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Adjusting
Vernier Scale
A vernier scale is used to improve the precision
of reading an instrument scale for more accurate
milling operations.
The handwheel dial is marked in degrees with
divisions in 2 minutes (2'). The vernier scale
graduations are represented in 20 seconds (20")
(see Figure 20A).
When the handwheel is rotated clockwise, gradu-
ations to the left of the "0" on the vernier scale
are used. When the handwheel is rotated coun-
terclockwise, graduations on the right hand side
are used.
We will be setting the table to 16˚ 10' 40" in the
first example below. This exercise assumes the
table position starts at 0˚, as read on the angle
scale on the edge of table, and that "0" on the
handwheel dial and "0" on the vernier scale are
aligned. For these instructions, refer to Figure 20.
Example 1:
1.
Rotate handwheel clockwise 4 times. Watch
for "0" marker on handwheel dial and slow
down rotation as "0" comes into view for 4
time. Stop on the "0" when "0" on handwheel
dial aligns with "0" on vernier. You are at 16°
(see Figure 20A).
2.
Now rotate handwheel clockwise 5 gradua-
tions to align with "0" on vernier scale. You
are now at 16° 10' (see Figure 20B).
3.
Two graduations to left of zero on vernier
scale is the 40" mark, as highlighted in Figure
20B. Rotate handwheel clockwise slightly to
align first graduation on handwheel dial on
left side of 40" mark with 40" on vernier, as
shown in Figure 20C. You are now at 16° 10'
40".
Note: The handwheel should not be rotated
past this point. If it is, rotate it counterclock-
wise one full turn and "sneak" up on mark
again. Once you are satisfied with table posi-
tion, lock it in place with table locks.
Model T25937 (Mfd. Since 3/16)
Vernier
A
30
B
th
C
Figure 20. Vernier scale adjustments.
Continued on next page
60
0
60
Handwheel
0
30
60
0
60
30
0
30
60
0
60
30
0
30
-15-
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