Need a little advice

[Jmh474]

Good afternoon all so I'm in the building a cnc router and I would like to use a program to control the speed of the spindle, now the spindle I have is controlled by a Potentiometer and the controller uses pwm iv brought a pwm to voltage converter.

Dose anyone have any ideas on the best way to maybe get this to work?

[beanflying]

Last time I saw someone put some numbers at the potentiometer on that combination it was in the order of 70-90V (from memory) so it is not that trivial to drive it from your CNC board.

The nuts and bolts of it is it is possible but you will need a daughter board more than likely to take a PWM signal from your controller which will be set by GCode and then turn that into the appropriate voltage the power supply speaks.

Unless someone has already done it we will be flying blind without a lot more information on your controller and the sorts of 'actual' numbers for the supply when you get it. Even then it remains non trivial so generally my understanding is of that conbination everyone just manually controls the speed.

[BeBuLamar]

I don't know but most of the motor drive would take the speed command as 0-10VDC. So if your controller can output a 0-10V signal you can control the speed.

[gamalot]

I did something similar a year ago. I disassembled my 48V SMPS so that I could draw the circuit diagram related to the output voltage adjustment, and then I made a PWM voltage generator to replace the external potentiometer. The output of the PWM should match the voltage range of the middle tap of the original potentiometer.

[beanflying]

Now it's not 1am and I have had a coffee. Have a good look at this and now I have had a relisten it was more an mains isolation issue than a voltage control issue. But well worth a look from 3 minutes on.

[BeBuLamar]

I am curious that if you measure the voltage across the potentiiometer what would it be?