[pwccycles]

Greetings,

I am having a problem with a shifting x,y,z origin on my Nema 23 4x4 pro table. I turn everything on, initialize the table zeros in Mach4 and set my work origin. I will then do a cut, occasionally stopping it in the middle if I don't like what is happening which may or may not be the cause if the issue. What's happening is the x,y,z zero moves slightly. I'm not sure if it's the stepper motors getting out of sync or mach4 losing track of where the "zero" is. I noted this by moving the bit to the zero position and checking.

Has anyone else noticed this behavior? Ideas or suggestions to troubleshoot would be appreciated as I'm still learning!

Thanks!

Perry

[awerby]

It sounds like you're losing steps. This happens when stepper motors try but fail to reach a commanded position. In an open-loop stepper system, there is no feedback mechanism to compare the commanded position to the position actually achieved. But it will be evident when the tool is moved back to the original zero position - the DROs will say it's at zero, but the place will be different.

The first thing to do is to check for mechanical problems. This might be a sticky place in the slides, a slipping pulley, etc. If that's not it, then usually adjusting the velocity and acceleration settings will fix the problem - if the velocity is in a reasonable range, reduce the acceleration by half and retest; usually it will behave better. Of course, there are other things that will cause lost steps, but try these first and let us know what happened.

[GME]

Another problem could be noise. It's questionable that you would be having a sticking or slipping problem with all three axes - especially with the Avid Z-axis. Have you greased your bearing blocks and Z ball screw?

If you are using the Avid settings, they are are generally considered fairly conservative. If you are using them, I question whether the stepper settings (acceleration and velocity) would be an issue.

If you are using a VFD and spindle, I'd look there. It would be helpful if you could tell us more about your setup.

Not long ago I found a noise issue with my HY VFD. It was causing my X axis to move negative about 1/16" when cutting a long line of slots in some hold down clamps. The shift occurred on about the 4th or 5th clamp and was a single shift. My grounding and wire types were all correct. Turns out I needed an AC incoming line filter. The filter turned out to be my 'noise be gone' solution.

I used a very low tech method for identifying noise. I took an AM radio and tuned it off channel. Then, I turned on my spindle and listened for a change. The noise level when up substantially - I mean way up. I added the line filter and tried it again. When I turned the spindle on, I didn't hear an increase in the static. Problem solved. I suggest trying the AM radio trick during the day, as there seems to be less random static during daytime hours.

Gary

[mactec54]

Greetings,

I am having a problem with a shifting x,y,z origin on my Nema 23 4x4 pro table. I turn everything on, initialize the table zeros in Mach4 and set my work origin. I will then do a cut, occasionally stopping it in the middle if I don't like what is happening which may or may not be the cause if the issue. What's happening is the x,y,z zero moves slightly. I'm not sure if it's the stepper motors getting out of sync or mach4 losing track of where the "zero" is. I noted this by moving the bit to the zero position and checking.

Has anyone else noticed this behavior? Ideas or suggestions to troubleshoot would be appreciated as I'm still learning!

Thanks!

Perry

Could well be noise as GME has said, there are other factors I have been concerned with these packages, can you take a photo of the electrical Cabinets and power supply to them

[pwccycles]

Greetings,

I am having a problem with a shifting x,y,z origin on my Nema 23 4x4 pro table. I turn everything on, initialize the table zeros in Mach4 and set my work origin. I will then do a cut, occasionally stopping it in the middle if I don't like what is happening which may or may not be the cause if the issue. What's happening is the x,y,z zero moves slightly. I'm not sure if it's the stepper motors getting out of sync or mach4 losing track of where the "zero" is. I noted this by moving the bit to the zero position and checking.

Has anyone else noticed this behavior? Ideas or suggestions to troubleshoot would be appreciated as I'm still learning!

Thanks!

Perry

Thanks for the idea guys. Turns out that when I used the stop command instead of the feed hold I lost steps and the coords went out of sync.

Thanks!!!

Perry

[GME]

Thanks for the idea guys. Turns out that when I used the stop command instead of the feed hold I lost steps and the coords went out of sync.

Thanks!!!

Perry

Good news, Perry. Glad it turned out to be such a simple fix.

Gary

[nlancaster]

I should have thought of this because I have had the same damn issue. Use stop and machine stops so fast it loses steps. Feedhold, then Stop to stop a program.

[mactec54]

Thanks for the idea guys. Turns out that when I used the stop command instead of the feed hold I lost steps and the coords went out of sync.

Thanks!!!

Perry

I'm very surprised that this is your problem using Mach4 this should not be happening, this happened with Mach3 even using fee hold, I would say you have some other issues also maybe with the motor tuning

It could happen if the inertia is to great for the steppers to hold position when you do a stop then it would / could loose steps, it should not make any difference whether you use Feed hold or stop