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Commanding specific rotation direction with 4th axis

Utry2win

Aluminum
Joined
Aug 17, 2011
Location
Lakeland, FL
Ok, I have a sub program I am trying to run, where I would like a the part to rotate back and forth. Unfortunately, the rotary seems to only want to rotate in the positive direction. Here is a sample of my code. I have tried it with A180. and A-180. Both always continue in the positive direction on the return pass. Mori Seiki SV5020 MSG-805 control (mitsubishi).

(BEGIN SUB)
O8718
G90 G59 G1 Y1.1456 F20.
G19 G03 Y-1.1456 R1.25 A0. F500.
G01 Y-2.2456 F20.
G91 X-.03
G90 G59 Y-1.1456
G19 G02 Y1.1456 R1.25 A180. F500.
G01 Y2.2456 F20.
G91 X-.03
M99
 
Most rotary's can have a "shortest distance" parameter set, but seeing as you're going 180 there is no shortest distance, so it looks like it's reverting to its "normal" rotation. If you want it to go a certain direction in this instance, try breaking the moves containing A into two. Like two 90's or a 179 and a 1.
 
In regards to G91 incremental move, that may work, unfortunately, it is on a simultaneous 3-axis move containing absolute positions.

Parameter wise, I looked through the parameter manuals for the machine, and could not locate a default direction, or shortest direction parameter listed, although I am not dismissing this as a possibility still.
 
Just wanted to give a follow up. I ended up using all incremental moves in my sub program to get it working. Obviously this will not work for everything, but it short term solved the issue.
 








 
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