Understanding the Basics

of Hand Taps and Carbide

Taps
July 2017
基礎から分かるシリーズ
ハンドタップ・超硬タップ編
 Understanding the Basics of
Hand Taps and Carbide Taps

・What is a Hand taps ?

・Hand taps and Serial hand taps

・Cutting torque of taps

・What is a carbide tap ?

・The relationship between an internal

thread, a tap and a gauge.

・Yamawa’s offering of Hand taps.

・Yamawa’s offering of carbide taps.

・Taps for cast irons.

・Carbide Taps for high hardness steels

・Selecting hand taps/carbide taps based

on workpiece materials being cut.

・Introduction of RE-HT

・Introduction of UH-CT/EH-CT

2
 What is a Hand taps？

A hand tap is used for general tapping work. The same diameter is offered in three
types of cutting chamfer lengths for manual tapping. The first is a taper chamfer, the
second is a plug chamfer and the last is a bottoming chamfer. These are sold as a set
for general tapping. In succession, these are used with the starter taper chamfer tap
cutting first, depending on the work piece condition. Yamawa currently produces the
plug and bottoming chamfer taps.
<Fine chips are created with
hand taps>
Plug type：
5 thread chamfer

Bottoming type :
1.5 threads chamfer

※The serial hand tap is explained on next page.

<The classification of a tap’s cutting action is based on the geometry of the taps, the chip direction and
the hole shape>

Hand Taps

Spiral Fluted Taps

Spiral Pointed Taps

The characteristic of hand taps are summarized as below.

1) High cutting edge strength.
2) Suitable for tool wear prone materials like high hardness materials and cast irons.
3) The cutting chamfer length can be selected.

3
Hand taps and Serial hand taps

●Hand taps（used in many other countries besides Japan)

Hand taps have two or more taps with the same thread diameter and a different num-
ber of threads in the cutting chamfer section. There are three lengths of cutting cham-
fers offered in the same diameter tap.
Yamawa sells plug and bottoming taps as standard products.

●Serial taps（mainly used in Europe market）

Serial hand taps are made to have two or more taps that remove an increasing
amount of thread material. These taps are offered as one set. After the first ”V” starter
tap is used, each additional middle “M” and “Finishing “F” tap of the same diameter
removes more of the read diameter. First the tapping is done with “V” with the lowest
thread form, then “M” →”F” is processed.

【Yamawa product catalog on “Products for Europe” page】

【Product catalog 2015-2016 HT page】

4
Cutting torque of taps

The charts below show torque diagram comparisons of hand taps, spiral fluted taps
and spiral pointed taps with their torque values.

☆Selecting the same processing conditions and in the same material and hardness
while using the same diameter and pitch tap with the same chamfer the tapping
torque for each style is shown above.
The tapping torque can change depending on the type of cutting fluid and chip
effect.
☆Spiral pointed taps are less affected by chips when compared with other taps.
The tapping torque appears low in the charts above.
☆Spiral fluted taps discharge the chip back toward the shank inside the flutes.
The taping torque for spiral fluted taps will become slightly larger compared that
tapping torque of a spiral pointed taps.
☆While using hand taps, the chips accumulate in the flutes, so the tapping torque
increases due to the influence of the chip storage.

5
What is a carbide tap？
In recent years, taps are being used on machines that are dedicated, like automated
machines, CNC machines, machining centers, etc. Yamawa has promptly responded
to these times and recommends a carbide tap that is popular for mass production and
that offers greater cost reduction. If applied properly, it is more than 50 times more du-
rable than the general HSS tap.
■Features:
1）Yamawa uses ultrafine particle cemented carbide that has a high resistance to breakage
and it exhibits high toughness. The Yamawa carbide taps have the same hardness as that of
conventional cemented carbide.
2）Because it is hard and has high toughness it offers better abrasion resistance and longer life.
3）Depending on the application, it is also possible to thread difficult to cut materials.
■Usage notes:
1）Machines used: Carbide taps develop chipped cutting edges if the vibration is large.
Carbide taps have a low bending strength and can break if too much side stress is generated.
2）Mounting and holding tool: Misalignment prevention to the minor diameter hole is vital.
Mounting tap in accurate holders is critical. (Carbide taps are easy to break due to bending
stress. )When attaching the tap to the holding tool is inaccurate, the holding tool will float or
move, throwing the balance of the tapping operation off and it can easily develop into chip-
ping and breaking.
3)Threading holes: Threading where the hole is bending or misalignment will cause a bending
stress and breakage. Pay attention to the depth of the hole and the length of the screw
thread. Pay particular attention to chip clogging and crash into the bottom.
4）Lubrication: Use mainly tapping lubrication. (It helps prevent the development of chip
welding to flute. Higher tapping torque can develop from the chip welding and cause break-
age.
5）Wok material: The toughness of a carbide tap is lower than that of a HSS material so the
range of the work material is limited.
≪About work material≫ Cemented carbide does not have the
toughness of HSS taps, so cutting edge chipping and tap breaking
can easily occur. It is best to limit the work material to those where
the metal chips are divided finely as shown in the picture on
the right. Typical examples of these materials are cast iron and
aluminum die casting. Recently, carbide taps have also been used
for ultra high hardness materials exceeding 60HRC.

