move the parts in 2
dimensions.
3. Make sure the manipulator is aligned with the XYZ axes of the model
before rotating. The sti eners in my model have a weird orientation
because they were made in a plane that wasn't squared to the world origin.
To x this, click the S e t P i v o t icon, click anywhere on the part's top
face, then click the green checkbox in the M O VE window.You will now
have a properly aligned manipulator that you can use to rotate.
4 . Once the parts have the right rotation, move them around so that you
don't waste too much material, but leave about 1" between the parts to
give the tool some space to move around.
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Corner Treatment
I NS I D E VS . O U T S I D E C O R NER S
Corners have one simple rule in CNC: O ut sid e c o rn e rs c a n b e sh a rp,

in sid e c o rn e rs must b e ro un d e d . Since a round end mill is doing the
cutting, the radius of any inside corner will always match the radius of the end
mill. Sharp outside corners are easy, but there's no way to get sharp inside
corners with an end mill on a 3-Axis CNC.
Because of this universal fact, you cannot leave rectangular geometry as-is
after designing a at pack object and t the parts together as desired.
Of course, you could always chisel out the corners or use a le, but if you want
to quickly and cleanly assemble the project, there are a few tricks listed below.
O U T S I D E FI L L ET S
This corner treatment allows for a ush connection between the parts because
the end mill travels outside the corner by a distance that's equal to the radius
of the bit, allowing the end of each cut to sit ush against the other. This kind
of joint works well structurally speaking, but the llet is visible after the parts
are assembled.
I NS I D E FI L L ET S
the end mill travels outside the corner by a distance that's equal to the radius
of the bit, allowing the end of each cut to sit ush against the other. The
di erence is that the llet is cut into the short end of the cut. This kind of joint
works well structurally speaking and is inv is ible once the parts are
assembled.
Inside llets can be a bad idea if the material is too thin as compared to the
end mill. For example, if you were to use a 5/16" end mill with a 3/4" piece of
plywood, this type of llet would leave you with a 1/8" at spot on the inside of
the corner, which would probably just get broken o with soft plywood.
D O G B O NE FI L L ET S
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the end mill travels outside the corner at an angle so that the cut is made
equally on each leg of the cutout. Let material is cut with this method, it can
be done automatically using a script, and the llet is less conspicuous than an
outside llet would be. I pretty much exclusively use inside llets because
they're invisible, but doing doggone llets with a script is de nitely a time
saver.
Here's a link to a Fusion 360 add-in complete with installation instructions if
you want to go this route: https://github.com/caseycrogers/Dogbone
Create Fillets
For this project, inside llets are the best choice. With 3/4" piece of plywood and
a 1/4" end mill, there will be a 1/4" wide at spot at the end of each cut, which
will be ne for our purposes. Here are the steps:
CREAT E A S KE T CH: Go to S KE T CH > Cre a t e Ske t ch and click on the the
side of the table top that's facing up in the model.
DRAW CIRCLES: Zoom in on the rectangular ends of the pocket, go to

S KE T CH > Circle > 2- Po int Circle , click one of the points on the
rectangular end, then ho v e r over the other point on the rectangular end-
this will ensure that the circle is aligned properly. Type the diameter of the tool
(.25), then hit ENT ER. This will create a circle with a .25" diameter that's
attached to the side of the pocket. Re pe a t this step on every inside corner of
the pocket.
NO T E: Do not pattern or copy / paste these circles to save time. The circles need
to be constrained to the ends of the pockets to allow for changing the overall
thickness of the material later if necessary.
NO T E: The diameter of the llets will depend on your end mill. Make sure you're
using the right number here!
EX T RUDE FILLE T S: Click on Stop Sketch, then go to CREAT E > Ext rude .
Select the pro le made by each circle, then for the extrusion distance type "-
t/2".
CNC Class: Page 33

" t " is the thickness parameter that was used to set the thickness of all the parts.
The thickness parameter is set to 0.76 in, so t/2 = .38 in.
T ES T T HICKNES S PARAM E T ER: To ensure that the llets are properly

constrained to all the corners, change the parameter thickness and take a look
at the llets. Go to M O DIFY > Cha ng e Pa ra m e t e rs and double-click on
the number under Expression in the User Parameter " t " . Change this to
something noticeably bigger like 1 in.If the llets were drawn properly in the
sketch, they should still be aligned to the ends of each of the pocket's inside
corners, and the depth of the pocket should now be .5 in with the llets going
all the way to the oor of the pocket. Undo a nd Re do this change a couple
of times to see the thickness change.
Parameters are crucial to at pack projects like this because plywood comes in
so many di erent thicknesses. It's almost never .75" when it's nominally called
3/4" plywood, and one batch will often di er from the last even from the same
supplier.
REPEAT AS REQ UIRED: All of the inside corners of the design are going to
need llets in order for the table to t together without any gaps. Repeat
these steps on the rest of the parts and use the " t " parameter to ensure that
all of the llets will have full depth when parameters change
Finally, go to the Bro w s e r, hide the copies of the table parts that are at on
the oor, and s ho w the components for the assembled table. Look around at
the joints to make sure none of the llets are showing up.
Recap
In this lesson, you learned how to create nested layouts of at pack parts to
minimize material waste and save time. You learned how to manually create
lleted corners that are controlled by parameters, and you got a link to a
plugin that can create doggone llets automatically.
CNC Class: Page 34

Lesson 4: CNC Router CAM Setup
Now that your design is nished, it's time to get into the CAM environment.
CAM stands for Computer Aided Manufacturing- it's the process of translating
the design into instructions that the CNC router can use. The process breaks
down like this.
1. Cre a t e M a chining S e t up
In this part of the process, we'll set up the general parameters for our
machining operations. This includes width, length, and thickness of the
material as well as X,Y, and Z coordinates.
2. Cre a t e Po cke t To o l Pa t hs
The pockets on the underside of the table top will be the rst cuts you
make. It's good practice to do all the smaller cuts and drilled holes before
the main contour cuts because they're less risk of pieces getting pushed
out of place.
3. Cre a t e Co nt o ur To o l Pa t hs
With all the pockets nished, you'll create a tool path to cut out the
pro les of all the table pieces. You'll also learn about creating tabs to keep
the pieces in place while the router is cutting.
4 . Po s t Pro ce s s
With all the toolpaths nished, you'll learn how to post-process the data
into a format that a CNC machine can read.
Create Machining Setup
CNC Class: Page 35

The rst step in creating tool paths is creating a machining setup.

