Weiss VM32 mill conversion

[DavidR8]

I have a Weiss VM32 mill that I'm planning to convert.
I lucked into a private sale of an new Arizona CNC kit for my model of mill, new DMM servos and drivers, Masso G3 and pendant plus a bunch of other brand new kit.
Part of my planned conversion is a swap of the BLDC spindle motor to enable control of the motor via the controller interface.
The servos that I bought in the kit are DMM so I looked at a DMM 1.8 HP AC servo and driver. North of $1000 USD/$1400CDN is too expensive for my blood.

I can get a no-name AC servo and driver off eBay for about $750 CDN which is a bit more palatable but still expensive. And the sketchy documentation, tuning software is not great.

I considered an AC motor and VFD but the motors in the 1.5 HP range are heavy beasts and I'm not keen on putting that much weight on the head of my bench mill.

Ran across a lathe CNC conversion that used a 90V DC treadmill motor with a KBB driver that uses a potentiometer to control speed. The conversion I saw used a board to take a PWM signal from the CNC controller to provide input to the KBB driver board (instead of the potentiometer) allowing full control of rpm and direction of the DC motor.

KBB DC motor driver board:

eMotors Direct - Canada's Online Source for Electric Motors, Gearing, and Controls

www.emotorsdirect.ca

PWM board:

C41S-PWM Variable Speed Control Board

CNC4PC C41 - PWM Variable Speed Control Board

cnc4pc.com

In the documentation for the latter is this pdf showing the PWM board connected to an HTG control board

Does anyone see any flaws, pitfalls or caveats with this approach?

 

[DavidR8]

Yesterday was a landmark day. Managed to get movement on all axis and the servo powered spindle.
Have some binding on the X axis which is causing the servo to error out. Will need to sort that out.
Still need to design and print some proximity switch mounts and then I will be able to properly test and calibrate everything.

 

[DavidR8]

The mill made it's first chips today.
Just a surfacing cut using the MPG.
Very happy with how it all came together.
Still need to add the tool length sensor and tidy up the cable management.

 

[DavidR8]

Calibrated the X and Y axis tonight after making sure all the ball screw couplers and gibs were snug.
Backlash on the Y was .06mm and on the X was .1mm which is pretty respectable and well within the backlash compensation limits of the software.
Managed to get both X and Y to repeat to 0.00mm or .01mm in both positive and negative directions.
I call that a major win