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4th Axis Post Processor in Wrong Location

Message 1 of 4
211 Views, 3 Replies

4th Axis Post Processor in Wrong Location



I am new to 4th axis machining and am having some weird trouble.  I have a mock set up to test my output code where I am having the spindle come down and cut a partial radius using wrap tool path.  What I expect to happen in the gcode is that the machine to drop in z to the correct location, turn my rotary axis about 220 degrees (the angle of the semicircle) then retract up z. What I am getting instead is the Z and Y making giant movements in the posted gcode (as much as 20 inches in some cases).  Which doesn't make any sense because the diameter of the semicircle is only 2 inches.   The rotary is spinning around X.


What I believe is happening is that the post processor doesn't think that the part is placed at the center of rotation of the rotary axis.  But the problem with this is that I have the machine set up correctly in machine builder, and I have set the table point attachment in the setup, and I have watched the simulation with machine and all these things suggest that the center of rotation is set up with the WCS.  So I am at a loss. 

Message 2 of 4

Hi.  Are you able to attach your file?  If so, it may be easier to help.

Message 3 of 4

The problem most people run into with machine builder is not placing the rotary center on the model origin

You can see in this example in the below image that the rotary center is a long way away from the model origin and also the x and y axes are around the wrong way.


This ends up putting offsets in the rotary location in the kinematics of the machine configuration and you end up with incorrect motion like you describe



This is only a problem on machine simulation models that don't use TCP,  but you really should always place the rotary centers at the model origin

Message 4 of 4

I very much appreciate your help, I was able to get that working via your suggestion. I moved the machine inside of machine builder to the center using the offsets under Advanced Settings as reference. 


After doing this though I realized I needed to adjust my stock as that was still giving me some issues (the center of my arch was not in the center of my stock). By doing this I realized I was able to simply set the rotary axis to TCP mode and get the same output.  But this way is better, as it does not give me issues with rotary axis being ever so slightly off of the rotation axis. 

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