Cutting issues

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Cutting issues

Postby Peter Stenabaugh » Wed Nov 01, 2006 5:32 am

I have been working on a small Vcarve project tonight, trying to cut out a snowflake pattern in both Lexan and in Oak. I have attached the .crv file if anyone wants to try it out.

My problem is that I am not able to obtain a clean cut in either material. I am using a speed ranging from 8000 rpm to about 12000 rpm with the Lexan, with a 90 degree Vbit - almost new and still pretty sharp. My feed rate is 20 ipm, the fastest that I can currently run the router without stepper motor skipping.

The Lexan cuts not too badly on the outer cuts (the groove and the outer chamfer - didnt do the final cutout, but on the smaller detail I had problems with material build up on the cutter, and some material build up in the cuts. The cutter did not seem to be melting the material, although this was sort of what the ugly stuff in the finer cuts seemed to be. When I got build up on the cutter, it would some times fling off but mostly I would have to wait until it was up out of the cut, stop it and clean it off, and proceed. At anyrate, the final result was pretty ugly. I even tried cutting using a light spray of WD-40, as I usually do when machining aluminum (which works really well). The WD40 did help somewhat with the build up on the cutter, but it was not the answer I needed. I dont know if the answer is a higher feed rate (which I can't do right now) or not.

So I proceeded to try the oak, which I have cut before, but with a 60 degree Vbit and with good success. I had similar results, in that the oak did not cut cleanly in the finer detail. Deeper and heavier cuts were ok, but not the fine stuff, so it ended up looking pretty ugly also.

I tried the oak at 2 different speeds, one about 15000 rpm and the other at full speed of 24000, but the results were basically the same, not a clean cut in the fine detail. I dont thing the issue is with cutter sharpness, as I had honed up this cutter after the lexan process just in case, and it seems pretty sharp, although this could also be the problem.

Ultimately my question is, has anyone had similar experiences, and if so what did you do to solve the problem - if you were able to.

I still cant seem to find the magic ratio of speed and feed for lexan at this point. Once I finish my milling machine conversion, I will be able to work some numbers, as I will have higher feed rates available, and lower cutter speeds, right down to less than 100 rpm, so eventually I will find the sweet spot on the mill, in the meantime, the cnc router is giving me a hard time.

I would appreciate everyone's input that might be able to help me out.

Thanks all,

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Peter Stenabaugh
Vectric Craftsman
Posts: 189
Joined: Wed Jun 07, 2006 7:26 pm
Location: Calgary, Alberta Canada

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