






BACK to
USE and CARE







GAGE BLOCK HEADER PAGE


How to Select Gage Blocks for Use
in Combinations


Gage block selection is a process that starts by examining the last or smallest decimal place
of the desired combination and eliminating it while subtracting it from the remaining length of
the desired combination as you proceed. The process is repeated for each remaining decimal
place until the total combination has been selected.
As an example: A desired combination is to have a length 3.9762 in.
1) Look over the available blocks in the set for a block that has a "2" in the fourth decimal
place. Most likely it will be a .1002" block. (Some sets will have a .0502" block.)
2) Subtract the selected block from the total length of the desired combination to eliminate the
last decimal place.



81 piece set

36 piece set

.050 series set

3.9762
 .1002
3.876x

3.9762
 .1002
3.876x

3.9762
 .0502
3.926x




3) Now examine the next smallest decimal place. (In this example, it ends with a "6".) Find
the blocks in the set that have a "6" in the third decimal place:



81 piece set

36 piece set

.050 series set

.106
.116
.126
.136
.146

.106
.

.056
.





If you are using an 81 piece set, choose the block that will leave either a "0" or a "5" in the
second decimal place when you subtract this block from the result in Step 2. (In this
example, it would be the .126" block.)
4) Subtract the selected block from the result in Step 2.






5a) If you are using an 81 piece set, the selection is about done. It can be seen from the
remainder in Step 4 above that a .750 and an 3.000 inch block will complete the
combination. Proceed to Step 10.
5b) If you are using a 36 piece set or a .050 series set, you must continue to examine the
smallest remaining decimal place of the result. Choose the block in the set that will
eliminate the last nonzero decimal place. (In this example, the last decimal place
contains a "7".)




36 piece set

.050 series set


Choose: .170 block

Choose: .070 block




6) Subtract the chosen block from the remaining result in Step 4.





36 piece set

.050 series set


3.770
 .170
3.6x

3.870
 .070
3.8x



7) Examine the last remaining nonzero decimal point. Smaller sets do not usually have a .600
or .800 inch blocks. These sets usually contain these sizes:
.100
.200
.300
.400 (May or may not be included in the set)
.500


8) Choose blocks from the series of blocks listed in Step 7 above that will add up to the
remaining decimal place calculated in Step 6. In this example, the choices would probably
be:





36 piece set

.050 series set


Choose: .100 block
.500 block

Choose: .300 block
.500 block





Note: Other choices could be made as shown below. But, it is recommended to keep the
number of blocks in the combination as small as possible.




36 piece set

.050 series set

Alternate choice:
(Not recommended)

Choose: .100 block
.200 block
.300 block

Choose: .100 block
.200 block
.500 block




9) Now that all that remains is the whole number of inches in the combination. (3 inches in the
example.) If the set has a single block of the desired length, choose it. Otherwise, a
combination of blocks will have to be selected. In our example, it is more likely that the
3inch size will have to be built up from 1inch and 2inch blocks.




36 piece set

.050 series set


Choose: 1.000 block
and 2.000 block

Choose: 1.000 block
and 2.000 block





10) Double check the combinations by adding together all the selected blocks.



81 piece set

36 piece set

.050 series set

.1002
.126
.750
3.000
3.9762

.1002
.106
.170
.100
.500
1.000
2.000
3.9762

.0502
.056
.070
.300
.500
1.000
2.000
3.9762







Metric gage block selection is performed in the same manner. Always start with the last or
smallest decimal place and eliminate it with your choice of blocks while you subtract it from
the remaining length of the combination as you proceed. Repeat this procedure until the total
combination has been selected.
Example: Desired combination length of 150.932mm
1) Examine the blocks in the set that have a "2" in the third or lowest decimal point.





piece sets


ce sets

1mm base set

2mm base set

1mm base set

2mm base set

1.002 block

2.002 block

1.002 block

2.002 block




Choose:


2) Subtract the chosen block from the size of the desired combination.




piece sets


ce sets

1mm base set

2mm base set

1mm base set

2mm base set

150.932
 1.002
149.93x

150.932
 2.002
148.93x

150.932
 1.002
149.93x

150.932
 2.002
148.93x




3) Choose a block to eliminate the next smallest nonzero decimal point. If using an 88 or 112
piece set, choose a block that will leave either a "0" or a "5" in this decimal place.


Choose:





1.43 block

2.43 block

1.03 block

2.03 block



4) Subtract the chosen block from the remainder in step 2.





piece sets


ce sets

1mm base set

2mm base set

1mm base set

2mm base set

148.93
 1.43
148.5x

148.93
 2.43
146.5x

149.93
 1.03
148.9x

148.93
 2.03
146.9x



5) Choose block to eliminate the next smallest nonzero decimal point. If using an 88 or 112
piece set, choose a block that will eliminate the first whole millimeter decimal place as
well.


Choose:






8.5 block

6.5 block

1.9 block

2.9 block



6) Subtract the chosen block from the remainder in step 4.





piece sets


ce sets

1mm base set

2mm base set

1mm base set

2mm base set

148.5
 8.5
140.x

146.5
 6.5
140.x

148.9
 1.9
147.x

146.9
 2.9
144.x



7) Choose blocks to equal the whole millimeters left in the combination.







ce sets

112 piece set

88 piece set

1mm base set

2mm base set

100.0
25.0
15.0

100.0
40.0

90.0
50.0
7.0

90.0
50.0
4.0



8) Verify that the combination of chosen blocks equals the desired length.





piece sets


ce sets

1mm base set

2mm base set

1mm base set

2mm base set

1.002
1.43
8.5
100.0
25.0
15.0
150.932

2.002
2.43
6.5
100.0
40.0
150.932

1.002
1.43
1.9
90.0
50.0
7.0
150.932

2.002
2.03
2.9
100.0
25.0
15.0
150.932



BACK to
USE and CARE


GAGE BLOCK HEADER PAGE



GB49


©2018, Webber Gage Division, The L. S. Starrett Co, Westlake, Ohio , 44145































