39
NOTICE
17. Indexing Accuracy and Pitch Error
“ What is the linear length at the table circumference with
20 seconds cumulative indexing accuracy ?”
“ What is the angle with a cumulative pitch error of
0.01mm ?”
To answer these questions, use the following formula
representing the relationship between the angle and linear
length at the table circumference.
D： Diameter of Workpiece (mm)
α： Angle (seconds)
L： Linear length at the table circumference (mm)
(1)
"60'60360
･･････････････････････････････ ･････････
××°
=
×
π
D
L
(2)
10125.46060360
5
････････ ･･････････ ･････････
D
L
D
L ××
=
×
×××
=
π
α
(3)10424.2
6060360
6
･･･････ ･･････････ ･････････D
D
L ×××=
××
××
=
−
α
(Examples)
Assuming the diameter of the workpiece is 100mm, and by using formula (2), the
cumulative indexing accuracy of 20 seconds as linear length at table circumference will be：
mmL 004848.01010020424.2
6
=×××=
−
Therefore, the length is approximately 0.0048mm.
And converting the cumulative pitch error of 0.01mm to an angle, use formula (3)：
"25.41
100
1001.0125.4
5
=
××
=
α
Therefore, the angle is approximately 41 seconds.
Thus, by using the formula (2) and (3), the indexing precision and pitch error can be
converted in terms of linear length and angle.
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