Electronics for New Machine + Chinese Spindle + VFD

[mturneruk]

Thanks Jazz. Hmmm. I hadn't homed the machine today. Also my Y / A currently only has prox sensor on one side e.g. Y. Are you saying I should have sensors on both sides e.g Y and A?
Makes sense when i think about it. Now i think i understand why Y and A decouple during homing.

I dont know if both screws lost position or not. Will measure tomorrow. I suspect there is some slippage going on on one side or the other. Would a small drop of loctite be sensible on the coupling bolts ?

RPM was around 14,000. I tried faster and slower and that sounded most comfortable.

[njhussey]

My machine started losing position, it was a loose pulley on the stepper...I hadn't put enough loctite on it!

[JAZZCNC]

Would a small drop of loctite be sensible on the coupling bolts ?

Not sensible more Essential. I'd also file a flat on the Ballscrews.

Regards Homing to separate switches then Yes you want them so can reset gantry square if start losing steps. If not then over time if you lose steps on the unswitched side it will never get reset so error builds over time and eventually racks the gantry and stalls one of the motors while other keeps going. Often this happens at high speeds when torque is lowest and you can imagine the results.!!

[mturneruk]

OK. It did it twice more this morning, and i am certain that the couplings are not at fault. I marked them and they haven't moved.
I homed the machine this morning before i started.

The first time the Y was 250mm off where it should of been when it started cutting along the x direction, and the second time I have no idea what it was doing, but basically it appeared to slow right down and then start cutting in the wrong direction. I was profile cutting 18mm lightply.
In all instances the feedrate has dropped from what i set (1500) to very slow when the problems have occurred, although Mach3 did not show this on the screen.

I have tried going back to the default Mach Screen layout as i was previously using 2010 screenset, and it still did it.

I am trying now a mid air cut, to see if i can reproduce it, and to film what actually happens without any danger.

[JAZZCNC]

You have got the steps per setting right haven't you.? Have you checked it's moving the correct distance.?

[mturneruk]

Yep. Steps per are correct. Distance is correct.

I am now suspecting that i might have a faulty UC300. A few minutes ago Mach3 was not recognising the UC300 for some reason when the USB lead was plugged in. I wiggled the lead, restarted the PC, restarted my electronics, but no connection (UC300 power light was on though). So i disconnected everything and took the lid off. Everything looks normal inside my box Checked connections etc. I did notice that the case (which is earthed) may of been touching the outside metal part of the USB connector. I fixed this and plugged the USB in again and it then connection was established ok. Not sure this is related to be honest.

So I did a mid air cut with the spindle and extraction running and that was ok. So then I tried to re-cut the part that screwed up before as a test and not only did i get a few nasty jolty noises during the cut, halfway through Mach disconnected from the UC300 and the job stopped. After that I reconnected the UC300 and tried jogging and doing another midair cut and that worked ok.

All the problems seem to happen when i am actually cutting something and not when jogging / air cuts.

Ideas i have had so far are....

1. Faulty UC300.
2. Vibration from the machine during cutting effecting the electronics somehow which are under the cutting table.
3. Noise. Surely this would effect air cuts as well though.

I have tried several USB leads all shielded and different ports on the PC and that's not the problem i don't think.
Lost at the moment. Any ideas much appreciated.

[JAZZCNC]

I did notice that the case (which is earthed) may of been touching the outside metal part of the USB connector. I fixed this and plugged the USB in again and it then connection was established ok. Not sure this is related to be honest.

Yes this would cause problems because it would create an earth loop with the PC. The USB gets it ground from the PC earth.
Don't earth the case of the PC to same Star Earth point used for the control box. The Pc gets it's earth from the Mains directly thru the plug.

Vibration or resonance won't cause these problems. It mostly makes the motors run rough and lower performance not miss steps etc unless really bad.

USB can be flaky to start with so if you have any poor wiring connections or noise going on then it will be picked up.

But Before starting on the wiring I'd go over the mechanicals with fine tooth comb to make sure no lose couplers or binding issues.

Then Go over your wire connections very carefully. Make sure Power wires are away from signals. Esp around the VFD.

Trying to diagnose problems like this is difficult from distance because it could be so many things. Often it's something really simple or silly.!!

[mturneruk]

I have just proved that it's related to load on the cutter.

I tested cutting about 3mm passes of birch ply (now scrap) while Jogging. After only a few centimetres Mach3 would stop (As i mentioned before when i was surfacing my bed).
It just did it about 10 times in both X and Y directions. Each time no error condition was present in Mach 3.

All i needed to do was to go in the other direction and then it would work in the direction which had stopped working previously (With a bit of a jolt to start).
I really don't think it was my keyboard. It'a a Steel series shit hot mechanical key thing.

Having got it to do that consistently, as soon as i rose out of the material and did the same thing, it did not stop at all.
This is consistent with my experiences so far.

Could this mean the drivers are at at fault in some way. Something to do with all those dip switches possibly ?
Overheating, protection kicking in or something?

Maybe I should of gone for those Leadshines as you suggested.

As usual. Thanks for your excellent replies Jazz. Is this your forum ?

Cheers
Martin