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1

FAQs / A-axis orientation without Homing

« on: June 28, 2021, 12:51:13 PM »

Hello Technicians,

How can i control the A-axis orientation without Homing?

In Mach3 I have a problem with the alignment of my 4th Axis spinning my work piece around X.
I do not have a home switch on this axis and it is homed in place automatically when XYZ have homed.
The problem is that the top view of the tool path display is not perpendicular to the XY plane even when I enter 0° in the A-axis DRO.
When i rotate the display so it is approximately in the YZ plane I can see an angle of about 5° between the Z moves and lines indicating the table display Z.
When i switched to machine coordinates the A-DRO showed 355° but i read you can not change a machine coordinate.
When i set the work DRO to 355° the Z Moves do line up, but my program starts in A0 position so that is incorrect.
The first A-word does not appears before line 1300 and it also happens with programs not using the A-axis at all so it is not my program.
When i disable the A-axis the Z moves do line up, but that does not work when i want to use it.
I rotated the A-axis physically to 355 and then set this to 0 (which is something you normally do not want to do if you already lined up a part or fixation)
The Z moves lined up after regenerating the tool path display. Not the way you want, but problem solved, i thought.
Work and machine DRO both show 0 and fixating offsets all show A0.
I saved the fixations, Shut down mach 3, Clicked Yes again on the question to save fixtures an then restarted Mach3.
I Homed, Loaded my program again, DRO's work and machine show 0, A-axis did not move, all as it should be, except again the Z moves do not line up with the table display.
Again i need to enter 355 in the A-axis DRO to make the z moves line up, and this is where i run into a dead end.

When the machine coordinates show 0, all offsets show 0, and the working DRO show 0 and these are saved, where does this 5° that i just eliminated come from?
How do I make A0 the top and keep this the top even when the machine is turned off?
My program will need to run more than one day so i must be able to continue where i left. It worked in the past, but since a while i have this misalignment.
I didn't bother because i did not use the 4th axis, but now i need it again.

Best regards,

David

2

General Mach Discussion / 4th Axis move after feed hold

« on: October 21, 2010, 05:19:40 AM »

Has anyone encountered the same problem and know how to solve it?
I have a mill with a 4th axis. Normally i do not use this A-axis so normally "A" does not appear in my programs.
However, when I'm running a program and press the feed hold button, the A axis starts rotating as soon as i press cycle start.

I did a small test in which the i made a program flattening program with only a G01 command and the X and Y coord.
As soon as i pressed feed hold the axis stop moving as they should, but after cycle start the A-axis revolves 180°.
After every feed hold it rotates 180° further. The speed of the programmed X and Y movement is at that moment reduced to match the speed of the A-axis,
so the X,Y move that was being performed when feed hold was pressed are finished at the same moment as the A-axis completes this 180° move.
After that the X,Y moves continue on normal speed again and the A-axis stops as if nothing happened, until i press feedhold again.
It does not happen after stop start jog or what so ever, only after a feed hold.

Problem is that i now want to start using this 4th axis and that i sometimes need to place a workpeace next to the 4th axis even when i don't use it.
This means i can not use the feed hold button or the part will become scrap metal or the axis will hit the workpeace.

If anyone has an idea what causes this problem....

Regards
David