GDT
GDT
GDT
Originated by:
Date Issued
XX +/- 0.05
0.2 M A
XX 0.05
25
A2
B
25
A1
Originated by:
25
A3
Date Issued
I.
SCOPE:
This specification is issued to provide generic General Notes for detail drawings and data
files of sheet metal parts and assemblies.
II.
APPLICATION:
Notes: are to be used for sheet metal details and for assemblies when specified.
Tolerances that are unique from those below are to be shown on the face of the drawing or
on the Format #2 of the data files.
III.
Originated by:
Date Issued
SECONDARY DATUM
The fourth box contains the
secondary datum and is generally
a 4 way locating hole modified at
MMC taken from section V, B)
I V.
Tolerance
GEOMETRIC CONTROL
The first box contains one of
the following geometric
controls
0.5
Tertiary Datum
Control
Primary Datum
Perpendicularity
Position
Profile of a Surface
Profile of a Line
TERTIARY DATUM
The fifth box contains the tertiary
datum and is generally a 2 way
locating slot modified at MMC taken
from section V, C)
TOLERANCE ZONE
The second box contains the
tolerance zone shape, size
and any applicable material
modifier (usually MMC)
Originated by:
PRIMARY DATUM
The third box contains the
primary datum which is
generally a planer datum
simulated by three or more
datum targets
Date Issued
IV. CONTINUED
The material modifier used will be M (maximum material condition), when features of size
are used as secondary and tertiary features.
Secondary Datum
A B
Tertiary Datum
Primary Datum
There are several advantages of applying the MMC to the secondary and tertiary datum features of size (hole / slot).
It allows the use of fixed (virtual condition) pins in the manufacturing and gaging equipment. Because of the tight size tolerance (+/- 0.05) of
these datum features, the datum displacement (shift) is minimal.
The other material modifiers available are regardless of feature size RFS and least material condition LMC. These modifiers are not
recommended for the following reasons:
RFS (regardless of feature size ) requires a moveable fixture i.e. a spring loaded tapered pin (for holes) and a spring loaded diamond pin (for
slots). It is expensive to verify, and rarely reflects the relevant feature function, and therefore should not be used in a Body application without
the agreement of the entire core team.
LMC (least material condition) is expensive to verify. To date no application in the Feature Control Frame for this symbol has been identified in
Body Engineering.
Originated by:
Date Issued
V.
The most restrictive
tolerance is the default
Size tolerance for any shape hole used as a secondary or tertiary (locator)
feature be +/- 0.05.
Size tolerance for any shape hole used as a transferred locator be +/0.05.
All other size tolerances to be +/- 0.4 with the exception: All lightening,
access, and drainage holes are to be:
Originated by:
Date Issued
SECONDARY DATUM
Generally a hole is used as a Secondary Datum and
functions as a 4 way locator
V. HOLES: CONTINUED.
B)
The positional tolerance of the secondary datum feature in relation to the primary datum to
be:
XX 0.05
The asterisk
refers to the
description of 0
@ MMC
tolerancing
addressed at the
end of the 1294
section VII.
Size tolerance
taken from
section V.
HOLES: A)
Originated by:
Date Issued
TERTIARY DATUM
Generally the width of a Slotted Feature of Size is used as a
Tertiary Datum and functions as a 2 way locator to stop rotation
V. HOLES: CONTINUED.
C)
The positional tolerance of the tertiary datum feature in relation to the primary and
secondary datums is to be:
XX +/- 0.05
0.2 M A
0.2 total width zone (no
diameter symbol shown)
XX +/- 0.05
0.2 M A B M C
Primary and
secondary
Datum required
If applied on the face of
the drawing a Datum
Feature symbol would be
used
Originated by:
Date Issued
A B
9.95
0.20
9.75
13.95
0.20
13.75
14 +/- 0.05
0.2
A B
Datum plane A
XX
THIS CONTROL
MEANS THIS
POSSIBLE LMC SLOT ORIENTATION
9.95
0.20
9.75
13.95
0.20
13.75
Originated by:
Date Issued
Secondary Datum
Virtual Condition "Pin For Datum
Feature B" is equal to the holes MMC
Size. (since the hole is toleranced at 0
at MMC its virtual condition size is the
MMC limit)
Tertiary Datum
Virtual Condition "Race Track Pin For Datum
Feature "C" is equal to the slots MMC Size
Minus the Positional Tolerance.