≪About the main tap types≫

・For cast irons・・・N-CT FC
・For light alloys・・・N-CT LA
・For high hard materials (hardness: 45HRC～55HRC）・・・EH-CT
・For ultra hard materials (hardness: 55HRC～63HRC）・・・UH-CT
・For ultra fast tapping speed・・・HFACT HFICT

6
 The relationship between an internal thread , a tap and a gauge.
Hand taps have larger thread class because they tend to cut closer to tap size.
We recommend using oversized taps for the following conditions.

1). When the material has a tendency to shrink after tapping due to the shape of the work piece.
2). If a plating is applied to the internal screw thread after tapping. (The tap diameter needs to
be approximately four times of the plating thickness.)
3). When the work piece material does not expand but the tap experiences rapid wear.
4). When tapping on machines with a rigid tapping mechanism. If there is no expansion in the
axial direction of the holder, we suggested the use of a tap with a class as high as possible.
5). Choose a tap that has as large of a thread class as possible.

Comparison graph of tolerance zone for Pitch Diameter of

a internal thread, a gage and tap thread class for M10X1.5
Pitch
diameter Pitch
Position of
tolerance Position diameter Position of
Position of Yamawa
zone of of Plug tolerance Yamawa
Size: M10X1.5 JIS 2nd gauge zone 6H
Plug gauge P class
G class
class 2 Cutting
class JIS 2nd internal Roll Taps.
Taps.
internal thread
(μmm) thread
200

190
Maximum figure of pitch NP
diameter of 6H internal 180
thread for M10X1.5 :
9.206mm 170

160

150
Standard thread classes of each tap for
IP
Maximum figure of pitch 140 M10X1.5 and the figure of pitch diame-
diameter of JIS 2nd class
internal thread for 130 ter.
M10X1.5 : 9.166mm (Roll tap: Recommended tap thread
120
class)
110 ・SP P2 M10X1.5 P2=+20~+40μm
100
・PO P3 M10X1.5 P3=+40~+60μm
6H G8 ・HT P3 M10X1.5 P3=+40~+60μm
90 internal
thread ・N-RZ G7 M10X1.5 G7=+76~+89μm
80 JIS 2nd G7
class
70 P4
internal
60 thread

50
P3
(PO, HT)
40

30
P2
（SP)
20

10 GP
Basic Pitch GP
Diameter: 9.026mm 0

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 Yamawa’s offering of Hand taps

Product
Product Features Size range
Symbol

The IHT taps are for drilling machines or for hand

tapping. It is suitable for small volume tapping on
IHT work piece materials like SPC and SS400. M3～M10
We recommend tapping speeds less than
I series Hand taps for General 5m/min.
Purpose Application

The HT are widely used for general-purpose tap-

M1～M48
HT ping applications. We recommend tapping
U、W、SM
speeds of 5 to 10m/min.
Hand Taps

HT LH The HT LH hand taps are for left hand threads. M1～M30

Hand Taps for Left Hand Threads

The LS-HT taps have a longer shank than conven-

tional taps. These taps are applicable for use
LS-HT M2～M30
where the tapping length can not be reached
with a standard length tap.
Long Shank Hand Taps
The LS-HT V is a thin film coated longer shank that
is longer than a conventional tap. These taps
coating improves wear resistance and welding
LS-HT V M3～M12
resistance.
Long Shank Hand Taps, Coated The LS-HT V are for use where the tapping length
can not be reached by a standard length tap.

