Recycling HDPE-2 plastic for model building.

Hi guys. Thank you for your input and comments. I parted off the first profile.
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On the back there is a big void. Despite compacting the plastic during the melting process these voids pop up now and then.
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If I had a mechanical drawing with measurements that I was trying to fabricate, the voids would be very problematic and frustrating to work around. But since I'm free wheeling it and just having fun with my lathe it's ok.
 
A few people have expressed concern regarding paint and glue adhesion with this plastic. I'm going to use this stuff.
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Thanks again for the feedback. More to come soon. Happy model building to all.
 
Can you do a test on the other bit with an ordinary primer I'd like to see the comparison..

Although eze38 is bang on describing what I vaguely knew, I'm still super interested to see if the release agent is already sufficiently dealt with by the process you have already completed.

Adhesion promoter is specifically for problem plastics like PP and HDPE and is sold along side bumper primer which may not specifically for this...

I only know about this because of the hasbro falcon (that is made of PP) thread and collectively we did a lot of tests early on with glues and different paints. Adhesion promoter came out best for priming and special rubberised ca glue won in that catagory :)
 
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Great,
I love turning and using wood for blasters and such always ends up feeling a little disappointing in the hand, this could be the answer (and a free material to boot) :)
 
I wasnt sure what you'd be doing with it in the end.. but chucking it up on the lathe was a nice surprise to see!

I know if I ever need to some similar.. I can follow along and put it on my lathe as well.. are the parts rigid/stiff? (like a hard plastic) or like 'rubber' with some flex in it?
 
Hello x197; surprisingly the plastic is quite rigid. I though it would be rubbery, but it's not. While I'm turning the plastic, It stands up to the pressure of the cutting tool and doesn't become deflected.
 
Yes, these voids are a problem because of un-even heated material. Somewhat difficult to do, but not impossible. The trick is always to maintain said piece hot...and then do a layering of that hot plastic. It will adhere to the other layers as long as it's in a very soft state. And that's the difficulty: you'll have to get a few ovens to go back and forth between pieces.
To heat up your form will also help a lot;)
 
Hi guys. Both of you are making very good points
The Piranha; I saw a video on You Tube where a guy used a heat gun to fill a void in HDPE-2 plastic. I think that would work well.
Joberg; I think you are right that this problem could be mitigated in the original heating process.
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I think the pieces I cut the plastic Tito are too big and course, and this is what is causing the voids.
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I will take the shavings that you see under the lathe and make another block of plastic paying special attention to compacting the plastic as its melting.
thank you for your input and ideas guys.
 
Pros:
Practically free
Machines nicely
Mechanically flexible but strong material
Non-stick type of material (Could be a benefit)
Not adding to landfill

Cons:
A lot of work cutting it up in small pieces
Must be cleaned of contaminants prior to melting
No-stick type of material (Difficult for glue and paint to bond)
Off gassing can be dangerous
Shrinks after cooling
Needs to be compressed when forming

Do I have this right? Feel free to add/change.

TazMan2000
 
polystyrene can be melted in the same fashion, FWIW I used a food grade silicone cookie sheet, I have tried to melt sprues into a silicone mold, with varing success. The smaller the plastic piece the better, as far as getting it to conform without air bubbles.
 
I think If i have a go at this I would use milk bottles as the cleaning of those would be relatively easy, compared to say oil or some detergent bottles.
We must get through 20-30 pint size bottles a week at work. I think cutting the pieces smaller would def help a lot.
I like the look of the bigger pieces but if painting it obs doesn't matter :)
 
Hi guys; thank you for your input and interest in my little experiment.
Joberg; I have seen a video on You Tube where a guy used a blender to grind up the plastic with very good results. I have also seen where a crosscut paper shredder is used with fantastic results, and it works supper fast too. If I make a commitment to doing this on a regular basis I will get a paper shredder dedicated to grinding up plastic.
TazMan2000; Your list sums it it so far.
Memyselfi; I may try this with styrene. However, styrene doesn't machine well.
Spacebob; recycling milk containers is a great idea because the plastic is so thin. I think it would work very well if it's processed through a paper shredder.
 
Here is another widget I turned on the lathe.
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There is a big void in the back.
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I have been saving the shavings and I'm going to use them to make another hunk of plastic. Because the plastic is chopped up so finely, I'm hoping it will fix the issue with the voids in the plastic.
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More to come soon. Thank you for looking.
 
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