Originated by:
10
Date Issued
XXX
Nominal location of center plane of
hole / slot and pins in the mating part
Originated by:
11
Date Issued
locate components assembled in a fixture , i.e. locate individual components to create an assembly to be welded together (see
fig. 1)
locate mating parts in the assembly. i.e. locate a trim panel for proper assembly (see fig. 2)
They typically consist of a combination hole / slot, a pair of holes or a pair of slots.
They are generally toleranced in relation to the global datum reference frame (master control holes).
2-WAY
LOCATOR PIN
4-WAY
LOCATOR PIN
2-WAY
FABRICATION
HOLE
4-WAY
FABRICATION HOLE
fig. 2
fig. 1
Originated by:
12
Date Issued
0.5
A B
Width
1.6
A B
Length
10 +/- 0.05
0.5 M A B M C M
14 +/- 0.4
1.6 M A B M
Originated by:
0.5 M A B M C M
A B
0.5
10 +/- 0.05
C M
XX
13
Date Issued
V. HOLES: CONTINUED.
POSITIONAL TOLERANCE OTHER HOLES
Holes other than secondary, tertiary and
locator are considered non critical and have a
general tolerance of 1.6 for location. All other
non critical holes such as lighting, access and
drainage are toleranced using profile of a line
and will be covered under the profile section.
E)
1.6
A B
A B
A B
For slots:
1.6
1.6
Width
Length
A B
10 +/- 0.4
1.6 M A B
Originated by:
14
A B
Date Issued
V. HOLES: CONTINUED
The positional tolerance of group of holes and tolerance between all holes that are
labeled or dimensioned as a group to be:
1.6
0.5
M
M
A B
A
Originated by:
15
Date Issued
3X 20 +/- 0.4
1.6
0.5
M
M
A B
A
THIS CONTROL
M
Actual Hole
Basic dimension
Basic dimension
25.0
Originated by:
MEANS THIS
25.0
16
Date Issued
1.4
A B
Originated by:
17
1.4
Date Issued
A B
10
5
0 5
10
5
0 5
10
10
90
The Tolerance establishes a
uniform two-dimensional zone
limited by two parallel zone lines
extending along the length of
the considered feature.
Originated by:
3 (Bilateral)
18
Date Issued
V. SURFACES:
A)
1.4
A B
B)
Lines and surfaces defining mating conditions shown in sections are to be:
1.4
A B
Profile is only applied on one side of metal. On a standard dimensioned drawing the dimensions are
applied to the design / dimensioned side (the punch side). The opposite side of metal is controlled by the
sheet metal stock size tolerance.
Originated by:
19
Date Issued
THIS CONTROL
If displayed on a drawing
the arrow points to the
design / dimension side
of the surface
A B
Metal thickness
XX +/- XX
MEANS THIS
Originated by:
3
Tolerance zone boundary
1.5
20
Date Issued
Depending on application,
the all around may be
applied. The All around
symbol (a circle located at
the junction of the leader)
indicates that the profile
tolerance applies all around
the feature.
V.
