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losing zero point
« on: April 18, 2010, 08:26:44 PM »
Hi all,

I'm new to mach 3 and am having a problem I can't seem to solve. I'm running R2.63 with a Taig DSLS 3000. I'm using a fairly long program and I find that after the machine runs for between 30 and 60 minutes, the z-axis will be significantly off. The zero point for this axis might be .050" (or more) higher than where it should be. I've tried resetting to zero many times and just can't seem to get the machine to remember where zero is. This machine is equipped with encoders that will cause mach to stop if something binds but there is NO binding. The software just seems to lose where it is for no reason. Any help would be greatly appreciated.

Thanks
Re: losing zero point
« Reply #1 on: April 18, 2010, 09:26:07 PM »
I just spent the weekend setting my machine up and have a problem like yours.  I tune all my X, Y and Z spot on to 1 inch each and for no reason I can find the will go back to about .020 when I call for 1 inch.  I have had to re-zero 3 times in the first day of running anything CNC and know I am missing something.  I can not wait to here what others say about this.  I have been through past post and have not come up with anything yet.

I am running a Sherline 2000 with a Latex 4 driver and of course Mach 3

Offline Hood

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Re: losing zero point
« Reply #2 on: April 19, 2010, 02:17:47 AM »
Sounds like you both may be losing steps.

lilgreg46
Have you got Sherline mode enabled?

spiltrap
How do your encoders connect and are they showing things being exactly correct.

Hood
Re: losing zero point
« Reply #3 on: April 19, 2010, 02:48:00 AM »
Hi hood,

Thanks for helping. I'm not exactly sure how to answer the question about how the encoders connect but will try my best. The motor driver has a DB-25  that's used to connect to the encoders from all the motors and there's another DB-25 that's used to connect from the motor driver to the parallel port of a PC. The only indication that I get with respect to the possibility that the encoders are working correctly is that MACH 3 doesn't quit running. If there's a bind and the stepper gets, MACH 3 will quit running and then the reset button (I'm talking about the reset button in the MACH 3 software) needs to be pressed. When I encounter this problem with the z-axis, the machine is running as if there's nothing wrong so this tells me that the encoders are where they expect to be. I hope I've described this well.

Offline Hood

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Re: losing zero point
« Reply #4 on: April 19, 2010, 03:05:43 AM »
Sounds like your encoders dont go back to Mach for monitoring purposes?
Do you have a wiring diagram or a link to such?

Hood
Re: losing zero point
« Reply #5 on: April 19, 2010, 03:35:15 AM »
Unfortunately, I don't have a wiring diagram. I went to website at the following link but didn't find a wiring diagram there either.

http://microproto.com/driver.htm

Is there something I can do to help troubleshoot the problem?

Offline Hood

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Re: losing zero point
« Reply #6 on: April 19, 2010, 03:42:29 AM »
Not much info there but I would guess the way the encoder is working is that the drive looks at the pulses received from the computer and puts them out to the motors and at the same time monitors the encoders to make sure they have turned the same amount as the motor has been told to.
 If that is the case then possibly it could be the step signals not being seen properly by the drives, try increasing the Pulse Width and Dir Prechange (on motor tuning page) and see if it helps. Might even be worth trying Sherline mode (Ports and Pins main page)

Hood