To create a machining setup, switch the workspace from M O DEL to C AM .
You'll see the toolbar change at the top of the screen with a new set of
options.
1. CREAT E NE W S E T UP: Next, click the Ne w S e t up icon under the S E T UP
menu. In this menu, you'll set the X,Y, and Z coordinates and establish the
dimensions of the stock to be cut.
2. S E T W CS O RIENTAT IO N: You should see a yellow box appear around the

parts that are visible on the canvas. The Work Coordinate System (WCS) will
also appear as an XYZ axis. Z needs to be the up-axis from this point of view, so
if you click on the arm of the Z axis, then click on any vertical line that's visible
in the model, Z will become the up-axis. The Y axis should point along the
short side of the rectangle (away from the FRO NT plane on the Vie w Cube )
and the X axis should point along the long side of the rectangle (away from
the S IDE plane on the Vie w Cube ). This WCS orientation will be consistent
with the coordinates on the Shopbot.
The WCS origin should be set to the bottom-left corner of the stock boundary
so that the axis arrows point along each edge of the stock. Click the white ball
on the WCS origin, then click the ball on the bottom left corner of the stock
boundary. This will move the WCS to that point.
3. S E T S T O CK BO UNDARY: Next, click on the St o ck tab in the Setup

window. The defaults leave a .04" o set on the top and sides of the parts. Set
the St o ck To p O s e t to 0" so that the thickness is exactly that of the
plywood panel. Changing the St o ck Side O s e t to 1" will give you a 1" wide
margin around the perimeter of the parts. This is a good way to make sure
your parts will t on the 48" X 96" plywood sheet with enough material to
spare around the edges.
Click O K , and you should have a new setup in the browser.
Choosing End Mills
To make a tool path, you have to know which end mill you're going to use. An
end mill is a kind of router bit with properties that make it better at cutting for
speci c applications. Here's a breakdown of the most common kinds of end
mills. Here are some key words to pay attention to.
CNC Class: Page 36
1. S ha f t D i a me t e r : The shaft diameter describes the width of the cut made by
the end mill. Common imperial shaft diameters range from 1/64 " Ø to 1 1/2" Ø with
steps of 1/64 " in-between. For the table, we'll stick with a 1/4 " shaft diameter to
keep things simple.
2. Fl ut e : The ute is the sharp edge of the end mill. An end mill commonly has one,
two, or four utes, but there is a wide variety to choose from. Flutes can be
straight, meaning they're parallel to the length of the end mill shaft, or they can
have a spiral pro le along the length of the shaft.
3. P r o l e : The pro le of the end mill is the shape of the pro le of the bit looking at
it from the side. There are many di erent kinds of pro les, but the most common
are ball-nose and at.
4 . C ut D i r e c t i o n : There are upcut, downcut, and compression cut end mills,
which I'll describe below.
The downcut spiral end mill has a ute that's oriented so that the cutting edge
pushes the material down as it cuts. This end mill results in a very clean top
surface with plywood because the veneer is cut in a downward motion.
However, since the end mill pushes the chips down, they tend to get
compressed, which can result in burning and sticking when cutting plywood.
When cutting aluminum, these end mills can actually cause heat welding to
occur.
The type of end mill is best suited for thinner materials like 1/4" - 1/2" since
there is less space for the chips to be compressed.
The upcut spiral bit does the opposite of the downcut spiral. The cutting edge
of the ute is oriented up against the material so the chips are ejected,
preventing burning. When cutting all the way through, it results in a clean cut
on the bottom of the material, but also has a tendency to lift the material up.
Another downside to this end mill is that it tends to delaminate the top of the
material.
Compression spiral bits are a combination of upcut and downcut bits. The
lower third of the bit has an upcut orientation, and the upper two thirds have
a downcut orientation. This end mill results in clean cuts on the top and
bottom of the material while avoiding the burning and lifting issues of
downcut and upcut bits. The catch is this: you have to cut full depth for it to
work e ectively, and you have to ramp your cuts.
CNC Class: Page 37

The smaller the shaft diameter, the more it's a ected by stress. The general
rule of thumb is that the depth of the cut remains 1/2 of the diameter of the
tool. Of course, most makers push those limits, but that rule gives you a good
picture of the limitations of the end mills. The denser the material, the more
force is ghting against the end mill as it cuts, and give enough force the end
mill will break.
In my experience, if you're cutting 3/4" plywood, a compression spiral bit
should be at least 1/2" Ø. This is great if you're going to go back and do a nish
tool path with a 1/4" bit, but if you're only doing one project at a time and
want to keep it simple, it's best to keep it simple and use a 1/4" bit.
T he B o t t o m Li n e
If you're not doing production runs of a project, it's okay to take your time and
stick with a smaller diameter bit. In my experience, the do w ncut s pira l
endmill is the best choice for at-packed plywood furniture. The ute
orientation gives you a clean top surface, and the bottom surface is
compressed against the bed. This gives you clean cuts on both sides. The kerf
does tend to get a bit gummed up, but you can always pause the job and
clean out the chips and sawdust.
Pocket Clearing Toolpath
ht t ps://player.vimeo.com/video/19064 0520?t it le=0&byline=0&port rait =0
With the setup nished and your end mill chosen, you're ready to make your
rst toolpath. The pocket should be done before any of the other cuts because
as contours are cut out, the parts become less stable. Go to 3D > Po cke t
Cle a ring in the toolbar to create a pocket toolpath.
The rst tab is where you'll set up all the tool settings. First, go to To o l >
S e le ct and choose a generic at 1/4" end mill from the list. There is a button
on the upper left side of this window that lets you lter by end mill type. This
generic tool will give you a starting point. Next, you'll set the feeds and speeds.
When you're running a CNC mill, it's important to have the proper settings.
The basic settings can be summed up in terms of "feeds and speeds".
FEED S + S P EED S
You will see lots of variables in the Tool tab of the Toolpath window, but I want
you to pay close attention to just these two when you're getting started in
CNC:
CNC Class: Page 38

