It is weird.  It first happened in the middle of a program.  Instead of going -Y it went +Y.  I was watching it so I stopped it.  The problem continued in jog mode.  No matter which arrow (up or down) I hit the Y would only increment, never decrement (on screen and on the mill).  At times it would get confused and loose steps (as if you were changing directions too quickly).

If you just exit Mach and come back the problem will persist (yes, in jog mode).  If you reboot the computer a few times eventually it will recover and you are able to reference the mill and zero the tool, but then it may go crazy again in the middle of the g-code execution.

I think/hope it is just my XP/Mach3 install that went bad...

Have you ever run into this?

I figure I would rebuild the machine and install the latest version of Mach3.

What files do you back up and copy back to the Mach folder so that you do not loose your settings?  I suppose there is a license file some place and some configuration files... *confused*

Any advice?

Thanks!

I have heard of this issue with some of the hacked versions of Mach, another possibility could be  bad wiring on the Direction signal for that axis, sometimes it makes others it doesnt.
Hood

Phase,

I agree with Hood - I think you have a problem with the driver recognition of the direction signal for your Y Axis. Perhaps a thorough check of your connections PC to BoB to Drivers etc may reveal the problem.

Tweakie.

Stepper motors can turn the wrong direction when one lead to one coil is broken. The motor will also run very rough.

Hi guys.  Thank you very much!

Phase,

I agree with Hood - I think you have a problem with the driver recognition of the direction signal for your Y Axis. Perhaps a thorough check of your connections PC to BoB to Drivers etc may reveal the problem.

Tweakie.

Stepper motors can turn the wrong direction when one lead to one coil is broken. The motor will also run very rough.

It seems that the first step is to check the connections of the Y-axis and the LPT cable.  It kind of makes sense that it would recover randomly and then lose it again once the vibrations of the cutting start.  However, it does not quite jive with my recollection that the Mach display and the table both only increment.  You would expect the Mach display to increment and decrement correctly (independently) if the problem is down the line from the software... but I could be remembering it wrong so it is worth a shot

I have heard of this issue with some of the hacked versions of Mach, another possibility could be  bad wiring on the Direction signal for that axis, sometimes it makes others it doesnt.
Hood

That could be also a factor.  I have the licensed software, but it is a version that is now a couple of years old.  Weird that it would have worked fine for a while and then crap up though.  If the checking of the cables does not work I'll reapply the XP optimization (in case things somehow changed).

It that does not work then I'll swap in a new hard drive and rebuild the system installing the newest version of Mach.  The pain with that is all the configuration and also that I have applied a path to zero the tool and  I'm not even sure where I got it from

Today I'm swamped working on taxes.  Will post an update tomorrow or Thursday as I get some time to work on it.

Thanks!!!

You can save the xml and other files such as tool tables, macros etc and place them into the the new installs folder and that will save your config etc.
I missed the bit about the DROs actually showing the reversal so as you say its unlikely that its a broken wire. Sounds like you may have the problem that TP had and I think his only recourse was to delete and reinstall Mach but I have not heard him mention it happen recently so possibly Brian has caught the bug and fixed it in the later versions so well worth a try.
Hood

I have rebuilt the PC -- this is something I wanted to do anyway.  The old install, when mach started it would reboot the PC over half the times.  So the reboot problem is fixed, but that did not solve the "running backwards" problem.

I was wrong on the mach DRO always incrementing.  It increments and decrements while the machine always run in the same direction. The next step is to take the electronics apart and check the connections.  Oh well... small steps...

Yes!!!

Jeff Birt scores!

It was a loose wire :-)

Thank you very much for the help. I'm rather happy now cuz not only the mill is working, but... I got a stable Mach3 installation out of rebuilding the PC -- something I duly dreaded as between the XP endless updates and figuring out where the bits and pieces are/go it takes a whole day.  But all is in the past now and it is all working :-)

Good you are sorted

The randomly going backwards stepper motor is truly a bizarre thing the first time you see it. Glad you found the problem.