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fartman89
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Joined: 11/09/2011
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Posted: 05:13pm 24 Sep 2011

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I purchased a grizzly mini mill about 1.5 years ago and have used it primarily as a drill press in that time. I recently came into a bunch (500 lbs worth) of nice thick HDPE for free.

Here is a video of me milling it: click on piture to view video on youtube:

My questions are: What speed should I be using to mill this stuff? 2 flute or 4? and does anybody have any tips and tricks?

MacGyver

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Joined: 12/05/2009
Location: United States
Posts: 1329

Posted: 06:01am 25 Sep 2011

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fartman89

I use plastic a lot and though I haven't seen your video, the general rule is: The softer the material, the faster the quill has to spin. So, for HDPE, you're best bet is to let it rip!

If you were to get into some really hard material, like cast iron, you'd want to slow things down a bit and use a cooling lubricant, but with plastic, if you slow down, things get hot and melt! Just tear through that plastic like there's no tomorrow; that's what I do.

As to whether or not to use a 3 or 4-fluted quill, I use a 3-fluted one, because I've found the 4-fluted quills tend to capture too much debris and get hot. The three-flute ones kick out the chunks faster and like I said, heat is your enemy with this stuff.

By the way, it may be too late to change it, but your video's title says H"T"PE and it's H"D"PE in reality. It stands for high Density poly ethylene I think.

Edit: I'm back after watching the video. One thing I thought I'd mention is this: You'll find the quill will cut better in one diretion and tend to "walk" in the opposite one. Be sure your "gibs" are tight, so the setting on your feed doesn't have any place to "wander" off to or you'll be breaking quills as well as messing up cuts. The vacuum is a nice touch. I'm tending these days to use the plastic as a base and replace all "working" surfaces with either brass or steel. I build a lot of pumps and air engines and the plastic makes for a nice-looking as well as functional base material for the builds. Keep up the good work; looks like you're getting the hang of it.

. . . . . MacEdited by MacGyver 2011-09-26

Nothing difficult is ever easy!
Perhaps better stated in the words of Morgan Freeman,
"Where there is no struggle, there is no progress!"
Copeville, Texas

fartman89
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Joined: 11/09/2011
Location:
Posts: 3

Posted: 02:27pm 24 Oct 2011

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MacGyver said fartman89

I use plastic a lot and though I haven't seen your video, the general rule is: The softer the material, the faster the quill has to spin. So, for HDPE, you're best bet is to let it rip!

If you were to get into some really hard material, like cast iron, you'd want to slow things down a bit and use a cooling lubricant, but with plastic, if you slow down, things get hot and melt! Just tear through that plastic like there's no tomorrow; that's what I do.

As to whether or not to use a 3 or 4-fluted quill, I use a 3-fluted one, because I've found the 4-fluted quills tend to capture too much debris and get hot. The three-flute ones kick out the chunks faster and like I said, heat is your enemy with this stuff.

By the way, it may be too late to change it, but your video's title says H"T"PE and it's H"D"PE in reality. It stands for high Density poly ethylene I think.

Edit: I'm back after watching the video. One thing I thought I'd mention is this: You'll find the quill will cut better in one diretion and tend to "walk" in the opposite one. Be sure your "gibs" are tight, so the setting on your feed doesn't have any place to "wander" off to or you'll be breaking quills as well as messing up cuts. The vacuum is a nice touch. I'm tending these days to use the plastic as a base and replace all "working" surfaces with either brass or steel. I build a lot of pumps and air engines and the plastic makes for a nice-looking as well as functional base material for the builds. Keep up the good work; looks like you're getting the hang of it.

. . . . . Mac

Thanks for the info and I will let her rip from now on.

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