c axis rotation on horizontal 5 axis

[maestro]

I have an aerospace part that we ar running on our Okuma MA600 horizontal with a 5th axis rotary table. This is mounted on a Technigrip dovetail fixture to run the entire part in 1 op. It has an angular flange on it that runs almost 180 degrees around it. I can machine it with 5 axis swarf just fine. My issue here is that when we run it, (I have Vericut), the machine starts out with the C axis rotary table facing the operator door, the B axis begins to rotate and right around B0, the C will rotate almost 180 degrees and the B axis will begin to rotate back towards the operator door back to basically to where it started. It seems to me that the B axis could just continue on so that at the end of the cut, it would be facing away from the operator door and the C axis would not have to make this large rotaional move right in the middle of the cut. The part looks fine the way it is. Just wondering if anyone might have any ideas. I have tryied several different toolpaths and approaches, all of which have the same result. I am starting to think this may be a post issue more than anything. Agian, the part looks fine off the machine, this question is really more for my own info than anything else. Company policy prevents me from shaing the part here.

Thanks in advance.

[crazy^millman]

Goes back to another topic put up this week about singularity. Having the part not you to Y0 Z0 in the middle of the cut will not make the post decide what is the best approach to output the code. The post does not care about your preference when it gets to way where there could be 2 possible answers to cutting the part. By not making the post get to a place where it can go 2 possible way to cut that shape you have to think far enough ahead in your tool path as to holding the part to not create this type of situation. Normal through process is follow 3 axis method when programming a 5 axis part. Hold it flat and machine away with it. Problem is on places where it can be 2 solutions and post does not really care it may or may not give you the results you want. As long as it can make the part the post for the most part is doing it's job, but when it comes to a situation like this then is comes down to not going with normal 3 axis setup for 5 axis but going with a little bit of a tilt or angle to allow the post to not have to see where it could keep going in one direction or get half way and start coming back along an axis you really did not want it to. With 4 axis work like this you would not see it, but with 5 axis where A-B, A-C, B-A, B-C, C-A or even C-B can go either way

[mkd]

yes a post controlled situation.

only two soliutions i'm aware of:

alter your part orientation (rotation about x) to favor the preferred method

play with any 'misc' values to try and bias the output. depends on the post.

if it's working dont mess......

[crazy^millman]

Draw up something similar and share that file then you can get your answer and not make someone there mad. Or you can save only a certain area of the model and share just that area you are having problems with.

 

HTH

[gcode]

this is almost certainly a post issue

try looking at the limit settings for the C axis