Prototrak Knee Mill CNC control system upgrade

[Muzzer]

I suspect the stall torque of a 750W servo, multiplied by the belt ratio 3 could be life-threatening to the ballscrew / bearing support. I ran my system against the stops a couple of times before I installed the limits switches but luckily the machine had robust end stops which saved any damage. Personally, I wouldn't omit the limit switches, even though the soft limits may be fairly dependable. If you power up the machine and jog it before homing (if your table is miles away from the home position and you have a life to live), you may hit the stops, as the soft limits won't be set up.

I retained the 160V (SEM) brushed servo motors on my Shizuoka and they work fine with the DG4S-16035 drivers. This saved a whole lot of messing about - and money. The issue with the buzzing is presumably due to the fact we have a high resolution encoder (I forget the PPR of mine) and a brushed commutator. As the commutator has only something like 50(?) segments, it's not possible to position the rotor precisely to the satisfaction of the servo controller, given the much higher resolution of the encoder, so it hunts in vain for a precise position the best it can. I find that the buzzing only happens at certain positions but apart from the noise, it doesn't cause an issue. The actual angular movement of the motor is miniscule and pretty much lost in the backlash of the drivetrain. Certainly, it doesn't result in any movement of the table.

If you install a proper AC servo motor, it should be capable of much more precise positioning of the motor shaft, thus avoiding the buzzing noise. However, it's hardly going to improve the performance of the machine.

As for tuning the servos, this will be required whichever route you choose, brushed or brushless. Both CNCdrives and DMM Tech provide the tuning software for their systems and are easy enough to set up.

[CRM]

That is exactly what I did (modify the original 48t pulleys). I believe I posted up pictures in the build thread I referenced earlier.
I'm too far down the road of retaining the DC servos since I built a system around the ALLIN1DC board to switch to AC servos.
I just hope I can get them tuned satisfactory.

Neither the Acorn OR the Oak boards had been developed when I made the plunge with the ALLIN1DC. (although I was hearing rumors the Oak was getting close to being released)