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B89.1.9-2002 Size Tolerances----Webber Grades
Tolerances are in microinches or (micrometers).
Webber
Grade -->

B89 Grade
Order
.
.
B89
Webber 
.
.
Grade
Grade AA
.
.
00
Order 
.
.
B89
Webber 
.
.
Grade
Grade A1
.
.
0
Not
.
.
B89
Available
.
.
Grade
.....
.
.
AS1
Not 
.
.
B89
Available
.
.
Grade
.....
. 
. 
AS2

.
Size
Tolerance
Variation
in
Length
Flatness
Size
Tolerance
Variation
in
Length
Flatness
Size
Tolerance
Variation
in
Length
Flatness
Size
Tolerance
Variation
in
Length
Flatness
Thru .050 in.
    (0.5mm)
+4 / -4
(+.10 / -.10)
2
(.05)
2
(.05)
+6 / -6
(+.15 / -15)
4
(.10)
4
(.10)
+12 / -12
(+.30 / -.30)
6
(.16)
6
(.15)
+24 / -24
(+.60 / -.60)
12
(.30)
10
(.25)
Thru .400 in.
   (10.0mm)
+3 / -3
(+.07 / -.07)
2
(.05)
2
(.05)
+5 / -5
(+.12 / -.12)
4
(.10)
4
(.10)
+8 / -8
(+.20 / -.20)
6
(.16)
6
(.15)
+18 / -18
(+.45 / -.45)
12
(.30)
10
(.25)
Thru 1.000 in.
   (25.0mm)
+3 / -3
(+.07 / -.07)
2
(.05)
2
(.05)
+6 / -6
(+.15 / -15)
4
(.10)
4
(.10)
+12 / -12
(+.30 / -.30)
6
(.16)
6
(.15)
+24 / -24
(+.60 / -.60)
12
(.30)
10
(.25)
Thru 2.000 in.
   (50.0mm)
+4 / -4
(+.10 / -.10)
2
(.06)
2
(.05)
+8 / -8
(+.20 / -.20)
4
(.10)
4
(.10)
+16 / -16
(+.40 / -.40)
6
(.18)
6
(.15)
+32 / -32
(+.80 / -.80)
12
(.30)
10
(.25)
Thru 3.000 in.
   (75.0mm)
+5 / -5
(+.12 / -.12)
3
(.06)
Rect 2  (.05)
Sqr  3  (.07)
+10 / -10
(+.25 / -.25)
4
(.12)
4
(.10)
+20 / -20
(+.50 / -.50)
6
(.18)
6
(.15)
+40 / -40
(+1.0 / -1.0)
14
(.35)
10
(.25)
Thru 4.000 in.
   (100.0mm)
+6 / -6
(+.15 / -15)
3
(.07)
Rect 2  (.05)
Sqr  3  (.07)
+12 / -12
(+.30 / -.30)
5
(.12)
4
(.10)
+24 / -24
(+.60 / -.60)
8
(.20)
6
(.15)
+48 / -48
(+1.2 / -1.2)
14
(.35)
10
(.25)
Thru 5.000 in.
   (125.0mm)
+8 / -8
(+.20 / -.20)
3
(.08)
Rect 2  (.05)
Sqr  3  (.07)
+16 / -16
(+.40 / -.40)
5
(.14)
4
(.10)
+32 / -32
(+.80 / -.80)
8
(.20)
6
(.15)
+64 / -64
(+1.6 / -1.6)
16
(.40)
10
(.25)
Thru 6.000 in.
   (150.0mm)
+8 / -8
(+.20 / -.20)
3
(.08)
Rect 2  (.05)
Sqr  3  (.07)
+16 / -16
(+.40 / -.40)
5
(.14)
4
(.10)
+32 / -32
(+.80 / -.80)
8
(.20)
6
(.15)
+64 / -64
(+1.6 / -1.6)
16
(.40)
10
(.25)
Thru 7.000 in.
   (175.0mm)
+10 / -10
(+.25 / -.25)
4
(.09)
4
(.10)
+20 / -20
(+.50 / -.50)
6
(.16)
6
(.15)
+40 / -40
(+1.0 / -1.0)
10
(.25)
7
(.18)
+80 / -80
(+2.0 / -2.0)
16
(.40)
10
(.25)
Thru 8.000 in.
   (200.0mm)
+10 / -10
(+.25 / -.25)
4
(.09)
4
(.10)
+20 / -20
(+.50 / -.50)
6
(.16)
6
(.15)
+40 / -40
(+1.0 / -1.0)
10
(.25)
7
(.18)
+80 / -80
(+2.0 / -2.0)
16
(.40)
10
(.25)
Thru 10.000 in.
   (250.0mm)
+12 / -12
(+.30 / -.30)
4
(.10)
4
(.10)
+24 / -24
(+.60 / -.60)
6
(.16)
6
(.15)
+48 / -48
(+1.2 / -1.2)
10
(.25)
7
(.18)
+104 / -104
(+2.4 / -2.4)
18
(.45)
10
(.25)
Thru 12.000 in.
   (300.0mm)
+14 / -14
(+.35 / -.35)
4
(.10)
4
(.10)
+28 / -28
(+.70 / -.70)
7
(.18)
6
(.15)
+56 / -56
(+1.4 / -1.4)
10
(.25)
7
(.18)
+112 / -112
(+2.6 / -2.6)
20
(.50)
10
(.25)
Thru 16.000 in.
   (400.0mm)
+18 / -18
(+.45 / -.45)
5
(.12)
4
(.10)
+36 / -36
(+.90 / -.90)
8
(.20)
6
(.15)
+72 / -72
(+1.8 / -1.8)
12
(.30)
7
(.18)
+144 / -144
(+3.6 / -3.6)
20
(.50)
10
(.25)
Thru 20.000 in.
   (500.0mm)
+20 / -20
(+.50 / -.50)
6
(.14)
4
(.10)
+44 / -44
(+1.1 / -1.1)
10
(.25)
6
(.15)
+88 / -88
(+2.2 / -2.2)
14
(.35)
7
(.18)
+176 / -176
(+4.4 / -4.4)
24
(.60)
10
(.25)
The B89.1.9 standard became effective in July, 2002.   On January 6, 2003, Webber began to sell gage blocks to the new 
B89.1.9-2002 standard.  The Federal standard, GGG-G-15C, has been withdrawn. 

Webber Gage will continue to sell individual blocks and sets to the obsolete GGG standard.
However a 10% surcharge will apply to the order and the purchase orders must specify compliance to GGG-G-15C.  
Orders submitted to Webber that state only a catalog number will be filled using the new B89.1.9 tolerances. 

Suggested replacements for the old GGG-G-15C grades are as follows: 
GGG-G-15C Grade
Webber Grade
B89 Grade
Grade 1
AA
00
Grade 2
A1
0
Grade 3
---
AS1
---
---
AS2
The B89.1.9 standard also contains a special grade of block, Grade K.  This grade of block is meant to be used as reference masters in
calibrations where compensations to the deviations of the masters are applied.  The geometry of the blocks (flatness and parallelism) are
tightly controlled to minimize measuring errors.  The size tolerances are the same as B89.1.9 Grade AS1, but the tolerances for flatness
and variation in length (parallelism) are similar to Grade 00.

Webber Gage does not specifically manufacture Grade K blocks. If Grade K blocks are required, please order Webber Grade AA blocks
and specify compliance to Grade K on the purchase order.
To Display Tolerances for the old GGG-G-15C specification, Click Here.
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