The SU-HT is the hand tap suitable for sticky work

M2～M30
SU-HT hardening stainless steels, chrome steel and mo-
U、W
lybdenum steels.
Hand Taps for Stainless Steels

The FC-HT taps are suitable for hard and brittle

FC-HT materials like cast iron. The FC-HT is slightly over- M3～M24
size to allow for faster wear in hard materials.
Hand Taps for Cast Irons

The LA-HT is an oversized tap that corresponds to

materials that end to contract when tapping in-
LA-HT M1.4～M24
ternal threads like aluminum alloy die castings
(ADC) and zinc die castings (ZDC).
Hand Taps for die casting

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Product
Product Features Size range
Symbol
●The AXE-HT is ideal for machining aluminum alloy
castings and zinc alloy castings.
●Powder HSS (characterized by high wear re-
sistance and heat resistance) with a special coating.
●When combined with the correct tooling, the tool
life of the AXE-HT is increased five times over conven-
AXE-HT tional taps designed for aluminum. M6～M12
AXE Straight Fluted Taps ●With less flute damage, the dimensional change of
the internal threads is improved plus there is an im-
provement in the surface finish.
●Suitable from medium speed to high speed with
an optimum combination of negative rake angle
and eccentric relief.

The EH-HT is a hand tap suitable for tapping of

high hardness steel range from 35 to 45HRC. It
EH-HT M3～M30
works best in high carbon steels, alloy steel
Hand Taps for Hard-to-Machine forging, tempering material, mold material, etc.
Materials

The PL1 is a tap for a thermosetting resin.

PL-1 This material can be difficult to create a screw M2～M8
thread in, especially the synthetic resin.
Hand Taps for Plastics

The number of the cutting chamfer threads is

set to 1 thread or less. The MG-HT is optimum
MG-HT M1.4～M3
when the requirement is a full thread at the
Hand Taps with Short Chamfer for bottom of a hole.
Magnesium Alloy Castings

The MC-HT is a coolant through tap with side

ports for through hole tapping applications.
MC-HT M6～M30
The internal coolant supply improves the sur-
Hand Taps with Internal Coolant face finish and tool life.
hole

New
Main usage of RE-HT is for correcting thread
RE-HT flaws, and cleaning out burrs, paint, rust and M50~M80
Joint type taps for thread repair residual spatters from welding.
and cleaning

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 Yamawa’s offering of carbide taps
Product
Product name Features Size range
symbol

The N-CT LA is suitable for mass production of alu-

minum castings (AC), aluminum die casting
N-CT LA (ADC), zinc die casting (ZDC) and other mass pro-
M1.4～M20
Carbide hand taps for light alloy duction products.

The N-CT FC is suitable for screw thread tap-

M1.4～M24
N-CT FC ping of mass-produced products that are
No.4～3/4
Carbide hand taps for cast iron hard and brittle material like cast iron.

The N-CT PO is carbide tap for a through

hole tapping of screw threads in mass pro-
N-CT PO M3～M12
duction in hard and brittle materials such as
Spiral Pointed Carbide Taps
cast iron.

●Ideal for high hardness steel tapping from

45 to 55HRC in steels for hot dies like SKS3,
SKD11)
●The EH-CT is an ultrafine particle cemented
EH-CT carbide superior in abrasion resistance and M3～M12
impact resistance.
Carbide hand tap for high hard- ●Recommended for bored hole of 6H
ness steel
internal thread diameters should be the
maximum value.

●The UH-CT is for SKD materials pre-

hardened steels 55 to 60 HRC (Max63HRC).
●Ultrafine particle cemented carbide
superior in abrasion resistance and impact
Carbide hand tap for Ultra Hard resistance.
UH-CT Materials ●Screw thread length is set to 1.5D or less. M2～M20
Taking life into consideration, the cutting
chamfer is 5 threads long.
●For the diameter of the bored hole 6H in-
ternal thread diameters should be the maxi-
mum value recommended.

