Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: jramurray on September 02, 2019, 06:04:54 PM

Title: On a 'GoToZero', Z axis does not stop at DRO zero
Post by: jramurray on September 02, 2019, 06:04:54 PM

Newbie user.  CNC router. Mach3.  Machine coordinates zero no problem using limit switches. I move the cutter to a new position touching workpiece.  Deselect machine coords, set  the DRO for each axis to zero.  Move away from this new reference position.  Press GoTo Zero.  X and Y return just fine, but Z does not stop when DRO Z gets to zero, but carries on crashing into workpiece.  Why do X and Y stop on zero OK, but Z sail right through ?

Title: Go To Zero behaviour
Post by: jramurray on September 06, 2019, 04:15:26 PM

Newbie, Chinese router  6040, Purchased Mach3 licence John Murray

I run the following code and it is fine.

(Go to middle of table, touch down, stop);
G90 G21 G54 G80;
G00 X200.0 Y200.0 ;
G00 Z-20.0;
M30;


With the tip at this point, I turn off machine coordinates, zero the work coordinates

Now, I move the tip to some other place using the pendant, then I run:

(Return to zero);
G00 X0.0 Y0.0;
G00 Z0;
G30;

This works just fine, the tip goes right back to zero on all axes every time.

However, if instead of running that last piece of code, I press
the Go To Zero button, the spindle immediately climbs to the top
of the Z axis and trips the limit switch.  The machine is now locked, and the only way to get back control is to wind the Z axis off the limit switch by hand.

Can you suggest a reason why this might be?  Could I have a setting wrong in the configuration?

Best regards

John Murray
jramurray@gmail.com
07599 800033

Title: Re: Go To Zero behaviour
Post by: Tweakie.CNC on September 07, 2019, 01:21:59 AM

Check you Safe Z setting (Config / Safe Z).

Tweakie.