Machsupport Forum

Mach Discussion => FAQs => Topic started by: tfreeman on May 27, 2013, 03:14:00 PM

Title: mach3 and maxnc 15 OL
Post by: tfreeman on May 27, 2013, 03:14:00 PM

I have been using mach3 and the maxnc15 for over a year - 2D cutting with no problems.  I am beginning to experiment 3d cutting with cut3d.  My problem is - my maxnc seems to loose track of 0 height on the z axis.  All other axis' seem to be fine, but the z axis seems to go too deep after a while.  If I stop the program, and return the cutter to 0, mach3 says it is at 0, but my bit is below my original 0 surface.  It starts out fine, and cuts fine for a while, then seems like it looses track of itself.  Any suggestions?

Title: Re: mach3 and maxnc 15 OL
Post by: tfreeman on May 27, 2013, 05:16:00 PM

Changed my motor timing slightly (acceleration value so it ramped more), and changed pulse freq. from 1 micro sec to 5 micro sec - seemed to fix the issue!!! :)

Title: Re: mach3 and maxnc 15 OL
Post by: tfreeman on May 27, 2013, 05:53:07 PM

Well ----- it worked once.....  LOL :o

Title: Re: mach3 and maxnc 15 OL
Post by: tfreeman on May 27, 2013, 07:48:50 PM

OK - weight of the z-axis.  slowed the stepper down slightly and works great.  Need to build a counterbalance for the z-axis, then I can speed the feed back up.

Title: Re: mach3 and maxnc 15 OL
Post by: Tweakie.CNC on May 28, 2013, 05:26:00 AM

Hi TL,

Looks like you have successfully identified the problem and come up with a possible solution all on your own. Good work my friend.  ;)

I look forward to seeing some pictures posted of the things you make with your machine.

Tweakie.

Title: Re: mach3 and maxnc 15 OL
Post by: RICH on May 28, 2013, 07:15:15 AM

FWIW,
3D gcode has a lot of small axis moves and places a higher demand on the stepper motors.
Acceleration becomes more important because of the time available for an axis move.
The motor skips but axis movement recovers ( ie; complete loss of axis movement dosn't occur), you can't hear the skipping, yet small positional changes are happening and it is not repeatable for some specific bunch of gcode.  This is a hard one to isolate and identify what is happening.  
  
You may want to consider a higher torque rated stepper for the Z......maybe have a look at the drive setting. The counterbalance should help, but, additional margin of motor power strictly from an acceleration point of view provides for more liability.

RICH  

Title: Re: mach3 and maxnc 15 OL
Post by: tfreeman on May 28, 2013, 08:17:54 PM

Thanks guys - i appreciate the feedback.  Good suggestion on a larger stepper for z - will certainly look into it.  Thanks again!!