SURFACES:
C)
A B
0.5 / 250
1 A B
0.5 / 250
250
0
25
Originated by:
21
Date Issued
THIS CONTROL
If displayed on a drawing
the arrow points to
margin line edge of the
surface
1 A B
0.5 / 250
MEANS THIS
True Basic Profile of
component edge
0.5
250
250
250
250
1
Entire surface must lie between a profile boundary of 1
(Zone is equally disposed about basic contour +/- 0.5)
Originated by:
22
Date Issued
V. SURFACES: CONTINUED
D)
A B
0.5 / 250
ALL OVER
Originated by:
23
Date Issued
A B M C
0.5 / 250
SURFACE FLUSHNESS
Surface flushness
of controlled
surface
THIS CONTROL
MEANS THIS
0
25
25
0
A B M C
0.5 / 250
Originated by:
0
25
24
Date Issued
THIS CONTROL
If displayed on a drawing
the arrow points to the
design / dimension side
of the surface
A B M C
0.5 / 250
ALL OVER
Opposite side of
metal controlled by
metal thickness
MEANS THIS
Metal thickness
XX +/- XX
As a refinement within
the larger 1 zone, all
elements of the surface,
adjacent to the edge
must lie between a
boundary of 0.5 within
any unit area 250 X 250
250
Opposite side of
metal controlled by
metal thickness
Originated by:
25
0.5
Date Issued
V. SURFACES: CONTINUED
E)
A B
Originated by:
26
Date Issued
V.
LINES:
A)
3
B)
A B
C)
Datum lines, work lines and body grid lines are +/- 0. Tolerance between the above lines not
permissible.
Datum lines, work lines and body grid lines are often shown as
reference information and are treated as theoretically exact.
A B
Depending on application,
the all around may be or
may not apply.
Basic contour shown
Originated by:
27
Date Issued
THIS CONTROL
A B
MEANS THIS
Originated by:
3
Actual Surface edge must lie
within Tolerance Boundary
28
Date Issued
V. HOLES: A)
Secondary Datum
V. HOLES: B)
V. SURFACES: A)
XX 0.05
0
A B
1.4
A B
V. LINES: A)
V. HOLES: A)
Tertiary Datum
XX +/- 0.05
5
A B
0.2
25
A1
V. HOLES: A) OTHER
V. HOLES: A)
Tertiary Datum
V. HOLES: C)
XX +/- 0.05
0.2
XX +/- 0.4
1.6
A B
V. HOLES: C)
2X XX +/- 0.4
V. HOLES: E)
25
A2
1.6
0.5
25
A3
Originated by:
29
M
M
A B
A
V. HOLES: F)
Date Issued
VI.
The positional tolerance of the secondary datum in relation to the primary datum to be:
XX 0.05
0
Originated by:
30
Date Issued
VI.
The positional tolerance of the tertiary datum feature in relation to the primary and
secondary datums is to be:
XX +/- 0.05
0.2 M A
Originated by:
31
Date Issued
VI.
2.0
2.0
A B
A B
Positional
between
datum / locator
holes.
Positional between
datum / locator
holes and slots
Originated by:
32
Date Issued
0.21
XX 0.05
2.0 M
XX 0.05
2.0
XX 0.05
M
2.0 M
DETAIL 3
2.0
DETAIL 2
G
DETAIL 1
ASSEMBLY
XX 0.05
0.29
0.2 M
XX 0.05
0.0 M
A
C
DETAIL 3
DETAIL 2
DETAIL 1
ASSEMBLY
A
Originated by:
33
Date Issued
VI.
1.4 A B
0.5 / 250
Originated by:
34
Date Issued
VI.
A B
0.5 / 250
ALL OVER
Originated by:
35
Date Issued
XX 0.05
0
XX +/- 0.05
0.2 M A
Secondary Datum
orientation tolerance
taken from section VI. A)
A B
0.5 / 250
Tertiary Datum
Position tolerance
taken from
section VI. B)
25
A3
25
A1
XX +/- 0.05
0.2 M
1.4 A B
0.5 / 250
25
A2
Originated by:
Position tolerance
taken from
section VI. B)
36
Size tolerance
taken from section
V. HOLES: A)
Date Issued
VII.
Originated by:
37
Date Issued
END
Originated by:
38
Date Issued