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 Product
Product name Features Size range
symbol

The HFACT-P is a carbide tap capable of ultra

high speed tapping.
The tap has an internal hole with side ports for
HFACT-P M6～M12
lubrication or mist in through hole tapping.
Carbide Taps for Ultra Fast It is suitable for tapping aluminum casting or
Tapping, Through Hole Use, aluminum die casting.
for Aluminum

The HFACT-B is a carbide tap for super high

speed tapping. The tap has a straight internal
HFACT-B Carbide Taps for Ultra Fast Tap- coolant hole for lubrication or mist in blind M6～M12
ping, Blind Hole Use, for Aluminum hole tapping of aluminum casting and alumi-
num die casting.

The HFICT-P is a carbide tap capable for ultra

high speed tapping. The tap has an internal
HFICT-P Carbide Taps for Ultra Fast Tap- M6～M12
coolant hole with side ports for lubrication or
ping, Through Hole Use, mist in through hole tapping in cast irons.
for Cast Irons

The HFICT-B is a carbide tap for super high

speed tapping. The tap has a straight internal
HFICT-B M6～M12
coolant hole for lubrication or mist in blind
Carbide Taps for Ultra Fast Tap- hole tapping of cast irons.
ping, Blind Hole Use, for Cast Irons
Direct cored hole tapping result in a reduc-
tion of processing time.
The shank diameter is the same as the thread
diameter of the tap which improves rigidity
M6,
Spiral Fluted taps for tapping and makes the product more resistant to de-
M8,
ACHSP Cored Holes in Aluminum flection and the cutting side pressure caused
M10X1.5
from misalignment. (M6, M8: 0.3mm max,
M10X1.25
M10: 0.6mm max)
A thin film coating offers improvements in
wear resistance and a reduction of cutting
edge chipping.

11
Taps for cast irons
Cast irons is a widely used material for mechanical parts. It contains up to 6.7% carbon (C)
and has a hardness around 230-270HB. Since cast irons are abrasive Because the chips are
very fine, there are few flute chipping problems from the metal chips wrapping around the tap.
Cast irons is relatively easy to process. Yamawa recommends the FC-HT hand tap for cast irons.

<Features of FC-HT>
①Recommend cutting speed:Less than 10m/min.
②Machine: A wide array of machines can be used to tap cast iron from CNC
machining centers to drill machines.
③Material: The FC-HT tool material is high speed tool steel (HSS).
④Surface treatment: When a nitride surface treatment is applied the surface hardness
of the tap becomes 1,000 to 1,300HV and the wear resistance very high.
⑤Rake angle: The cutting edge shape has a rake angle with high rigidity.
⑥The problem of a thread gauge measuring tight is compensated for by making the
FC-HT slightly oversize.

The following table compares the number of the holes tapped until the thread gauge
measured tight from performing tapping tests on FC250 material with a standard HT
and a FC-HT. It was possible to tap about 2,700 holes with the FC-HT compared to 720
with a standard HT. The FC-HT achieved more than three times the number of holes
tapped with a standard HT.

<Comparison test of HT and FC-HT M8X1.25>

Product HT, FC-HT P3 M8X1.25 5P

Work piece material FC250
Tapping length, Hole shape 12mm (for through hole)
Bored hole size φ6.8
Machine Machining center (Fully synchronous)
Tapping speed 12m/min
Lubrication Water soluble (*20 Dilution ratio)

HT

FC-
HT

0 500 1000 1500 2000 2500 3000

Number of tapped holes

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 Next, the introduction of the N-CT FC carbide taps for cast irons.

The N-CT FC is a tap made from an ultrafine carbide(HF) with a cutting angle specifica-
tion based on the FC-HT tap to greatly increase wear resistance. The figures below
show the comparison of the number of tapped holes and the wear width on the
chamfer. The chart below shows a comparison of tap tool life using the N-CT FC to that
of the same size HT M8X1.25 tap. The HT tool life was about 2,000 holes and the abra-
sion of the chamfer was large. It became difficult to continue tapping while holding
size. The N-CT FC had a tool life of 20 times more with less abrasion on the chamfer
even after tapping 50,000 holes.

