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5 axis rotaional backlash in Postbuilder

Genius
Genius

I'd like to add a small rotational move to our A axis for every A (positioning) move to remove some of the machine backlash.  What would work for me is to simply move the A axis additional 5 degress and then move it back to the target position.

 

This would be done in the Postbuilder on one of my posts only.  I do not really worry about not seeing this move in my verification, etc.

 

What would be the best solution to do this?  Should I simply catch the A value when it changes, add 5 degrees to it and then output another A move after that with the A -5 degrees?

It's kind of quick and dirty but I think it would work?

Or is there a better way of doing it?

 

Thanks for suggestions,

Jerry M.

NX8.5.2

 

3 REPLIES

Re: 5 axis rotaional backlash in Postbuilder

Gears Esteemed Contributor Gears Esteemed Contributor
Gears Esteemed Contributor

That would work, probably how I would do it.  There no G code for uni-positioning (or it doesn't do the A axis)?

I'm assuming A changes only on rapid moves (not while cutting)?  (i.e. do you ever do 4 axis contouring?)   So you need to check only rapid moves & drill cycles (not linear moves).

 

Make sure for drill cycles you check both cases (with and without "Avoid" motion between the holes) - without avoid you might have to do a G80/A(too far)/A(correct)/G8x cycle

 

Ken

Ken Akerboom Sr CAx Systems Engr, Moog, Inc.
Production: NX10.0.3.5 MP16/TC11.2
I'd rather be e-steamed than e-diseaseled


Re: 5 axis rotaional backlash in Postbuilder

Phenom
Phenom

I would create a block for A axis monitoring - maybe

 

get_A_axis

 

then issue a do template to see if A changes:

 

set tmpflg [MOM_do_template get_A_axis CREATE]

 

Then if info exists and not "" - A needs to change. Then return 1 in conditional code for a couple following blocks and if you have say [expr $mom_out_angle_pos(1)-1] (will change modal A word - so will be output) and $mom_out_angle_pos(1) (will change modal A word so put out.)

NX10.03
Windows 7 Pro

Re: 5 axis rotaional backlash in Postbuilder

Gears Esteemed Contributor Gears Esteemed Contributor
Gears Esteemed Contributor

Just thought of another case you might want to check...

 

After tool change, do you force the A out?

Do you want to be able to restart the program "safely" at any tool change (or other places)?

Then even if A doesn't change, you'll have to set a flag to re-do the A uni-position output.

 

i.e.

(end of previous operation)
G0 A30
N10 (OPERATION 2)
T2 M6
T3
G54
(you would want a "G0 A25" or "G0 A35" here)
G0 X1.23 Y2.34 A30 B40
G43 Z3.45 H2

 

Ken Akerboom Sr CAx Systems Engr, Moog, Inc.
Production: NX10.0.3.5 MP16/TC11.2
I'd rather be e-steamed than e-diseaseled


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