First Proper CNC Router

[Doddy]

A lot depends on the stepper drivers - many max out around 100kHz-200kHz.

My recent tinkering are with a lathe conversion and I'm settled at 8x, though I'm re-using modified drivers that will take 250kHz

[diycnc]

A lot depends on the stepper drivers - many max out around 100kHz-200kHz.

These drives are rated to 200khz. Assuming I'm running at max for 5m/min, I could get to 32x with a very healthy margin of safety.

[JAZZCNC]

These drives are rated to 200khz. Assuming I'm running at max for 5m/min, I could get to 32x with a very healthy margin of safety.

Pointless because your motors cannot resolve that low and it just stresses the pulse engine, Also if I'm reading correctly and you are using an Arduino then I'm not sure it can output pulses at this rating.? . . . But i don't know much about them so could be wrong.

The main reason to up the MS is to give smoother running motor but there is, as always a cost, much past 16x is waste and just stresses out the controller and wastes torque.

[diycnc]

The max frequency for a GRBL on an arduino is 30kHz, which effectively limits me to 1/8 anyway.

I just tried running a motor off the machine, with zero load, and it's 50:50 if it will run at 900rpm, which is only equivalent to 4.5m/min. I can feel the motor start to vibrate as it accelerates up to speed.

Going to try tidying up the wiring to see if that helps. Got twisted pair for the control side. For the motor side, this might be a silly question, should I run all 8 wires all the way to the driver and connect the pairs there, or join the pairs close to the motor and just run 4 wires from there. For the purpose of testing I'm not using shielded cables at the moment, would that impact motor performance at all?

[Doddy]

Going to try tidying up the wiring to see if that helps. Got twisted pair for the control side. For the motor side, this might be a silly question, should I run all 8 wires all the way to the driver and connect the pairs there, or join the pairs close to the motor and just run 4 wires from there. For the purpose of testing I'm not using shielded cables at the moment, would that impact motor performance at all?

I'm assuming you mean you have 8-wire steppers? In which case it depends on how you're wiring them. If in series then definitely wire the phases together at the motor - you'll reduce your losses due to the resistance of the wiring that way. If in parallel then its less obvious to me (5:30am in the morning for me) - paralleling at the motor and only taking half of the cables back to the driver suggests greater losses in the motor leads. Ideally short the motor pairs at the motor without cutting the cables and take the pairs back to the driver and terminate there as well (i.e. run the cables in parallel back to the driver). Or just wire in parallel at the motor and use wire with a large CSA to export the motor drive back to the driver. It will make some marginal difference.

Shielding will not affect motor performance, thought it might help to avoid any induced noise into signal cables.