Comparison <Test condition>

<Abrasion of chamfer portion>

graph of abra- N-CT FC P4 M8X1.25 3P

sion amount at Product, Size
chamfer por- HT P4 M8X1.25 3P
tion between Workpiece material FC250
N-CT FC and
HT tap. Hole shape 12mm (for through hole)
Bored hole size φ6.8
Machine Machining center (Fully synchronous)
Tapping speed 12m/min
<Number of tapped hole (pcs/hole) Lubrication Water soluble (*20 Dilution ratio)
To use the N-CT FC taps properly without having problems, it is important to improve
the processing environment. The hardness of the N-CT FC is much harder than HSS.
Carbide toughness is lower than HSS, so flute chipping and breakage problems are
likely to occur if not applied properly. When using the N-CT FC, be careful of any
deviation of processing axis, curvature of pilot hole and positional deviation.

Tapping effectiveness in FC-HT and N-CT FC

Product Tapping condition
Tapping Tapping Number of
Chamfer Workpiece Hole Feed
Tap Size length speed Machine Lubrication tapped hole
length material shape mechanizm
(mm) (m/min) (hole/pc)
M5X0.8 1.5P FC250 Blind 12 15 MC Synchronized Water soluble 2,100
Special-purpose
M8X1.25 1.5P FC250 Blind 18 8 Asynchronized Water soluble 2,400
machine
Special-purpose
M10X1.5 1.5P FC250 Blind 20 8.5 Asynchronized Non water soluble 2,500
FC-HT machine
M10X1.5 1.5P FC250 Blind 12 7.5 Tapping machine Master screw Non water soluble 3,000
M10X1 1.5P FC250 Blind 14 10 MC Synchronized Non water soluble 5,000
Special-purpose
M12X1.75 1.5P FC250 Through 30 9.4 Asynchronized Non water soluble 4,300
machine
M6X1 3P FC250 Through 15 7 Transfer machine Asynchronized Mist 30,000
M6X1 3P FC250 Through 12 12 MC Synchronized Water soluble 70,000
M7X1 1.5P FC250 Blind 8 15 MC Synchronized Water soluble 50,000
N-CT FC M8X1.25 1.5P FC300 Blind 24 10 MC Synchronized Water soluble 64,000
M10X1.25 3P FC250 Through 15 15 Tapping machine Asynchronized Dry 16,000
Special-purpose
M10X1 1.5P FC250 Blind 8 8 Asynchronized Water soluble 40,000
machine

13
Carbide taps for high hardness steels
There are many types of mold available in the industry depending
on the application. Typically, these are divided into two categories,
molds (Mold) used for casting and resin molding and a press die
(Die Molds) used for press working of metal. For the die mold, a pre-
cipitation hardening system is applied which heat treats
(tempering ) to hardness of about 40HRC. Steels used for plastic or
resin material molds are stainless steels with excellent corrosion re-
sistance. For press dies, it is important to have wear resistance, so
there is a common use of alloy tool steels (SKD11, SKS93, etc.) that have been heat treated to
harder than 50HRC. The general use of taps made from high speed tool steel (HSS) means the
hardness of the tap is about 64HRC and it is difficult to process a mold material with hardness
exceeding 45HRC. Therefore, YAMAWA has create a lineup of cemented carbide taps “EH-CT”
for high hardness steel and a carbide taps “UH-CT” for ultrahigh hardness steel for tapping high
hardness steel 45HRC or more.
EH-CT:Suitable for high hardness tapping 45～55HRC such as steels for hot mold(SKS3, SKD11, etc)
UH-CT: SKD material, pre-hardened steel etc. Ideal for tapping 55-60HRC.

【Precautions on Processing】
①Make the hole diameter as large as possible within an allowable range and work. If the bored hole
is made larger, the processing load is reduced, so more stable tapping becomes
possible. Hole dia.
②Make the depth of the prepared hole as deep as possible within an allowable
range. If the tap cuts the chips that accumulated a the bottom of the bored holes,
this will create a flute chipping problem. ※Since the length with chamfer is “5
threads”, set the depth of bored hole and take into consideration the length with
Hole depth

Threading length

chamfer. ・If it is not possible to deepen the bored hole, we suggest that once you
have tapped about half of the thread length, remove the tap once, remove the
chip continue tapping to the bottom of the hole.
③Pay attention to vibration while tapping, tap bending, the cutting speed and pro-
cess it.

