Milling HDPE

Mostly Printed CNC - MPCNC Advice
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I have been tasked with making some patches for my son’s organization. They want “soft” rubber instead of cloth. I searched around and found a suitable silicone rubber form Smooth-On. Now I need to make a mold. I was considering HDPE, because the release would be much easier than say MDF treated to seal the pores. The patch will be approx 3 in dia, and does have some small detail. The new laser I have would be great, if you could laser MDPE, but no, unless someone has a suggestion for other material.
So my question is what kind of settings speed and feed am I looking for? Most likely will use a 1/16 endmill. Depth of cut is 1 to 1.5 mm deep.

Any input is appreciated

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Should be pretty easy to cut. Single flute for sure, at 1mm DOC you should be able to go pretty fast to prevent the melting. I’d say leave a little bit of material all around for a slower finish pass with a low stepover to make it as smooth as possible. That silicone will pick up EVERY detail. Is this thing to be 2.5D or a full on 3D carve?

I made an epoxy mold from silicone using a buck i cut on the cnc a few years ago. Cut it from wood and sealed it with polyurethane. Worked out great, but did require some sanding of the polyurethane a few coats.

Good luck, and please post back how the hdpe turns out.

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