1. Fe e d r a t e : The distance the spindle moves relative to the time it takes to move
along the workpiece.
Units are distance / time , usually i n / mi n or mm/ mi n .
2. S p i n d l e S p e e d : The rotational speed of the spindle.

Units are re volutions pe r minute or R P M .
All of the other variables (Cutting Feedrate, Feed Per Tooth, etc.) will update
automatically when you adjust these two. The goal here is to optimize the
feeds and speeds so that your work is cut as quickly as possible without
breaking the end mill.
If the feedrate is fast and the spindle speed is too slow, the end mill will break
under the lateral pressure:
If the feedrate is slow and the spindle speed is faster than it needs to be, there
will be little risk of breaking the end mill, but the job will take longer than it
needs to:
What you want is the Goldilocks zone: a spindle speed fast enough to cut
easily and a feedrate that's as fast as possible without risking too much lateral
strain:
Of course, the ha rdne s s o f t he m a t e ria l plays a major role in the proper

feeds and speeds. Metals needs slower spindle speeds to avoid overheating,
for example. Rigid foam is so soft that you can practically crank up the
feedrate to full tilt without worrying about breaking an end mill. Soft wood
will be somewhere between these two extremes.
Tool manufacturers will have their own recommendations for their tools to
make this step a bit easier. The numbers below are based on the following tool
by Onsrud:
1/4" 2 Flute Downcut Spiral #57-910
Chip Load Recommendations by Manufacturer
Geometry
CNC Class: Page 39
Next, click on the G e o m e t ry tab. This tab is where all the settings for the
geometry to be can can be found. For our purposes, the defaults don't need to
be changed. Click the pro le at the bottom of the pocket in the table top, and
it should highlight green, meaning it has been selected as the boundary of the
pro le to be cut out.
Heights
This tab is where the top and bottom of the cut operation are established. It
also has settings for the height the tool should move to in the Z axis to travel
safely while it's not cutting. Here are the de nitions:
Cle a ra nce He ig ht : The rst height that the tool rapids to on its way to the
start of the tool path. Must be set above material top.
Re t ra ct He ig ht : The height the tool moves up to before the start of the
next cutting pass. Must be set above material top.
To p He ig ht : The height that describes the top of the cut.
B o t t o m He ig ht : The height that describes the lowest point of the cut.
T o p He i g ht
Under To p He ig ht , click the Fro m dropdown menu and click on

S e le ct io n. Now click on any point on the top of the material to set the top
height.
B o t t o m He i g ht
Under B o t t o m He ig ht , click the Fro m dropdown menu and click on

S e le ct io n. Now click on any point on the bottom of the pocket to set the
bottom height.
You may set the Cle a ra nce He ig ht and Re t ra ct He ig ht to whatever you
please as long as they are both above the material top. Keep in mind that the
higher the Retract Height, the longer the job will take.
Passes
CNC Class: Page 40

ht t ps://player.vimeo.com/video/19064 3704 ?t it le=0&byline=0&port rait =0
This tab has all the settings for how the machine passes are generated. We
only need to concern ourselves with a couple of settings here.
To leranc e
When a CNC machine cuts a curve, its path is tessellated (made up of lots of
very small straight lines). The To le ra nce sets the length of these lines. A loose
tolerance will be faster and have a more noticeable tessellation e ect whereas
a tight tolerance will be slower and come out smoother.
I always set this to .001 because I don't mind waiting a little longer for a
smoother cut.
Ma xi mum R o ug hi n g S t e p d o w n
This is the depth the tool steps down at each pass. In general for wood and
plastics, stepdowns shouldn't be more than 1/2 the tool diameter to avoid too
much stress on the end mill, which might cause breakage. For metals, this ratio
may need to be even less than 1/2 the tool diameter.
Since my tool is 1/4" Ø, I set the M a xim um Ro ug hing St e pdo w n to .125".
Direc t ion
The direction options for CNC milling are Clim b or Co nv e nt io na l. This

describes the direction of the spindle's travel in relation to the rotation of the
end mill. Remember that the spindle rotates c lo c k wise when considering the
following options.
With Co nv e nt io na l milling, then end mill contacts the stock on the left side
of the tool. This means that the chip size e ectively starts at zero and increases
towards the end of the rotation. This generally yields the best results in terms
of nish quality and accuracy.
With Clim b milling, the end mill contacts the stock on the opposite side,
meaning the chip size starts at the maximum and tapers to zero at the end of
the rotation. This puts more strain on the tool and can decrease accuracy if the
stock de ects. This method can o er better results with softer plastics and
some metals, but in my experience it does nothing to improve wood cutting.
It bears mentioning that when you're cutting a line through the stock such
that there's material on both sides, the direction shouldn't make a di erence
since the result will be the same no matter which direction the tool travels.
With the table project, it will only make a di erence in the pocket cuts, not the
contour cuts.
CNC Class: Page 41
S t o c k t o Le a v e
I don't want to leave any stock when I make my cuts, so I unche ck t his
o pt io n .
Linking
ht t ps://player.vimeo.com/video/19064 4 388?t it le=0&byline=0&port rait =0
This tab has all the settings that tell the machine how to move from one cut to
the next and how to lead in and out of each cut.
I've had good results with all the defaults left as-is, but I like to change one:
Ra m p Ty pe . When the pocket is cut, the tool ramps down into each path
instead of plunging to a certain depth and moving laterally. This creates less
stress on the end mill.
The default Helix Ramp Type does not seem to be the best choice for the long,
skinny pro les of pockets like the one on the table, so I would advise switching
this to Pro le . The ramping is more gradual this way and seems to have
smoother results.
Simulate Tool Path
ht t ps://player.vimeo.com/video/19064 4 4 79?t it le=0&byline=0&port rait =0
When you click OK, you should get a tool path preview that looks like a series
of blue lines stepping down into the pocket. Fusion lets you simulate this tool
path so you can catch any errors before you waste material.
Fist, select one or more tool paths in the browser, then click on Act io ns >
Sim ula t e . I like to view the simulation with only the St o ck box checked. You
can navigate to the beginning of the tool path using the timeline controls and
adjust the speed.
CNC Class: Page 42