14
 Selecting hand taps/carbide taps based on work piece materials being cut.
Red colored taps: Taps for fully synchronized feed
Yellow colored taps: Carbide taps
Recom- Recom-
mendation Surface mended
Material Features of material Purpose/Spec.
by YAMA- treatment speed
WA (m/min)

These materials have a high ma-

Low
chinability rating but can often ma- For drilling/
Carbon IHT OX ～5
terial welding on the tap when cut- by hand
steels
ting internal thread.
General
HT - 5～10
purpose
For left hand
HT LH - 5～10
These steels are widely used in all threads
Middle industries and have a high machin-
carbon ability rating. LS-HT Long shank - 5～10
steels This material is easily tapped with a Long shank tap
general purpose tap. LS-HT LH for left hand - 5～10
threads

Tap with coolant

MC-HT hole
- 5～10

These materials can become harder

as the carbon content increased.
High This increased hardness results in
carbon rapid tap wear. LS-HT V Coating Coating 10～20
steels If you have heat-treated thermal
refined materials, then select a tap
designed for thermal refined steels.
This is a material whose hardness has
Thermal Hard-to-
increased through heat treating
refined EH-HT Machine - ～5
and tapping has becomes more material
Steels
difficult.
Steels that are heat-treated to a Hard material
hardness over 40HRC may not EH-CT (45～55HRC)
Coating ～5
thread well with a general purpose
Heat tap and you may have difficulties
treated with tool life or tap breakage.
Ultra hard
steels In the case of volume tapping of
UH-CT material Coating ～5
this type of material, special pur- (55～60HRC)
pose taps for thermal refined steels
should be selected.
When tapping stainless steels, prob-
lems may occur like torn threads or
Stainless material welding over the tap.
SU-HT Stainless steels OX ～5
steels Chips are rather hard and tended
to be extended in length. This can
cause chip ejection problems.

15
 Recom- Recom-
mendation Surface mended
Material Features of material Purpose/Spec.
by YAMA- treatment speed
WA (m/min)

The tap is prone to wear when FC-HT For cast irons NI

cutting cast iron. Chip welding Carbide taps for
N-CT FC - 5～15
problems occur and the NG cast irons
screw thread gauge problems
Cast irons tend to be an issue from tool Ultra fast tapping,
HFICT-B Coating 20～50
wear. Cast iron produces pow- blind hole use
dery chips, while ductile iron
has a tendency to produce Ultra fast tapping,
HFICT-P Coating 20～50
longer chips. through hole use

For Aluminum die-

LA-HT NI 5～15
These materials have a melting casting
point that easily causes chip
welding problems on taps. AXE-HT AXE Coating 10～20
They are soft and sticky materi-
Wrought Alu-
als. Carbide taps hav-
minum, Alumi-
Unless you use the tap with high HFACT-B ing coolant hole Coating 30～100
num die-
cutting performance and high For blind hole use
castings
geometry, you may easily cre-
ate torn threads in your internal
threads. Materials shrinkage Carbide taps hav-
problems occur easily in internal ing coolant hole
HFACT-P Coating 30～100
threads. For through hole
use

The free machinability of this

material is relatively good, but it
is soft and flows freely so it is
Coppers・ Carbide taps for
easy for internal threads to be N-CT FC - 5～15
Brass cast irons
created. Tap welding problems
and internal thread shrinkage
problems tend to occur easily.
It is easy to melt this material
even at low temperatures be-
Thermosetting cause it is soft. It is necessary to For thermosetting
PL1 NI 5～10
Plastic use a tap with good cutting ge- plastics
ometry. Internal threads have a
high shrink ability.
The material is easy to cut but
fine chips can ignite. Pay atten-
Magnesium tion to the heat of the chips.
MG-HT For Magnesium - 5～15
Alloy Castings These materials are inferior in
cold processing, so we do not
recommend roll tapping.

16
Introduction of RE-HT

17
18
19
Introduction of UH-CT/EH-CT

20
21
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 “Understanding the basics” series

“How to refer YAMAWA product catalog”

Please confirm the details from below link.

http://www.yamawa.com/jp/support/catalog/pdf/tips.pdf

YAMAWA introduces important tips about YAMAWA products

while answering frequently asked questions by many of our
customers.
After reading these topics, we are sure you will find how easy and
understandable the technique are. Please check the link below.

http://www.yamawa.com/jp/support/tips/index.html

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