Polyethylene filament?

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jferguson
Posts: 163
Joined: Mon Mar 30, 2015 7:26 pm

Polyethylene filament?

Post by jferguson » Thu Oct 20, 2016 5:35 pm

I want to print a fixture for holding parts of an assembly which will be glued together using isocyanurate glue. I can machine one of these things from HDPE which seems immune to this glue, but the design and 'making' of a print would be so much easier. It appears that while you can print with polyethylene, it is too twitchy to be useful. Can anyone think of anything else I could try which isocyanurate glue won't stick to?

Slipshine
Posts: 182
Joined: Sun Apr 13, 2014 3:02 am

Re: Polyethylene filament?

Post by Slipshine » Fri Oct 21, 2016 10:16 pm

This probably wont help much but when I am trying to see what glue wont stick to it is usually anything I am trying to glue together.

jferguson
Posts: 163
Joined: Mon Mar 30, 2015 7:26 pm

Re: Polyethylene filament?

Post by jferguson » Sat Oct 22, 2016 2:41 am

Spot on Slipshine. In fact this is how i found out that HDPE is hard to glue. I milled the parts for a dust shoe (vacuum dust sucker) for my new CNC router with the intention of glueing them together. I couldn't find anything that worked so I ended up using screws - stuff machines really nicely and if you didn't know what I'd originally intended you wouldn't think the project was a bit bungled.

I googled HDPE filament. There is a lot of discussion about turning milk bottles into filament but only a little about how difficult it is to get good prints with it. There seems to be a lot of Chinese sources but their ads don't make me confident that they know what HDPE is.

Maybe PETG would work. I guess I'll buy a roll and find out.

I've also got a cnc mill and the printer. over the last year, i'm amazed at how often I set out to make something using the mill and then think some more, modify the design a little and print it. screwing up a print design doesn't seem nearly as exciting as what can happen on the mill.

If worse comes to worst, I'll just mill a chunk of HDPE.

but i'd really hoped someone here would have had experience with printing the stuff.

ksevcik
Posts: 56
Joined: Fri Oct 21, 2016 1:07 am
Location: Houston, TX

Re: Polyethylene filament?

Post by ksevcik » Sat Oct 22, 2016 4:01 am

PETG is good stuff, but if you don't want to needlessly buy a roll, you might test your glue on some straight PET first. Most soft drink bottles are PETE (#1 in the little recycle triangle), which should be pretty similar to PETG as far as glue is concerned. Polystyrene (PS #6) should be similar to HIPS filament, though it's not quite as easy to find in a grocery store, it's more of an industrial plastic. I think many plastic filament spools are PS? At least I know one I had a while ago was. It's hard to beat HDPE for molecular slickness, though.. Maybe Acetal (Delrin)? Looks like MatterHackers offers spools of it. The 240-270 print temperature should be doable, though it also calls for 130C bed temp...

jferguson
Posts: 163
Joined: Mon Mar 30, 2015 7:26 pm

Re: Polyethylene filament?

Post by jferguson » Sun Oct 23, 2016 12:24 am

Thanks, ksevcik, those are useful thoughts. Of course I could also try not to spill glue, but you know how that goes.

jferguson
Posts: 163
Joined: Mon Mar 30, 2015 7:26 pm

Re: Polyethylene filament?

Post by jferguson » Wed Oct 26, 2016 6:42 pm

It looks as though Delrin - Acetal is both available and highly glue resistant. The observations on printing it is that it retains heat and you really have to design for it - thin sections and so forth.

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