Create 2D Contour Toolpath
To cut out the pro les of the table parts, you'll make a 2D Co nt o ur toolpath.
This kind of toolpath follows a contour line and cuts at one speci ed depth.
Choose 2D > 2D Co nt o ur in the toolbar to start the process.

TOOL
The settings in this window will be identical to those in the 3D Pocket Clearing
toolpath you created previously.
Geometry
C o n t o ur S e l e c t i o n
Click on the G e o m e t ry tab and select the contours at the bottom of each of
the table parts. A red arrow will appear on each selected contour. These arrows
indicate whether the tool path will cut on the inside or outside of the line. We'll
check these to make sure they're all outside cuts after setting up our tabs.
Tabs
Tabs are bridges between the part being cut out and the leftover stock of the
plywood sheet. They keep parts in place while the end mill is making the cuts.
Without tabs, a couple cutout will result in a loose part that will be damaged
by or even thrown o the bed by the spinning end mill.
Check the Ta bs checkbox, change Ta b W idt h to .375", and leave Ta b
He ig ht at .0625". Wide, shallow tabs like this will hold the work well and will
be easy to remove after the cutting job is done.
Ta b D is t a nce is the distance between each tab on the part. The default is 2".
meaning a tab will be placed on every part with a 2" space between them. That
would be far more tabs than necessary. In general, small parts need around 2
tabs, and larger parts need more. My gut tells me that each leg should have at
least 2 tabs, and the table should have at least 6. This setting is very much up
to your discretion. The goal is to balance less work time with a more stable
cutting operation.
CNC Class: Page 43

I set the Ta b D is t a nce to 12". This gives me 2 tabs on each sti ener and
ample tabs on the other parts.
In s i d e / O ut s i d e A r r o w s
Now that you've got your tabs, you'll be able to clearly see whether each
contour cut is on the inside or outside of the line. Go to the T O P view in the
Vie w cube and zoom in on each part. Clicking the arrow on the contour line
will switch the tabs from inside to outside. Obviously, they should all be visible
on the outside of the part.
Heights
The settings here are mostly the same as the ones we covered in the Pocket
Toolpath material, but there's an additional setting to pay attention to:
Fe e d He ig ht : This is the height the tool rapids to before it changes to the
feed / plunge rate to enter the part. This isn't a concern for us because all of
our feed rates are the same. Regardless, this height must be set a bo v e the
top height of the toolpath, otherwise you'll get an error message.
T o p He i g ht
Under To p He ig ht , click the Fro m dropdown menu and click on

S e le ct io n. Now click on any point on the top of the material to set the top
height.
B o t t o m He i g ht
Under B o t t o m He ig ht , click the Fro m dropdown menu and click on

S e le ct io n. Now click on any point on the bottom of a part.
You may set the Cle a ra nce He ig ht and Re t ra ct He ig ht to whatever you
please as long as they are both above the material top. Keep in mind that the
higher the Retract Height, the longer the job will take.
Passes
To leranc e
Under the Pa s s e s tab, set To le ra nce to .0001" as before in the Pocket

Toolpath. This setting is particularly important here because these toolpaths
have lots of curves.
CNC Class: Page 44
Mul t i p l e P a s s e s
With the end mill we're using, we need to make our cut with multiple passes.
This ensures that we're not putting too much stress on the end mill, which
might cause it to break or start a re from the heat caused by too much
friction.
The rule of thumb is that each pass should step down by 1/2 the diameter of
the tool.
Linking
This tab has all the settings for how tool paths are linked together and how
the transitions are managed. The default settings should work ne for our
purposes, but keep in mind there are some very sophisticated controls here for
more complex toolpaths.
R a mp s
Ramps are an important feature to enable in this tab. They make the tool enter
the material at a gradual angle which helps reduce the lateral stress on the
end mill and prevent the stock from being nudged out of alignment.
Post Processing
D EFI NI T I O NS
Post processing takes the toolpath you've programmed in the CAM

environment and translates it to G-Code. G-Code is a type of numerical control
programming language that the CNC machine can use to cut les. It's very
simple- a bunch of commands that control the gantry and spindle. Here are
some of the commands and their de nitions:
T R: Turn router on
J3: Jog tool in 3 dimensions (not cutting)
M 3: Move tool in 3 dimensions with router on (cutting)
CNC Class: Page 45

