Curve 5-ax Axis Limits

[Travis_Buchanan]

Anyone out there have a c-axis that you have to unwind. If so do you ever use axis limits in the toolpath parameters to prevent unwinding. I have used axis limits on b axis which is z in the parameters, but only for overtravel containment. I have always been able to keep my machine from stopping, undwinding and starting again, buy changing the start point or fliping the b axis. I have now run into one that I can't prevent the unwind. How does x & y work under the axis limits tab? BTW the undwinds are produced buy the post not mcam.

[Travis_Buchanan]

I got it buy reversing the toolpath. I would still like to know how to use c-axis limits. I will experiment.

[crazy^millman]

Well I have always had unwinds and been able to get good results. I did however find that you need to look at the Z retract for getting the machine not to crash and limits not be be effected. Unwind is what you have doing 5 axis with machines and the post just takes what the ,machine can do into account when it posts code so just need to either like you say think very very far ahead to limit this or deal with it. I was also able to get very nice part using the winds and unwinds.

 

It is kind of one of those ????? without a file or some real world comparsion to look at.

[Travis_Buchanan]

Ron, we are a very high production shop. Unwinds are extra cycle time that we don't need. And once in a while I have a tool like a dove-tail or profile with larger dia at bottom that can't retract in the middle of a part and undwind. My C-axis limits are -110/+290 my post is set at -90/+270 with max delta c at 170. I think I am going to bump all the post values up 10 deg. This would help alot with overlap and still give me 10 deg buffer. I would also like to play with axis limits in the 5-ax tool paths to see where it would unwind before posting.

[steve f]

One of the customers I program for has a router with a 0-360 range on the C axis. I've yet to run into a situation where an unwind was required but that's not to say I won't in the future. I ussually just use the "think ahead" method.

 

Version X wish #4526: handle 5 axis machine dynamics and retracts internally so backplot and verify are correct. It'd make post editing a heck of a lot simpler as well!

 

steve

[cadcam]

Some machine like this have like C-axis +180 to -180 and they will call it 360 in C-axis but you need to find this part of it and say start at the postive side all ready so you can go past C-0 and go to the C-180 direction.

 

So as Ron was stateing you need to set this up ahead of time when setting up on the machine.

 

lay you part with in the limitations of the C-Axis

[wildcat99]

quote:

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I think I am going to bump all the post values up 10 deg.

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That's what I would try first. Adding a little overlap took care of a lot of unwinding problems for me.

 

I've never really used the axis limits much, but I do use the Misc Values a lot, mostly the "B-axis Pref." setting of positive or negative to keep C from unwinding.

HTH

[Travis_Buchanan]

Thanks for the replies I also use misc values to flip the b axis to try and prevent unwinds.