CNC Services Northwest

Centroid CNC control sales, service, training and support

Finding the distance for one motor turn

In troubleshooting possible encoder or home switch problems on a Centroid-controlled machine tool, it is helpful to know how much axis movement corresponds to one turn of the servo motor.

You can find this information on the Machine Configuration screen.

Press F1 for Setup
Press F3 for Config
At the Password prompt, Enter "137"
Press F2 for Machine Configuration
Press F2 for Motor Parameters
Look in the second column, "Motor Revs/Inch" (or "Revs/mm")
This tells how many turns of the motor are required to move one real-world unit (inch, millimeter, or degree on rotary axes).
The amount of movement per motor turn is simply the reciprocal of the number on the screen. See the table below for common examples.
Press ESC four times to return to the main screen

Typical Inch Ratios

Revs/Inch	Inches/Rev
5.00	0.2000
5.08	0.1969
7.50	0.1333
7.62	0.1312
8.0433	0.1243
10.00	0.1000
10.16	0.0984

Typical Metric Ratios

Revs/mm	mm/Rev
0.1969	5.080
0.2000	5.000
0.2953	3.387
0.3000	3.333
0.3167	3.158
0.3937	2.540
0.4000	2.500

Typical Rotary Table Ratios

The column heading on the Machine Configuration screen will always say "Revs/inch" or "Revs/mm" even if one or more axes is rotary, commanded in degrees. The value in the table, however, will be motor turns per degree.

Gearbox Revs/degree Degrees/Rev

72:1 0.20 5.00

90:1 0.25 4.00

180:1 0.50 2.00

360:1 1.00 1.00

Gearbox	Revs/degree	Degrees/Rev
72:1	0.20	5.00
90:1	0.25	4.00
180:1	0.50	2.00
360:1	1.00	1.00

CNC Services Northwest Home