Adding a 4th axis spindle to my mill, servo troubles

[Davek0974]

Hi all,

I'm adding a spindle to my mill, just for small turning parts etc. I'm using the chinese AASD servo and drive but cannot get it to run correctly on my controller. The controller is a CS Labs IP/A unit.

It will run ok as long as speed is below say 2900 rpm but if i ask for full speed the controller faults on max following error being exceeded.

In Pid tuning you can jog the spindle at various speeds and below 2900 rpm the following error is low <100 as you go over that speed the counter just runs away until it faults and stops

JazzCNC had the same setup here...
https://youtu.be/tW8knRAOr7s

and it seems to run ok.

I also have these motors/drives on all other axes but the big difference is that they never run flat out as i have the motion tuned pretty low. I did take a motor off of another axis and connected it to this drive and it did the same thing so that points to the drive or controller??

Four pictures below of encoder channel A, at the controller, three at different speeds and one taken direct from the drive output with cable to controller disconnected.

I have no idea if these are normal or bad??

Its not a ground loop as the signal does change if i remove the shield connection.









Totally baffled.

Any suggestions?

[Davek0974]

Its not encoder related as far as i can see :(

I had a spare 600ppr encoder so wired that in and connected it by clamping in the spindle.

It still suffers the same fault, just slower as there are only 2,400 pulses instead of 10,000 per rev - the error count just goes up slower.

It still worked ok until 2980rpm.

[m_c]

What's the drives max speed, and analogue input scaling set to?

I'd guess most drives will default to 3000rpm, and 3000rpm at 10v.

[Davek0974]

Exactly that - 3000rpm, 10v.

300rpm/v

[Clive S]

Its not encoder related as far as i can see :(

I had a spare 600ppr encoder so wired that in and connected it by clamping in the spindle.

It still suffers the same fault, just slower as there are only 2,400 pulses instead of 10,000 per rev - the error count just goes up slower.

It still worked ok until 2980rpm.

I am not sure but I don't think the motors will go above 3K

[Davek0974]

Yes but i can't even reach 3k when it should??

A hand-tacho seems to think its doing 3k but the controller error says its not?

BTW, the motor and drive will do 5k but only 3k for manuf specs ;)

[m_c]

Exactly that - 3000rpm, 10v.

300rpm/v

The drive is probably not seeing the full 10v. Try bumping the rpm/v up a bit

[Davek0974]

Tried that now, apart from altering either the top speed or the acceleration ramp depending on which way i tweaked the ramp, it made no difference at all - still get the increasing error count above 2990 rpm

[Davek0974]

Ok,

Using my bench PSU it was giving 2965rpm one way and 2971rpm the other.

It was also creeping with the inputs shorted out.

I ran the auto zero speed set function which killed most of the creep.

Then adjusted the gain to 305rpm/V

It now gives 3000rpm forwards and backwards.

Did it fix the issue?

No :(

A short video of the Pid screen at 2990rpm and 3000rpm

https://youtu.be/i7GEe7jAoY4

[magicniner]

Motor slip ;-)
Most servo spindle controllers have a switch-over speed from Positional to Speed between 2000rpm & 3000rpm