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Z axis moves down after program ends
« on: December 14, 2013, 08:44:47 AM »
Hello all, I've been using Mach software for some time now,(Since Mach 2) but haven't really done much with setting up Mach software. So my problem is this. My Z axis moves very freely. When I reach the end of the G code program the motors shutoff and the z axis will move down which will lose my z "0". I use BobCad/Cam to generate my G & M codes. I have tried to eliminate the M30 code but it still shuts off the axis'. I'm sure it's a post processing problem but not sure how to correct it. I also would like to point out that when I choose the Mach 3 post processor in BobCad/Cam my milling machine has a few issues, like making a big looping motion before it will start the programed cut. However if I chose the Mach 2 post processor and delete the first line in the G code program, it works properly except at the end of the program when the motors shutoff and I lose my Z axis "0". One other thing I'm having an issue with is the smoothness of cutting an arc. I thought i read some where that using Mach 2 this was normal, but with Mach 3 the issue has been resolved. If so what do i need to do to make the arcs smooth instead of egg shaped. Thanks for your help!!!!

Pat

Offline Bodini

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Re: Z axis moves down after program ends
« Reply #1 on: December 14, 2013, 09:58:52 AM »
My Z axis moves very freely. When I reach the end of the G code program the motors shutoff and the z axis will move down which will lose my z "0".

Do you mean that the steppers/servos turn themselves off when it gets to M30?

That would lead me to think that you have this option selected:  Mach3> [pulldown menu] Config > General Config > Pgm End or M30 or Rewind > E-Stop the system.

If you have that box ticked, un-tick it.

Offline Hood

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Re: Z axis moves down after program ends
« Reply #2 on: December 14, 2013, 10:17:05 AM »
Regarding the "big looping motion", that is most likely the IJ mode is wrong. To solve that the best option is to have the post processor in BobCAD put the correct G90.1 or g91.1 in the initialisation string. You can also change the default setting in General Config of Mach or simply MDI it, however if you load code written for the opposite IJ mode  and  the code doesnt define which (by having a G90.1 or G91.1) then it will again be wrong and you will have to MDI or change the setting again.

Egg shaped cicles sounds like Backlash and is nothing to do with Mach.
Hood
Z axis moves down after program ends
« Reply #3 on: December 14, 2013, 12:01:44 PM »
Thanks that worked!!! Now to figure out the arcs.



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Z axis moves down after program ends
« Reply #4 on: December 14, 2013, 12:11:52 PM »
I assume to take up some backlash is to adjust my mill or do it with the mach software. Also it seems if I don't do a complete circle it arcs fine. When I do a complete circle it is always egg shaped at the north and south points on the circle.


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Offline Bodini

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Re: Z axis moves down after program ends
« Reply #5 on: December 14, 2013, 01:12:10 PM »
Show us the Goode for the problem arcs.
Z axis moves down after program ends
« Reply #6 on: December 23, 2013, 02:37:35 AM »
Well it seems the problem has taken care of itself. I will post the g code if it does it again. Thanks everyone for your help.


Pat


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