Would anyone have recommendations for cutting a fairly long channel through HDPE with a Dovetail endmill?
Sounds like that could easily become a melted plastic disaster.
I would probably clean out a channel with a square endmill first before running a dovetail thru it. Use speeds/feeds from other discussions to calculate target chip load value for the dovetail.
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Good point. I do plan on using a regular o-flute end-mill first.
Harvey tools has a bunch of good information, here’s a blog post of theirs on dovetails: Dodging Dovetail Headaches: 7 Common Dovetail Mistakes - In The Loupe
Most of that information you probably don’t need to worry too much about though, since I’m assuming you are going to be using larger tools and you’re cutting butter HDPE.
Out of curiosity I chucked up a dovetail and ran it through some scrap HDPE on the nomad. Can confirm it’s very possible to get nice clean cuts.
Common mistakes in HDPE apply, basically don’t dwell too long or you’ll get a melted mess. There’s lots of good info on hdpe in this forum if you run into trouble.
Only other things to consider would be:
- Generating tool paths can be a pain/require careful consideration depending on your program of choice.
- Dovetails for woodworking are fine for cutting plastics just make sure you keep the manufacturers max rpm in mind.
(My dovetail is rated 18,000 rpm but I only ran it at 10,000 for the test cuts I made)
Make good chips and you shouldn’t have any heating/melting issues 
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Good points. So I did have successful chips! I was really worried that it would melt because of improper chip evacuation. However, I’m 99% certain that cutting into the material with an o-flute flat cutter first (cutting what I can) is what did the trick.
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