Just about any machine can run raw G-Code, but it's best to post process your
toolpaths with code that's speci c to the machine. Depending on the CNC
machine, there may be special settings that are important for safety and best
results. Shopbot has its own G-Code based language called O pe nS BP . If
you're interested, you can take a look at Command Reference le available on
their website. If all goes well, you'll never have to look at the G-Code, but as
you get more advanced knowledge of the subject, it can be helpful to look at
the code and troubleshoot.
I NS T A L L I NG P O S T P R O C ES S I NG FI L ES
If you're running a CNC machine that needs a speci c post processor, go to the
manufacturer's website and to nd their post processing le. If you're running
a Shopbot, just use the s ho pbo t - s e p6 t h20 16 . cps le attached here and
follow these steps.
1. Download the s ho p b o t - s e p 6 t h2 0 1 6 . c p s le attached in this lesson.
2. Go to myhubs.autodesk360.com and sign in. You will automatically have an
account when you sign up for Fusion 360.
3. On the top left of the page, click the down arrow and select A 3 6 0 D r i v e .
4 . Click on the C A M P o s t s folder and add the s ho p b o t - s e p 6 t h2 0 1 6 . c p s
you downloaded here.
5. Open Fusion and click on your name in the upper right corner of the window, then
go to P r e f e r e n c e s .
6. Go to G e n e r a l > C A M and make sure En a b l e C l o ud Li b r a r i e s is checked.
P O S T P R O C ES S T O O L PAT HS
Now that your post processor is installed on the cloud and linked to in your
preferences, you can post process your toolpaths using the following steps.
1. With either your S e t up or an individual T o o l p a t h selected in the browser, go to
A C T I O NS > P o s t P r o c e s s in the toolbar.
2. Select S o ur c e > My C l o ud P o s t s and P o s t P r o c e s s > s ho p b o t -
s e p 6 t h2 0 1 6 . c p s .
3. Click OK and save the le.
I always add the diameter of the tool to the le name to avoid mistakes later.
The le will be saved with an S BP extension which can be opened natively in
the Shopbot controller software.
Download
https://www.instructables.com/ORIG/F2X/F7M4/ITW2Y62N/F2XF7M4ITW2Y62N.cps
…
Bonus!
CNC Class: Page 46

I designed and made a layout for a at-pack chair to match the table. Why not
make a CAM setup for this le and make a whole dining set? Just download
the Fusion Archive attached here and follow the same method we covered in
this lesson to make tool paths.
View in 3D Download
https://www.instructables.com/ORIG/FUR/A561/IV0ATDA5/FURA561IV0ATDA5.f3d
…
Recap
In this lesson, you learned how to create a CAM setup and export toolpaths for
CNC cutting. You learned about feeds and speeds, cut direction, pocket and
contour cuts, and how to post process G-Code.
Let us know if you've got any questions- this part takes a lot of attention and a
lot of practice!
CNC Class: Page 47

Lesson 5: CNC Router Operation
W ha t Yo u' l l Ne e d
CNC Router (I'll be demonstrating on a Shopbot)
End mills or router bits
Collet wrenches
Collets
Workholding tools and equipment
General S af et y
Long hair should be tied back and dangling jewelry should be removed before
operating any spinning machinery such as the ShopBot. Gloves should also be
removed, since they may catch on the spinning tool or spindle.
Always wear safety glasses.
Ear protection is highly recommended.
Never leave the machine running unattended, even during operations that may take
hours to run.
Take light cuts and take them slowly. Cutting too deeply or hard creates a poor
surface nish and may break your tool or wreck your material.
Keep near the EStop button in order to turn o the machine quickly.
Tools
S ho p b o t S e t up / D us t C o l l e c t i o n
CNC Class: Page 48

T o o l s a n d T o o l Ho l d i n g
W o r k Ho l d i n g
CNC Router General Info
C a r b i d e 3 D S ha p e o k o
Carbide 3D makes the "most powerful, most hackable, most complete " CNC
machine in its class. This is a simple kit which you assemble yourself in about
an hour. The machine must be plugged into a Mac or PC in order to run. All
versions come with either a 1.25 HP Dewalt spindle or a Makita spindle. Fusion
360 includes a post-processor for these machines, so it's easy to make
toolpaths and run them on the machine with good results. It's got a 3" Z
travel, which is respectable for a machine of this size.
It comes in 3 versions:
Sha pe o ko 3
Cutting area: 16"x16”

Footprint: 28-1/2”W x 24 ”L x 16”H
Weight: 70 lbs
Sha pe o ko XL

Footprint: 4 5”W x 24 ”L x 16”H
Weight: 100 lbs
Price: Starting at $14 99
Sha pe o ko XXL
CNC Class: Page 49

Footprint: 4 5”W x 4 0-1/2”L x 16”H
Weight: 14 5 lbs
In v e n t a b l e s X - C a r v e
The Inventables X-Carve is a great choice for makers with limited space and a
limited budget. It comes in 500 X 500 mm (19.5 X 19.5 in), 750 X 750 mm (29.5 X
29.5 in), and 1000 X 1000 mm (39 X 39 in) for $1,200, $1,350, and $1,460
respectively.
All models use a Dewalt router (which is easy replaceable) as the spindle and
have a 65 mm (2.5 in) Z depth which is more than enough for at pack projects
and relief sculptures.
The company claims a .075mm - .13mm accuracy resolution, which is really
impressive considering the price.
In short, if I were to own my own machine I would get the 1000 X 1000 version.
You can do a lot with 39" of width, and you can cut longer sheets if you
properly index and move the panels as demonstrated in this video.
S ho p b o t A l p ha
For this class, I'll be using the ShopBot Alpha to demonstrate the work in the
lessons. The ShopBot is a Computer Numerical Control router capable of
cutting 2D and 3D shapes in wood, foam, plastic, some non-ferrous metals,
and a variety of other materials. The ShopBot CNC machine I'm using in the
lesson is considered full-size and can handle 4’x8’ sheet goods. It is a PRSAlpha
96 48 equipped with Z-axis travel of 12” and a 24,000 RPM, 3 horsepower
Colombo spindle.
This machine can be found in marker-spaces worldwide such as Techshop.
Coordinate System
C o o r d i n a t e S ys t e m
CNC Class: Page 50

Rig ht Ha nd Rule : To be sure which axis is which, just follow the "right hand
rule". With your right hand, make an L shape with you thumb and fore nger,
then point your middle nger up. The axes are X, Y, and Z counting down from
your thumb. Remember that Z should be up.
Like other digital fabrication tools, there’s a cartesian coordinate system with
three axes - X,Y,and Z - associated with the machine. On the Shopbot, the long
axis is the X-axis, the shorter is the Y-axis, and the up and down is the Z-axis.
On the X-Carve, X is perpendicular to the controller case, making the origin on
the lower left of the table.
A CNC machine cannot be successfully operated without an understanding of
how coordinate systems are de ned in CAM and CNC machines and how the
systems work together. If you want to know more, please review Chapter 4
Coordinate Systems in the CNC Handbook at cam.autodesk.com.
We set up our coordinate system in the previous lesson to be consistent with
that of the Shopbot.
Work Holding
There are lots of di erent ways to hold stock on a CNC mill.

