Reclaiming Polyethylene Pipe

Getting back to this. I've been dealing with two issues. The first is voids formed by trapped air and the second is unequal shrinkage on cooling. Stacking the pipe segments in different arrangements to reduce trapped air causes different results. The worst resulted in this, with the bottom as bad as the top.

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It would require over .200 removal on each side to get cleanup. The best result is achieved with parallel stacks of nested segments with the concave surface up. After it was fully melted, I pressed it with a s/s plate in the arbor press to get it flat, and let it cool.

Speaking of cleanup, I have a small mountain of chips from milling the plates flat, so I decided to recycle them.
Fill the pan with chips, heat about 15 minutes, press with a plate on top in the arbor press and repeat.
This seems to make a very consistent plate with no voids.
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Having grown bored with making the plates (and cleaning up the mess), I decided to make something from the material.
With nothing to stop it, the tommy bar on my arbor press falls out on the floor all too often, so it was time to make some end caps for it.
I used a hole saw to cut out some rounds then turned them on an all-thread mandrel on the lathe. The stuff machines well and leaves a good finish, even with carbide inserts.

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I've learned a few lessons so far. First, no matter how clean you think the vacuum is and how clean the chips are, there are little bits of metal etc. that show up when you fly-cut the surfaces. Second, after trying multiple different ways of cutting the pipe and laying it in the pan, the best method seems to be the simplest.

1. Cut the pipe to a length that will just fit in the pan
2. line the pan with foil and spray with silicone spray
3. lay the pipe pieces in to fill the pan with a second layer on top
4. heat @375° F. until fully softened and melting
5. roll from the center outward to the ends with a piece of teflon round to force the air out and force the PE out to the edges of the pan
6. press with a plate on top in the arbor press forcing PE into the corners and leveling the top
7. add another layer of pipe
8. repeat steps 4-6
9. Place plate on top and clamp firmly
10. allow to cool

I still get some small voids, but it is much better than before. Here are two 3/4" plates and one 1".

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R8 collet rack made from 100% recycled PE. It will mount on the right side of the "nod knuckle" on my Kent mill. This was made from one of my earliest plates, some voids visible and more that aren't.

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Great thread, thanks for all the info!

Didn't Dave (@mmcmdl ) have cans of mold release spray he was sharing cheap?

Let me search.......

Brian
 
I think that your idea of repurposing that poly-pipe is awesome, especially with the recycling situation these days. So, I did a bit of tinkering myself, and melting PE in a toaster oven can be a bit tricky. It tends to get all uneven and weird.
 
Aworoeuw said:
I think that your idea of repurposing that poly-pipe is awesome, especially with the recycling situation these days. So, I did a bit of tinkering myself, and melting PE in a toaster oven can be a bit tricky. It tends to get all uneven and weird.
Click to expand...
It tends to get all uneven and weird. You could try a heat gun; it might help melt it more evenly. Plus, some experimentation might lead to better results. And if you're still curious about this or need more advice, I've got a suggestion. Check out this polyester chip supplier I found. They know their stuff. Here's the link: https://wkaiglobal.com/. They could probably shed some light on your DIY project.
 
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