I carved this with a v-bit in HDPE. (I also entered it in the holiday contest, if you want to see a video and project details). A single pass with a 60 degree v bit. But it was kind of a mess to clean up after carving. I can’t really sand the HDPE to get rid of the fuzzies and stuff from down inside the carves. So I used tweezers to pull out all the crud that remained.
There must be a better way. Tips on getting an awesome carve with this HDPE stuff?
Looks nice and clean. I dont know if there is a simple way to get the fuzzies out of HDPE. I tried it and gave up. Tried every bit imaginable, and the only one that seemed to work is the O flute type of end mills. They have a high relief and pull out the material pretty well and dont leave much behind. Did you start with white material and then paint it before you v bitted it?
Best I could think of would be to mask over the whole thing before carving, then use a sanding/polishing mop like this pictured in your drill to get into the grooves. I have used this method with acrylic. Best of luck! 
I have spent a lot of time milling HDPE. I’ve found a 0 helix bit does best. I have not cut it since I got my Makita, but with the stock SO2 spindle, speed setting of 7-8 with a .125 or .0625 0 helix with 22-25 ipm and .0625 or .05 DOC worked well. The flat end mill makes highly detailed cuts nearly impossible (unlike the v bit), but most signage is possible. Here are some of my projects.
Tom
@ThomasSasala Thanks for that info. Out of curiosity, how deep do you have to carve to get through the top layer on those two color HDPE sheets? Is one pass at 0.05" enough?
Also, can you link me to an example of a 0 helix bit? I’m not sure I know exactly what that is.
I’ve found .05 to be enough, but it does seem to vary based on the batch of materials you get. 0.0625 is certainly more than enough when you factor in any variability of the material height and waste board.
-Tom
I’ve been getting clean cuts in HDPE using a 1/8" single flute end mill. When I was still using my 48VDC spindle, I used a feed rate of 40ipm at 10,000rpm. With my DWP611, I set it at 3 and use a feed rate of 60ipm. A 1/8" bit is small enough for the things I’ve cut but a 1/16" bit might be more suitable for a more detailed carve.
Thanks for the links. I bought a few different sizes just now. I can always use more end mills.
