Dynamic milling issues

[Tim Johnson]

I have an offset banjo shape part. If I have the part in the center of my material The dynamic milling path only clears off about half of the last segment. If I shift the part inside the material .050" it will clear out all the material. Has anyone seen this before?

[peon]

Yes, I have seen that when facing flats. It will almost always leave an island in the center. I haven't played with it long enough to solve the issue since it was quicker to just use the 2d pocket toolpath.

[Leigh @ Kodiak]

Are you able to post a screenshot of the two scenarios you described?

[peon]

The following screenshot is a sample of 2d dynamic milling facing the top of the island leaving a cusp. I see this often. The cutter is a 1/2" bull with 1/16" CR. with a 45% (.225") stepover.

 

[The_Evil_Machinist]

Increase engagement, open back radius. That's what works for me.

[BenK]

Peon,

Try changing your step over to .1875 or less. .1875 is your tool radius - your CR (.25-.0625=.1875)

[Tim Johnson]

The internet Nazis have Photobucket blocked here along with a bunch of other stuff. I can't even see the screenshot I played with the back radius but not the engagement. I'll give that a shot.

[Goldorak]

peon, the problem is that dynimic mill don't calculate the corner radius of the tool , thats why it leave this.

[Tim Johnson]

We'll I moved it back to the original location and regenerated the path and now it's working. I flopped it back and forth three times before posting this thread. The only difference is that I've added operations after the shift.

[peon]

I changed the stepover to .125" with the same result on both dynamic mill and facing using the dynamic option.

 

Evil, I can't locate the settings you are talking about.

 

Gold, are you saying dynamic would not work in a facing application with a bullnose cutter when the tool approaches the center of the part?

 

Tim, I can email ya the screenshot if you would like.

[BenK]

Peon,

What do you have your toolpath radius set to? Try putting .125 in there. I just tried it and it seemed to work.

[peon]

I have it set at .100". But I tried a range of 0.000 to .5 and it still left a cusp.

[BenK]

That’s odd I just drew something similar to the shape you have and by adding the .125 to the toolpath radius and my step over at .1875 it took that out. Sorry I couldn’t be more help.

[peon]

Benk. Did you use a bull nose cutter or flat endmill? The flat endmill works just fine, it's the bullnose that doesn't seem to work.

[BenK]

I’m using the same .5 E.M. with a 1/16 CR.

[peon]

Hmm, that's odd. I have seen this problem since the begining of dynamic facing, therefore I avoided using it.

[peon]

Well, I'll be damned. I re-entered Ben's settings in the dynamic mill path and it worked. But.....stepping over at only .1875" is a lot of wasted cutting motion in a facing application. I should be able to step over at .375" to clean up the surface. And... it still leaves a cusp in the facing toolpath using the dynamic option. Like I said earlier, it's not a show stopper. I have just found other ways to deal with it, but why isn't it working?