Va cuum t a ble s , for example,have holes or a porous sheet of LDF on the
bed and use a vacuum pump to suck the stock down to the table. These are
great for cutting large stock, but are extremely loud in my experience. Stock
must have a more or less perfectly smooth face to be sucked down to the
table, and plastic sheets must be used to cover the rest of the space in order
for proper suction to occur.
Some shops do dire ct s cre w ing with brass screws or nail into the table with
a composite nailer as mentioned above. This is fast and e ective, but the table
will get trashed very quickly and will need to be replaced and resurfaced.
T hr e a d e d In s e r t S ys t e m
The X-Carve comes with a pre-drilled spoiler board into which you drive
threaded inserts.
In o ur s ho p , the table has a similar system with over 600 gridded holes, with
threaded metal inserts. Nylon shoulder bolts are screwed into the inserts to
hold materials, and wooden hold-down blocks with slots milled into them
make it easy to hold stock of any size.
9/16" Ø holes are drilled by the Shopbot on a 4" X 4" grid, and 1/4"-20 thread
size threaded inserts are screwed into the holes. 1/4"-20 nylon bolts are used
to screw into the threaded inserts in conjunction with slotted blocks.
CNC Class: Page 51

Us i n g t he Ho l d D o w n s
On one side, bolt down a re g is t ra t io n blo ck to ensure the stock is properly

aligned with the Shopbot Axes. Then use hold downs on the other three sides
to keep your material from pulling up.
1. Put your material down on the Shopbot table. On one side, choose two holes near
the material that are a few inches apart. Blow debris out with compressed air.
2. Place a hold down block at on the table, with the long edge ush against your
material. Then screw the hold down block to the table with two nylon bolts,
starting by hand and tightening with a wrench. Be careful not to overtighten more
than ¼ turn so you don’t destroy the threads.
3. Gather a few scrap blocks of your material or another material that is the same
thickness. You can also use extra hold downs if your material is 0.5” thick. You will
use these blocks to balance the back end of your hold downs when they’re placed
over your material, ensuring that they’re applying force evenly.
4 . Choose where to place your hold downs—at least one on each of three sides and
spaced at 3’ intervals—and then blow debris out of holes between your material
and the scrap blocks. Screw a nylon bolt through each hold down and tighten with
a wrench.
R ul e s o f T humb
Avoid cutting into the table. Skimming o 1/32" to ensure a full depth cut is
generally ne.
Do not screw or nail into the table. There is no need given our work holding system.
Before securing your material to the table, use calipers to measure its thickness.
this will be important when setting the work home Z height.
Ho l d i n g Ful l S he e t s
Full sheets (4' X 8') cannot be used with the threaded insert system because
they cover the entire bed. For full sheets, use clamps around the edges to hold
down the stock.
We use adjustable spring clamps in our shop because they only cover about
3/4" of the stock around the edge of the table. Trigger clamps also work well,
but they cover more of the stock around the edges, leaving less usable space
on the sheet. Here's how it works:
1. Square the panel to the ShopBot table.
2. Use clamps to hold each corner and side of the panel. Use a minimum of 8 clamps -
one at each corner and one on each long edge.
3. For sheets that are cupped or bowed, place the belly of the sheet down so the
edges lift up from the table.
CNC Class: Page 52

Tool Interface and Software
From this point on, I'll be using the Shopbot Alpha to demonstrate CNC
operation.
S a f e t y Fi r s t
CNC routers may do unexpected things! There are two ways to stop the
Shopbot quickly.
S PACEBAR: Pressing the spacebar will pause the gantry and apply the brake
to the spindle. The spacebar will not cause the machine to lose its location, and
the machine can be easily restarted. This is the preferred way to stop the
machine.
EM ERGENC Y S T O P: There are two Emergency Stop (E-stop) buttons on the
machine. Using the E-stop will stop gantry movement. The spindle will lose
power, but the brake will not be applied, so it will keep spinning for a few
minutes. The machine will also lose its known position, so you will need to reset
home and restart your job.
The Shopbot is controlled by a PC that is permanently plugged into the
machine as it runs a toolpath. The Shopbot control software can run toolpaths,
move the gantry manually, home the axes, run surfacing operations, and
simulate tool paths among other things.
Ma c hi n e S t a r t up
CNC Class: Page 53

1. Turn on the computer.
The computer will be plugged into the shopbot via an ethernet cable if
it was setup using standard Shopbot instructions.
2. Turn on the ShopBot.

On the side of the machine, rotate the red switch clockwise to the ON
position.
3. Open the ShopBot 3 Software.

