Proper Bit and speed for cutting HDPE

[fleinbach]

I have been requested to cut multiple parts from 3/4 HDPE. I made a few test cuts and using a 1/4 up spiral bit at 2 ips at 14,000rpm and .5" depth per pass. This works fairly well but leaves a very slightly rough surface. When I use a straight bit I get a very nice smooth edge but the chip load packs very tightly eventually causing lots of vibration. I tried to reduce pass to .25" but that did not help. Before I do a lot of testing I thought maybe someone who is having success cutting HDPE could tell me how they do it.

[Brady Watson]

Frank,
Have you tried a 2-flute spiral-O? It will show a good clean edge and evacuate the chips. You might also find that making a 'chip-blower' with some soft copper tubing and an air fitting and blowing it on the bit to be a big help as well.

A single flute spiral-O might also be a good choice. Onsrud's single flute super-O is a nice tool for many plastics and AL sheet. The 52-624 is awesome for most plastics, and it is a 2-flute spiral-O. They also make a 3-flute one, but that's only used for special materials like Gator board/foam and coroplast etc. Funky stuff nothing else works on...

-B

[knight_toolworks]

that plastic tends to be hard to machine in the shavings clog and stick and jam even when cutting it on a tablesaw.

[fleinbach]

Ok, I may be losing my mind. I should have looked before I leaped. Things have been hectic here for the past month so. When I tried this cut yesterday I forgot that I had ordered an assortment of bits from Amana about 2 months ago and they where still in my office under piles of paper. Yes my office does get cluttered at times.

Well one of the bits is a spiral-O single flute made for cutting plastic. I had forgoten I purchased it until I searched the web and saw a picture of it again. That's when I remembered I had already bought one. Well as soon as I get a chance I will give it a try. I will post my results then. It won't be today I have to sheet a roof before this weather moves in tonight.

[team08]

I swear by the onsrud single o-flutes. They cut UHMW, polycab, acrylic, almost any plastic like butter. It is amazing how much the right bit makes a difference with plastic. Good luck!

[br928]

I will have to agree with Greg and Brady on the Onsrud single flute Super O bit. I had been using mine for cutting acrylic. Amazing. The past two weeks I have been using the same bit to cut 1/4" and 1/2" 6061 aluminum. I probably have thrown away 2-5 gallon buckets of aluminum chips and this bit just keeps going.