I'm not convinced by the spindle rated

0rpm to 24,000 rpm, not by the upper rpm, but the lower RPM.

Power is a function of torque and rpm, same torque, higher rpm = more power.

A quick calculator here:

http://www.wentec.com/unipower/calculat ... torque.aspLets presume your spindle is 100% efficient (it avoids splitting hairs and arguing the toss if its 60, 70, 80 % efficient.... but you'll find the higher the RPM the lower your efficiency because of motor losses, drag on the bearing etc), efficiency also has a "sweet spot" so it won't have a higher efficiency at the lowest speed, its normally ~2/3rds in the rpm range where peak efficiency is hit

Therefore a 1.5kW rated spindle can only ever develop 0.6 n.m. (5.28 lb.in) of torque

So at 500 rpm it can at most develop 30 watts of power, and at 1000rpm 60 watts of power etc.

There was some discussion here about minimum spindle speed, and I thought it would be about the 6000 to 8000 rpm range.

https://www.cnczone.com/forums/spindles ... speed.htmlSo if it was me, I'd set it up like this and see how it goes (the reason being is it will give your PWM signal a more defined range from 0% to 100% = say 6000 rpm to 24000 rpm which means that at 6000 rpm, the spindle motor is looking for 100hz, and will produce (at most) 380W (25% of motor rated output power)

I found "

A" manual here for your drive (I'm not sure if it ACTUALLY is).... its just a Nowforever VFD {check the model numbers}

https://www.docdroid.net/NYibeDM/nowfor ... df#page=39P0-008 = 100Hz (6,000 rpm)

P0-007 = 400Hz (24,000rpm)

P0-022 = 100hz (6,000rpm)

P0-024 = 400hz (24,000rpm)

You may also want to consider calibrating P0-021 and P0-023 to the range of the analog input signal to the VFD.... sometimes the output from some PWM to analog signal converter devices / circuits is non linear (i.e. they can only give a maximum output of 9.6V..... in this case I would change P0-023 to 9.60). Note: P0-021 and P0-023 are to two decimal places..... Ie in theory they have 1000 steps from 0.00v to 10.00, and your spindle has to ramp from 0rpm (or 6000 rpm if you set it up as I've suggested) to 24,000 rpm, so the increments will be 24rpm / step (or 18 rpm per step if setup as per my suggestion), hence some degree of calibrantion is recommended. The best way to do this calibration would be with a spindle trigger signal so that the actual spindle speed can be read within UCCNC and then you adjust the Po-021 and P0-023 when the spindle speed is set to minimum and maximum, and you adjust P0-021 / P0-023 in small increments to see if the actual spindle speed that way you find the exact range point. Measuring the voltage is not always the best way.... given the voltmeter and the VFD input may not be calibrated and may be reading the voltage differently.

Then I'd change the UCCNC spindle settings as attached screenshot.

Note: You will also have to change P0-002 (or P0-003 I can't understand the manual that well) to AIN1 (setting 2) or AIN2 (setting 3) depending upon which one you are using for your speed input from the gecko

Check you have the input terminals defined correctly to accept the M3 start signal from UCCNC via the gecko (P0-016, P0-017, P0-018 or P0-019, which ever one you are using as the spindle run signal (setting 1)