Location problem... Loosing location on X axis only

[HuntinDoug]

I’m having a location problems on my X axis. The problem has creeped in slowly, but continues to happen more, and more often. I’m running Artcam Pro 2008 —> MACH3 —> Gecko G540—> XZero Viper X2 with KL23H286-20-8B motors. I’ve run this setup for 4 or 5 years with no problems. I do a lot of highly detailed inlay work, so location is critical. I’m loosing location on the X axis only. It seems to be in increments of approx .024”. Most of the time when it happens, the machine is in the middle of a multiple step-down cycle. It will correctly mill a portion of the pocket, then when it returns to the safe Z to start the next stepdown, it shifts about .024” on the X axis, and continues the pocket. Where & when the problem creeps in seems completely random. If I re-run the same program, the error does not come up in the same spot, or doesn’t come up at all, so that rules out a corrupt file.

I have slowed the motor velocity in Mach3 config, but that hasn’t made any difference. Am I looking at a bad motor, or could it be something else?… Thanks

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[HuntinDoug]

Well... I think I've ruled out the theory of a bad motor. I switched it out the X axis with a brand new motor, and scrapped 2 more fretboards. I'm left thinking it has to be the G540. Anyone have any input or advice???

[ger21]

Maybe the power supply?
There are not a lot of things that can lead to an X axis error after a Z axis move.

Are you sure that it's losing position when it's lifting, and not when starting the next move?

Try changing all of the G0 rapid moves to G1 moves in the code, and see if it helps?

[HuntinDoug]

I did some more testing. It happens with both G0, and G1 moves. Here is an example... You can see in the pic what its doing. I cut the fret slots first. They are correct. Using the same .023" dia cutter, I cut an outline for block inlays that are centered between the fret slots. In the pic, the block outlines on the left are shifted about .015” to the right. The first 2 block outlines (not pictured) are correct. The block on the far right shifted about .100” back to the left in mid cycle.


The error seems to happen, and increase in frequency after the machine has run for a while. Which makes me think it may be a heat problem? I read elsewhere that overheating can cause missed steps. I'm unclear on if its overheating of the motors, or the G540 that causes the problem of missed steps. The temp of the motors in mid cycle run between 140 deg F, and 198 deg F. The G540 seems to stay fairly cool. I have a GC-01 G540 Chiller installed. I also have 3.3k Ohm resistors installed on all 3 motors.

I'm not sure how to proceed from here. I ordered heat syncs for the motors. Any other ideas???

[ger21]

If you run drivertest.exe in the Mach3 folder, do you get a flat line and steady pulse rate?

Could be a lot of things that might cause this, none of which are that easy to troubleshoot.

PC, Noise issues, drive issues, power supply, .....

[HuntinDoug]

Thanks Gerry, the input helps. I dont think its the PC. I have tried 2 XP machines, and one win 7. Tonight I'm going to disassemble the G540 and switch the internal drives on the "X" and the "A", then run tests.

[HuntinDoug]

Well... I ran drivetest.exe multiple times and got the same result each time. I ran it with all 3 cables plugged in, then less the X, then less the Y, then the Z... etc. I got the same result each time (see pic). The max variation averaged about 18. That seems like a lot to me. I also added a power conditioner hoping it may be dirty power causing the noise, but there was no change. I have a spare PC I'm going to set up and try, but my old PC had the same location problem before I upgraded. If that tests the same the only thing left is a new power supply and/or a new G540 unless I'm missing something...?

[ger21]

The pulse rate of 28500 is not ideal. It should be closer to 25000. And ideally, you don't want to see all those spikes in the graph.
But, I can't tall you for certain that this is causing the problem.

Also, Drivertest doesn't know whether or not you even have drives connected. It's telling you about the port itself and the Mach3 driver, not what's connected to it.

[KH0UJ]

Try opening your ball screw on the X axis, clean it with kerosene, then baby oil or 2T oil or any thin oil, happens to me all the time when the screw picks up a lot of saw dust, I run CNC machines on a daily basis 8 hours a day, it`s part of my monthly maintenance routine because if it happens in the middle of the job it can snap a tool bit which is a waste of material and tools. I cant imagine if any axis misses a step then the material being cut cost $700 ill be damned and fired, so every time I run expensive materials, I lube first the ball screws just to make sure it wont skip a step because if it does that means game over for me.

[HuntinDoug]

Well... I installed a brand new power supply, and a new G540. I have new shielded cables, but I havent installed them yet. The first test I ran did fine for about 90% of the cycle, then Mach3 just locked up. The g540 went into fault. I guess my next step is to change out the PC. The weird thing is, I had the original location problem with my old PC also. Any suggestions?

**EDIT** I had the carge pump switch ON on the G540. It should have been OFF. I'm re-running the same file...

[ger21]

Possibly noise related issues?

A motion controller would take the PC out of the equation.

[HuntinDoug]

I have a Smooth Stepper on the "if all else fails" list. I was thinking the ethernet ver.

[RCaffin]

Sounds more like a wiring or noise problem to me. They can be the devil.

Mach3 is quite stable for most of us. A dedicated W7 box with all 'extra' stuff turned off should be fine - it works for me. Absolutley NO internet connection!

The ethernet Smooth Stepper is definitely good. That and two Homann Designs MB-02 BoBs.

Cheers
Roger

[HuntinDoug]

Ive run 3 of the same file on maple boards with zero problems so far. So, I'm going to step out in faith and run an expensive ebony board and hope for the best. I'm thinking most of the problem was the power supply. The old one would kick the fan on and off a lot. I may put the old G540 in to test the theory. I have new shielded cables as well. Once I catch up on work that needs done, I may add a smooth stepper.

I wasnt aware an internet connection was a bad idea

Thanks for all the help guys.