Launch ShopBot: the software that controls the machine.
A popup window (STOP Button is ON!) will appear, even if no E-stop is
pressed.
Check and reset both E-stop buttons by turning them clockwise.
Click OK.
C o mma n d C o n s o l e a n d P o s i t i o n
There are two windows that control the ShopBot: Co m m a nd Co ns o le and

the Po s it io n dialog box.
Co m m a nd Co ns o le :
The window in the center, the Command Console, has standard drop down
menus that contain commands. You can also enter individual commands to
move the tool or run a part le. When the part le is running, this winow will
scroll through the G-code./
Po s it io n D ia lo g B ox:
The red Position dialog box on the right side of the machine displays X, Y, & Z
coordinates and icons that set up and run the machine.
T ip: Hover your mouse over the icons for descriptions.
S e t t i n g Ma c hi n e X , Y Ho me
In order to cut a part, you have to set the starting point of the tool path. When
the Shopbot is turned on again, the computer will assume that the gantry is in
the same position it was in before it was switched o . That means if the gantry
was moved by hand (to remove stock, for example) while the machine was o ,
the X and Y home will be way o .
To avoid errors, always ho m e the machine at the beginning of a job. Our
machine has proximity (prox) switches, so it can be homed automatically
through the Command console. Once the global home is set, you've got a
reference for establishing for setting your tool path home.
CNC Class: Page 54

1. Reset the stepper motors
Press the blue Reset button on the pendant.
Do not move the gantry by hand when the control box is ON.
1. Machine Home X, Y
Ensure the bed and rails are clear—the Shopbot is about to move
Click Cuts in the top menu and then choose Home X Y Axes Using Prox
Switches (keyboard shortcut C3)
After Shopbot moves to home location, you'll get a warning dialog
box. Click OK to proceed.
No P r o x S w i t c he s ?
If your machine doesn't have prox switches, there's an easy way to set the X
and Y home. With the power o , move the spindle to the hard stops on the X
and Y rails, then turn the machine o n and set the X and Y home manually.
Tool Changing
>
With the machine homed, it will already be in a good position to change or

insert an end mill. This part is easy but there are a few important things to
consider.
D us t S hr o ud
We have a dust shroud installed on our Shopbot. To access the spindle, use the
Allen key on the bolt near the top of the spindle to lower the dust collector
shroud so you can access the spindle.
T o o l In s e r t i o n
It's very important to ensure that the end mill is inserted into the collet at the
pro pe r de pt h . The utes must be completely exposed to avoid clogging, but
the shaft must have the maximum possible length inserted into the collet to
avoid dislodging.
CNC Class: Page 55

To insert a tool, rst insert the collet into the collet nut, then screw it onto the
spindle end a couple of turns. Don't go too tight or it will be to hard to get an
end mill inserted.
Next, insert the end mill to the proper depth, then tighten the nut against the
spindle. Do n' t g o t o o t ig ht ! If the collet it too tight you risk damaging the
spindle threads and making it very di cult to remove the nut later.
A good rule of thumb is to position the wrenches so that they're next to each
other, then tighten using one hand. This will ensure the proper tightness on
the threads.
CNC Class: Page 56

Job Homing and Z-Zero
Now that the tool is inserted, it's time to set up the tool path home and Z axis
zero height. The image above shows an example of where the stock may be
located in relation to the machine home and table corner.
1. M A C HI NE HO M E: This is the absolute limit of the gantry on the X and Y axes. We
established this previously using either proximity switches or hard stops.
2. S P O I L ER B O A R D (T A B L E) C O R NER : On our Shopbot, the table is o set
from the machine home by less than 2 inches in each dimension. On some
machines, the table is perfectly aligned with the machine home.
3. S T O C K O R I G I N: The stock to be cut can be any size that will t within the table
boundary (4 8 " X 96" in our case). Depending on the placement, the origin point of
the stock must be set manually. In the case of a 4 'X8' sheet, the table corner and
stock origin should be the same.
4 . S A FE C U T T I NG A R EA : This must be considered when laying out the parts to
be cut before tool paths are made. A 1" wide margin around the edges is usually
enough to allow for the tool to cut without crashing into work holding.
CNC Class: Page 57

Ho me X + Y (S e t S t o c k O r i g i n )
To set the stock origin, move the spindle up in the Z axis to avoid crashing,
then use the keypad to move the spindle in the X and Y dimensions in order to
align the end mill tip with the origin point of the stock already xed to the
table.
M a ke a no t e of the X and Y position in the keypad. These numbers tell you

where the spindle is in relation to the machine home. If something goes wrong
with your job and you have to shut down the machine in the middle of a job,
you'll be able to re-home the machine, then manually enter the values you
recorded for X and Y location. This will allow you to continue the job without
wasting the stock that was partially cut.
You won't be able to line it up exactly with the corner by eye-balling an end
mill, but it will be close enough for a at-pack project with a 1"+ margin
around the edges of the stock.
Click on Z e ro Axe s and check X-Axis and Y-Axis in the list, and the keypad
will now read X=0 and Y=0.
Air Pas s
To ensure that you’ve placed your Work Coordinate System correctly and to
verify your program, conduct an air pass before actually cutting your part.
With the Z set well above the top of the stock, you'll be able to follow the
toolpath to ensure that it's oriented properly and doesn't have any
catastrophic errors.
S E T AIR PAS S Z - Z ERO
1. Raise the spindle to a level about 4 -5 inches above your stock, so it won’t collide
with the stock during the air pass.
2. Click Zero Axes in the Keypad dialogue.
3. Make sure that Z i s c he c k e d .
4 . X a n d Y mus t n o t b e c he c k e d .
5. The dialogue box will con rm that Z has been set to 0.
6. Close yellow control pad.
LO AD PART FILE
CNC Class: Page 58

