Also mostly as others said later.
The spindle feed / speed like threading depends on the plugin and hw you have.

So my csmcio-ip-s results will not be the same as yours, or the centipede I had in the past, or the smoothstepper early version.

And inputs from analog sources may be accurate, as regards relative spindle speed, but equally may not be accurate.
I tested this really well with Sergey who developed the centipede.
We proved very clearly that most index signals, single pulse, are not too good and reliable and crisp.
He developed a specific board for that, to make a single crisp reliable pulses.
This was several years ago.

My lathe now uses industrial servos at 1:3 belt drive, HTD 8 MM x 30 mm, 1:3.
The controller csmcio-ip-s can read them, from servos with 10.000 counts/turn.
The readout fluctuates +/- 1 rpm, which is an error in csmcio plugin.
Itīs still extremely accurate.

The spindle speed is still extremely accurate.
About 0.01 rpm accurate in fact.


This wont be of much use to You, as mach results depend on the controller and or hw you have.

Quote Originally Posted by John11668 View Post
Background .
I converted a Boxford TCL lathe to Mach 3 but retained the DC Spindle motor, and Lenze controller with Iso Board.

Had a bit of trouble getting the spindle index function sorted but thanks to some help from folks on here (you know who you are) I now have a very accurate "true spindle " readout which corresponds well with a mechanical tachometer .
And with spindle speed set to 2000 the analog signal generated by the pwm output is 9.6 v and reduces more or less in proportion to selected spindle speed so that looks fine .

Now I know that this is actually the motor speed , and the true spindle speed will vary according to the pulleys in use at any time , and that I need to select a number for the pulley setting along with the ratio of the selected pulley combination.
But if I change the ratio in spindle pulleys (and I have tried varying ratios from 1 to 8) but this has no effect at all upon true spindle speed .
In addition whatever spindle pulley number I select the display continues to show S1

I have looked for other related settings but dont see any which are relevant. I have read the manual and although there is a section on pulleys and the need to specify the ratios I dont see any guidance on other settings
What might I be missing.
Suggestions anyone ?