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Author Topic: Mach3 strange behaviour Z axis on lathe  (Read 173 times)

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Offline DMBGO

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Mach3 strange behaviour Z axis on lathe
« on: April 10, 2020, 02:30:42 AM »
Hi, it's been a while since I was here, but like a bad penny I keep turning up.
I had a problem with my Spindle on the lathe which turned out to be a faulty servo controller, so for the time being I have gone back to my VFD and 3 phase motor setup. This issue occurs regardless of the spindle running or not, also I'm using an ESS, so I doubt it's caused by interference from the VFD.
After getting the spindle working, I thought I'd give things a try and attempted to bore a 40mm wide x 25mm deep hole in a tube. The Z axis, however was unwilling to co-operate.
The problem when I run the job is as follows:
The X axis moves to the commanded position
The Z axis remains stationary, but the DROs on the computer count down as if it is moving.
Upon reaching the commanded depth (25mm) on the Z axis (but not actually moving Z) it moves back 25 mm and this time it actually moves Z, so it is actually 25mm away from the job on the Z axis.
This repeats, as it thinks it is doing cuts, so the Z axis is further and further away by 25mm a time from the job.
I am using step and direction to control the Z axis servo driver, so to test things, I commanded G0z0 when the Z axis was at 25mm. The z moved as expected. I then commanded G1f100z0 from 25mm and got no z movement, although the Z DRO showed the axis moving to 0.
I'm a bit perplexed by this behaviour and I'm hoping someone will have something for me to try.
Cheers and stay well
Dave
« Last Edit: April 10, 2020, 02:35:13 AM by DMBGO »
Cheers

David

Offline DMBGO

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Re: Mach3 strange behaviour Z axis on lathe
« Reply #1 on: April 10, 2020, 02:42:14 AM »
Just a quick update, I've just tested the X axis the same way as the Z axis, and it only moves in the positive direction as well. It's as if  the axis are both missing a G1 command in the decreasing direction. I'd immeditaley look at the wiring, but I don't see how G0 could work and not G1.
Cheers

David

Offline DMBGO

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Re: Mach3 strange behaviour Z axis on lathe
« Reply #2 on: April 10, 2020, 10:05:45 PM »
A further update to the issue, in the cold hard light of the next day. After a bit more fault finding, I have discovered that it is possibly a windows issue. If I start everything from"cold" (restart the lathe and restart M3) I am able to successfully run the Gcode that I posted before (G01F100Z0) and have it successfully move the axis from 100mm to 0mm. If I then run a Gcode cycle (the same boring cycle that I ran yesterday), I does not move the axis in a negative direction. After completing the cycle, It then won't obey the command (G01F100Z0) either. It will still work in a positive direction.
I am using a PC that is getting the windows insider updates, so I'm currently trying to go back to a previous build of windows to see if that fixes things.
Cheers

David

Offline DMBGO

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Re: Mach3 strange behaviour Z axis on lathe
« Reply #3 on: April 11, 2020, 05:16:46 PM »
Right, I hope this is of interest to someone else, since I rather feel that I am talking to myself here :(.
I have bought a retail version of Win10 home and found another PC. I will install Windows on that computer and restore and copy my mach3 folder onto it. This will tell me if the problem persists. If it does, it will be an expensive exercise.
Cheers

David

Offline DMBGO

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Re: Mach3 strange behaviour Z axis on lathe
« Reply #4 on: April 11, 2020, 10:23:33 PM »
It was an expensive exercise, but I did fix it in the end. Thanks for all the helpful and corcerned replies. :)
I must admit that due to the lack of support I did consider not posting the final solution here, to what, after all is a strange problem.
In case someone comes across this issue, this is what fixed it:
As stated previously I setup a new installation on a different PC using W10 Home edition. I reinstalled the recommended version of M3 from the Warp9 website, however the issue previously described persisted.
I then hit upon the idea of running the commands that were generated by mach in the window showing the TAP file, one at a time, and testing the issue after each command. This enabled me to see where in the sequence the issue was introduced.
I discovered that after the M3 command to turn the spindle on, the axis would then only obey the G1 command in an increasing direction. Example G1F100Z100 - works G1F100Z0 doesn't work, although M3 on the computer behaves as if it is working.
I then disabled the spindle in M3 and restarted M3 (this last is important), the GCode TAP file was then able to be run.
Cheers

David

Offline Tweakie.CNC

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Re: Mach3 strange behaviour Z axis on lathe
« Reply #5 on: April 17, 2020, 01:13:35 AM »
Quote
I discovered that after the M3 command to turn the spindle on, the axis would then only obey the G1 command in an increasing direction. Example G1F100Z100 - works G1F100Z0 doesn't work, although M3 on the computer behaves as if it is working.
I then disabled the spindle in M3 and restarted M3 (this last is important), the GCode TAP file was then able to be run.

Hi David,

I'm getting a little confused here between the terms. Could you please re-phrase using 'Mach3' and 'M3'. Many thanks.

Thanks also for taking the time to explain your solution, I appreciate it would perhaps be a guess but do you think the M3 problem lies with Mach3 or the ESS ?

Tweakie.
KEEP SAFE !

Offline DMBGO

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Re: Mach3 strange behaviour Z axis on lathe
« Reply #6 on: April 17, 2020, 05:43:50 PM »
Hi Tweakie, you can substitute M3 throughout my post, with Mach3, I was just too lazy to type it :).
It would certainly be a guess, but I suspect that the problem was caused by the ESS plugin. I could have disabled the ESS plugin, but I would have needed to setup a parallel port then to see if I was right. I also suspect there is more to it, because I have successfully run both the ESS and the VFD spindle, using the PP on the Ess to turn the spindle on and off, as well as to control the VFD spindle speed (with 0 - 10V) previously.
Cheers

David

Offline Tweakie.CNC

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Re: Mach3 strange behaviour Z axis on lathe
« Reply #7 on: April 18, 2020, 01:11:37 AM »
Hi David,

The reason I mentioned this is that Mach3 is obsolescent and will not be changed in the future but the ESS is current and although Warp9 may have discontinued Mach3 support they may be persuaded to make changes to their plugin if the demand for Turn was present.

Just a thought.

Thanks for clearing up my M3 / Mach3 confusion  ;)

Tweakie.
KEEP SAFE !