1. Insert the key that’s attached to the spindle wrench into the machine, and turn it to
enable the spindle.
2. Click Cut Part in the Position Dialogue.
3. Find and load your .sbp le.
4 . Click Start in the Position Dialogue.
5. The machine will run through a few lines of code, and then a dialogue box will come
up reminding you to start the spindle. The spindle does not automatically start: -Do
NOT press OK yet.
6. Press the R e s e t b ut t o n on the pendant and press the S t a r t b ut t o n on the
pendant to start the spindle
7. Turn on the dust collector if you have one.
8. Click OK in the dialogue box to start cutting.
Watch the machine for about 1 pass to make sure the X and Y movements are
what you expect. Even with a lot of experience, it's a common mistake to switch
the X and Y axes in the tool path. An air pass is the best way to ensure you
didn't make a mistake like this.
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Z e r o Z A xi s
Setting the top of your workpiece to Z Zero and entering the exact thickness in
the CAM software will prevent cutting the table with your end mill. Use
calipers to measure your exact material thickness, and ensure your stock in
your CAM le is updated.
Z ERO ING W IT H A Z ERO PL AT E
Some CNC routers are equipped with a zero plate. This is conductive metal
plate with a thickness that's programmed into the machine's computer. You
can run a command that will move the tool down until it touches the plate,
then the software will automatically subtract the plate thickness and give you
an exact Z height.
1. Jog the spindle over your workpiece.
2. Set the zero plate directly under the end mill.
3. Attach the ground clamp to the stando on the spindle.
4 . Close yellow control pad.
5. Click Cuts in the top menu and then choose Zero Z Axis with Zero Plate. (keyboard
shortcut C2)
6. Press enter when ready to zero.
7. When done with the z plate remove the ground clamp and zero plate.
Z ERO ING M ANUALLY
CNC Class: Page 59

I you don't have a zero plate, you'll have to zero manually. To do this, just put a
piece of paper down on the top of the stock, then nudge the spindle down
until it touches it. You should be able to move the paper but feel a little
resistance on it. This should give you a zero that's close enough to perfect that
your toolpath will give you the results you want.
Run Toolpath
Now that your machine is zeroed in all 3 axes and you've done an air pass, it's
safe to run your toolpath and cut out the parts.
Lo a d P a r t Fi l e
Go back to the LO AD PART FILE instructions above and repeat those steps.
Remember to pay attention and keep the E-Stop at the ready incase
something goes wrong.
P o s s i b l e P r o b l e ms
Always stay close to the machine with the E-Stop button at the ready. Here are
some common problems that can occur while a part is running.
1. G - C o d e Er r o r : It's rare, but sometimes the code will have an error. In some
cases, this can cause the tool to dive into the bed when it travels from one pro le
to the next instead of going up like it's supposed to. You'll know this error when
you see it (or rather hear it). This isn't usually dangerous, but it can cut a nasty
gouge in your table.
S o l ut i o n : Go back to the Fusion CAM environment and check the
tool path preview again. You may have missed the fact the one of the
yellow traverse lines went through the material. Usually in this case it's
best to just redo the toopath.
2. D i s l o d g e d t o o l : If the collet wasn't tight enough, the end mill is likely to shift
down in the collet. This can gouge your table and even send the end mill ying, with
is dangerous.
S o l ut i o n : Reset the end mill in the collet with the proper depth, then
tighten the nut a bit tighter this time. You'll have to re-zero the Z axis.
Assembly
CNC Class: Page 60

Finished Product
If you made a CAM setup for the chair le, you can make a whole dining set!
If you stayed with us the whole way through, you've learned enough about
CNC to get going on your own projects. Remember that this kind of work takes
lots of practice and you'll probably make a lot of mistakes the rst several
times you make projects.
Stick with it, keep practicing, and pay close attention at every step. Keep
experimenting, and you'll get more comfortable every time you use the
machine.
CNC Class: Page 61

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instructables classes

CNC Class: Page 1

Lesson 1: Tools and Materials for CNC

Lesson 2: Flat Pack Furniture

Lesson 3: Flat Pack Design Preparation

Lesson 4: CNC Router CAM Setup

Lesson 5: CNC Router Operation

CNC Class: Page 2

ht t ps://player.vimeo.com/video/188201991?t it le=0&byline=0&port rait =0

CNC Class: Page 3

Ungloo, Joshua Tree, CA, 2008

To learn the subject, we'll focus on at-pack design by making a full-sized

Flat-Pack Dining Table

Flat-Pack Dining Chair

CNC Class: Page 4

CNC Design & Fabrication Process

CNC Class: Page 5

CAM (Computer Aided Manufacturing) involves taking one or more 3D objects

CNC Class: Page 6

Cutting area: 16"x16”

Cutting area: 16x33”

CNC Class: Page 7

Cutting area: 33x33”

CNC Class: Page 8

Amazon: 1/8" Ball Nose End Mill

CNC Class: Page 9

Wood and Plywood

My advice is to locally source your wood- it tends to be cheaper than ordering

CNC Class: Page 10

CNC Class: Page 11

This lesson will demonstrate a step-by-step method of designing a at-pack /

You're going to design a table that's at-packed and friction- t. Fla t - pa ck

The Fusion Interface

CNC Class: Page 12

1. A p p l i c a t i o n b a r : Access the Data Panel, le operations, save, undo and redo.

CNC Class: Page 13

ht t ps://player.vimeo.com/video/188208088?t it le=0&byline=0&port rait =0

A component is an encapsulated part that can have one or more 3D bodies or

Go to S KE T CH > Cre a t e Ske t ch , and click on the bottom plane of the

CNC Class: Page 14

ht t ps://player.vimeo.com/video/188208215?t it le=0&byline=0&port rait =0

To set a parameter, go to M O DIFY > Cha ng e Pa ra m e t e rs , click the g re e n

CNC Class: Page 15

You can go back to M O DIFY > Cha ng e Pa ra m e t e rs and change the

Move Table Top Component

ht t ps://player.vimeo.com/video/188209352?t it le=0&byline=0&port rait =0

Sketch Leg Profile

ht t ps://player.vimeo.com/video/188209521?t it le=0&byline=0&port rait =0

CNC Class: Page 16

CNC Class: Page 17

CNC Class: Page 18

Create First Leg

ht t ps://player.vimeo.com/video/188209711?t it le=0&byline=0&port rait =0

To do this, set D ire ct io n t o Sy m m e t ric, and D is t a nce t o t /2. This will

Create Tab Feature

ht t ps://player.vimeo.com/video/188210778?t it le=0&byline=0&port rait =0

CNC Class: Page 19

To create a tab, go to S KE T CH > Cre a t e and select the f ro nt f a ce o f t he