lathe speed S and STrue wildly different...

[nate]

I am running a stepper as a spindle motor and I cannot get the darn thing set up correctly.

Here is my setup-

Mach3
Smooth Stepper
200 step/rot pacsci 870 oz in motor.
14-44 tooth gear reduction. 1 : 3.181 Ratio
Gecko 203V
CNC4PC optical tach

I cant seem to get a steady tach reading under 175RPM. I am not sure what appropriate debounce seetings might be.

I have tried tons of settings under 'spindle pulleys' and 'motor tuning/spindle' and for the life of me I cant seem to get the motor to turn 1000rpm when I type in S1000.

This should be simple right? at 200steps/revo, with a 1:3.181 Ratio, I should have 636.2 steps/revo. then I set my pully ratio to 1:1, set my min/max speeds, set velocity and accell and...theoreticlly, I should have accurate control of my spindle. well, suffice it to say that it does not work the way I imagine it should...nothing jives.

Anyone have any insight? I have been trying to figure this out for over a year off and on, and I am reaching a new level of frustration...

Thanks,
Nate.

[nate]

Here is an example of what I am getting given a particular set of seetings.

Motor Tuning
Steps 6362
speed 100
Accel 10

Spindle pulleys
Min speed 0
max speed 3000
Ratio 1

With these settings, I get these results-
STrue 101
S 3000


I hope this example will help someone help me pinpoint the problem. I am at a loss and would really like a hand...

Best,
Nate.

[Hood]

Set spindle pulley Max to the same as the Velocity in Motor Tuning.
Hood

[Hood]

BTW with a stepper you are probably looking at around 1000rpm motor revs max and with the gearing that would mean probably about 300 spindle RPM.
Hood

[nate]

Originally Posted by Hood BTW with a stepper you are probably looking at around 1000rpm motor revs max and with the gearing that would mean probably about 300 spindle RPM. Hood

sure, thats fine by me. this is just for threading and light indexing work like milling flats.

For normal turning I use a VFD and invertor duty motor.