Undercut Surface, Ball EM vs Lollypop in Varify

[kathy]

How do I process an undercut surface toolpath with a 'lollypop' ball endmill to give me correct path? I am processing the surfaces using parllel surfacing an a side c'plane and top t'plane, and using tool center.

When I use a ball endmill to process code, my varify (against the stl part model) looks just fine, with the shaft of the end mill cuting off the lip of my undercut. The toolpath against my outside contour is okay.

When I try to switch to a lollypop mill, to see if I clear the undercut, I get garbage tool path!

I guess, in a long and rambling way - I cannot varify using a lollypop endmill??

V8.1 (at last), Mill Level 3

Kathy

 

[Guest CNC Apps Guy 1]

You can use and Verify to Lollipop E/M's.

If you've created this tool, on the tool parameter page, you need to specify the "LOLLIPOP.MC8" file for it to Verify correctly.

Do you have the V8.1 dated January 26, 2001?

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James Meyette

[kathy]

Hi James,

I have the LP EM defined using the lollipop.mc8, and I am on v8.1 dated 1.26.2001.

Kathy

[kathy]

So, what am I missing, and what do I have to turn on/off?

I have been asked to draw a sphere on random tool path points to see it the tool is gouging or not. I would like to just run an accurate varify!

Kathy

[gmenzies]

when i have to machine undercuts . flowline is probly a better choice , also the wire frame toolpaths work well with undercuts.

just takes a little getting used to alongand accross.

i will backplot with 3 viewports and zoom to area's of concern in all three views .

could never get the lollipop to work right.

good luck

[kathy]

I used parallel surfacing instead of flowline because of the size of the code files. As it is, I had to break up the tool path into three programs. Ultimately, the parts will run on our 'new' machine, and I've already informed them that they need lots of memory in the controller.

We CMM'd the RH part (the files was uploaded on thread http://www.emastercam.com/ubb/Forum1/HTML/000680.html)along the positive 'outside' surface only. We found a surface deviation of .030 at the -y end of the part up to .090 at the most acute curvature (+y). We are now CMM'ing the center section, where the curvature (in x,y) is not drastic, to see if we see the same deviation.

Of course, I'm being questions about Mastercam's ability to produce an acceptable surface under the process. And the Lollipop / Ball EM confusion doesn't help me at all.

Thanks to All!!

Kathy

bty, at this point if I just had something set wrong it would be a relief, so I can fix it and have a good part at the end of the day!

[Toby]

Kathy,

I had a similar undercut issue that I needed to use a lollipop cutter. This is the condensed solution. Rotate the geometry so you can appraoch it from the undercut side. Establish check surfaces and create a simple flowline toolpath. Backplot and save toolpath as geometry (on another level). Now rotate all the geometry back to its original place and you can now 3d contour the center line path. You must set the tool to the center. I hope this helps.

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Toby Baughman

Magic Mfg