Electronics for New Machine + Chinese Spindle + VFD

[mturneruk]

I was thinking slipping couplings. My ball screws don't have any flats on them so they are effectively only held by the tightness of 2 M4 screws in the coupling, where as the steppers do i think.

I would of thought if it had slipped, it would of been one side or the other rather than both Y and A.

As you say - I will mark and see what happens.. Do you think my 1500mm per min feedrate / 4mm depth cut was fairly conservative with a 6mm cutter ?
My cutter is only a straight two flute and it was screaming a little. Might be time to invest in some better cutters.

I read compression bit for plywood and cut the whole 18mm at once! Sounds like that might cause me a problem.

Cheers
Martin

[JAZZCNC]

I would of thought if it had slipped, it would of been one side or the other rather than both Y and A.

But are you sure it both screws lost position together.! Did you check.? After you homed the gantry would square back up so unless you checked then won't know without marks.

Do you think my 1500mm per min feedrate / 4mm depth cut was fairly conservative with a 6mm cutter ?
My cutter is only a straight two flute and it was screaming a little. Might be time to invest in some better cutters.

Unless cutter was Knackerd it should easily handle that feed rate and DOC. What RPM.?

[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.