Going crazy with lost Z steps...

[Frunple]

Frunple...
I (we) may have been hung up on the lost steps verbiage. Can you confirm that no matter what you cannot get the machine to move negative?

If this is correct, then there may be no loss of steps, you may have a loose or broken wire on the Z axis direction pin. There could also be a bad chip on the direction circuit. This can easily be checked with an inexpensive multimeter. Disregard if only positive movement is the case.

Not sure what you mean by "no matter what"??
The axis moves in both directions fine, in fact, I've done a lot of cutting on it and had no noticeable problems with it (2D and 3D). The only time I noticed it was when I tried to cut a lithophane last week or two. That's when I saw the z axis rising, the litho was actually ramping up and the bit wasn't even touching the material by the end of it.

I'm thinking it may be the heat on the G540 based on how it cuts fine for a "while" then it starts 'ramping'. I'm assuming that may be where the heat is taking over.
Another thing I'll try is running a ground to the pc chassis as zeeway suggested. Right now I using an intel NUC as the control pc, I might go back to a regular desktop to see if it makes a difference.

[IslaWW]

Sounds like you are experiencing lost steps on the change from positive to negative motion. You are probably correct in pointing to heat with the G540. My experience is that they produce far more heat than usable power, other brands of similar products offer much more power with little heat. Keep it cool and retest.

[martin54]

Have you checked the voltage settings for your motors, don't have geckos so don't know how it is set on them but if this is only happening with rapid z axis movements then it could be a voltage problem leading to lost steps. How hot does your stepper motor get? With a lot of rapid changes in direction it should be getting reasonably hot. If it's staying cool then you probably need to up the voltage setting a bit.

Take it you have used shielded cable & only earthed it at one end, all your earths including your pc should run to one point

[Frunple]

Have you checked the voltage settings for your motors, don't have geckos so don't know how it is set on them but if this is only happening with rapid z axis movements then it could be a voltage problem leading to lost steps. How hot does your stepper motor get? With a lot of rapid changes in direction it should be getting reasonably hot. If it's staying cool then you probably need to up the voltage setting a bit.

Take it you have used shielded cable & only earthed it at one end, all your earths including your pc should run to one point

No good with the cooling... Chassis ground didn't make a difference either.

This is actually the first time I've used a Gecko and I probably know as much about it as you. The only setting I know of is a "trim" pot. The manual says it's an "audible" adjustment. I'd rather have an actual voltage reading but I don't see how with the 540. Waiting for a reply from their support.
Yes, motors getting more than warm... figure that's about right though.

All shielded connected at one end, all at the same electrical point.
I think I'm back to changing out the pc. The NUC's don't have an internal power supply, just a transformer, maybe that's the cause?? I have no idea at this point. I'll set up a new pc and give it a try.

[martin54]

How are you connected to the computer? Is it by parallel port? If it is then it could be a problem with the output voltage of the parallel port, some newer PC's & laptops had a reduced voltage on the parallel port which caused problems with mach3.

Don't know what control software your using but might be worth trying a different PC for that reason.

If the motors are getting more than just warm then the only other thing I can think of is to try reducing your acceleration & velocity settings a little to see if that helps, if its set to high then you lose holding torque & that can cause lost steps with rapid movements although I wouldn't expect them to be all in the same direction unless the moves in that direction are longer which could actually be the case as retract moves would all be positive.

[Frunple]

So the full setup is the NUC running Mach4 (big mistake I think.... but that's another story), USB to a PMDX-410, then ribbon cable (don't like this much but I have no choice) to the G540. From there, it's all this kit.
Z axis is this.
Porter Cable 7518 router with SuperPID.

I think I'll try taking the PMDX out of the control box before changing the pc, but I'm loading Mach4 on a desktop at the moment to be ready.
Already tried lowering accel and vel, literally down to a crawl, and made no difference.

[martin54]

So the full setup is the NUC running Mach4 (big mistake I think.... but that's another story), USB to a PMDX-410, then ribbon cable (don't like this much but I have no choice) to the G540. From there, it's all this kit.
Z axis is this.
Porter Cable 7518 router with SuperPID.

I think I'll try taking the PMDX out of the control box before changing the pc, but I'm loading Mach4 on a desktop at the moment to be ready.
Already tried lowering accel and vel, literally down to a crawl, and made no difference.

How you going to do that? The NUC doesn't have a parallel port & the G540 doesn't have a USB port.
Think I might be inclined to try the other desktop as well, don't know that much about NUC's though lol other than the fact that they are very small & the blurb you read says they are very powerful.
Just had a read of the PMDX 410 & I'm not sure if I like the sound of it either, see why you have no choice about the ribbon cable though. If the ribbon cable is emulating a parallel port does that mean that there are the same limitations on data transmission?

Take it you have asked questions on the mach support site, anyone else you know of running a similar set up ?

[Frunple]

USB is from NUC to PMDX, then parallel from there to G540.

The thing I really like about the NUC is literally 10 seconds to boot. It's up and ready before I lean back from pushing the power button!

I think I figured it out... Don't wanna jinx myself, was only able to run for an hour or so last night but the zero was still perfect at the end.

First thing was I tried a different pc. No change. So then I took the PMDX out of my control cabinet and it seems to have fixed it. Like I said, not enough testing yet but it's looking good.
Not sure if the ribbon was picking up interference or the card itself was but I'm guessing all axes were skipping, just never enough to notice on the other two. No where near the amount of movement on the X,Y than the amount the Z has been moving so that might be it.

I may be able to get to it tonight but if not, by the weekend for sure.

[martin54]

Haha, when you said you were taking the PDMX out the control box I thought you meant you were going to disconnect it, couldn't figure out how you would get from usb to parallel without it.
If the ribbon cable was picking up interference then I would have expected someone else to have had this issue & there be something about it on the mach support forum, having said that hopefully that's your problem & all will now be well with it.

[Frunple]

Interesting turn... Still having the same problem, did get better but never fixed. Decided to go back and try Mach3. Ran the same gcode one time and a perfect Z from start to finish!
So the problem is somewhere between Mach4 and the pmdx-410. All other cables, etc were the same.

I've said from the first time I used Mach4 that I regretted buying it.... even more so now. Riddled with issues. My advice to anyone considering it is to stay away! Don't be the beta tester that I became.

[Bit Breaker]

Mach 4 is five years over due and far from finished product with no light at the end of the tunnel. Basic CNC control like user CV settings isn't implemented yet. I don't understand ArtSoft's marketing plan or if they even have one. They seem to expect people to pay $200 for the privilege of being beta testers. Even just setting up Mach 4 is overly difficult and problematic. I recently switched over from Mach 3 to UCCNC software and their Ethernet ETH400 card connected to Gecko 540. Light years ahead of Mach 3 or 4. UCCNC customer support is great. Software is only $60.