# Reclaiming Polyethylene Pipe



## MrWhoopee (Feb 18, 2022)

I have over 100' of 1-1/4" 125 psi black poly-pipe that came out of the (dry) well that I pulled. I could cut it into 3.5' lengths and put it in the recycle bin, but, due to the pandemic, the garbage service is not processing recyclables, they are just going into the landfill. I also hate wasting something that is potentially useful. I've decided to try  cutting it up and melting it into slabs for future use. PE has a melting point around 250° F, so I did a test melt in my shop toaster oven. It worked, but the plastic did not melt uniformly or completely. Portions of it liquified, but the skin of the pipe remained semi-solid. It did seem to form a solid, if not homogenous, piece once cooled. I've seen videos of people doing this with milk jugs, etc., but I wasn't really impressed with the results. Has anyone tried this?


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## Cadillac (Feb 18, 2022)

Would think the fumes would kill you in the process. Idk but not worth it in my book. I like metal plastic breaks!


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## MrWhoopee (Feb 18, 2022)

Cadillac said:


> Would think the fumes would kill you in the process. Idk but not worth it in my book. I like metal plastic breaks!


No noticeable fumes at temps up to about 300° F. If you've ever machined UHMW, you would know that some plastic doesn't break, not even when you want it to.


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## Reddinr (Feb 18, 2022)

Do you have a "second use" (or similar) store nearby?  We have those here and you can just drop off good stuff like that.  They gladly take it and resell it for a low price to keep the business going.  Saves on landfills, helps people that are stretched on a budget (and cheapos like me).  I almost always walk away finding some great used tools for little $.


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## strantor (Feb 18, 2022)

Here's the first of a 3 part series, the info you need is in this one and half the next one.






Well, maybe not the _info_ you need, but the proof that it can be done with good results. Granted this guy is working with brand new buckets instead of old pipes that spent their life immersed in dirt and water, but I think it should still be feasible if you knead it up like taffy, like these guys do:


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## MrWhoopee (Feb 18, 2022)

strantor said:


> I think it should still be feasible if you knead it up like taffy, like these guys do:


I was hoping to just do a melt and call it good, but the results of the test melt suggest kneading might be needed. I did cut the test melt in half, it shows no evidence of internal layering, just one solid piece. Over mama's objections I have an 8x12 baking pan in the oven trying a larger quantity.


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## ericc (Feb 18, 2022)

This works.  You just need a higher temperature.  The plastic pieces conduct heat poorly.  Even though 250 is close to the melting point, conductivity of the plastic feedstock is low and It helps to have some degree of superheat.  I found that over 350F, like 400, works much better.


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## MrWhoopee (Feb 18, 2022)

ericc said:


> This works.  You just need a higher temperature.  The plastic pieces conduct heat poorly.  Even though 250 is close to the melting point, conductivity of the plastic feedstock is low and It helps to have some degree of superheat.  I found that over 350F, like 400, works much better.


Turning the oven up as we speak. Just trying to avoid too hot. I promised mama I wouldn't foul the oven or stink up the house. Anybody know what the smoke point is?


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## strantor (Feb 18, 2022)

MrWhoopee said:


> Turning the oven up as we speak. Just trying to avoid too hot. I promised mama I wouldn't foul the oven or stink up the house. Anybody know what the smoke point is?


No but I think you're about to tell us....


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## RJSakowski (Feb 18, 2022)

I have been experimenting with various plastics in a deep fat fryer.  I have tried polypropylene ans PET with promising results. I changed the thermostat to cycle at a slightly higher temperature.    As manufactured, it would reach 400ºF and I raised the setting to around 500ºF.  The big problem I have now is radiant heat loss so my next step is to insulate the wall of the fryer.


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## strantor (Feb 18, 2022)

I'm glad to see there is more interest in plastics. I have been wanting to give it a try ever since running across the "precious plastics" videos on youtube but just haven't had time. I'm curious to see what direction you guys go with this stuff.


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## ericc (Feb 18, 2022)

Here is a jack puck.  It is used to cradle the seam of the frame on modern cars without flat jacking points.  Also shown is the temporary one made out of wood.  Wood breaks, as it is easy to see.  Note that I was entirely prepared for the eventual break and there was nothing under the car to be crushed when it settled suddenly.


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## MrWhoopee (Feb 18, 2022)

RJSakowski said:


> I have been experimenting with various plastics in a deep fat fryer.  I have tried polypropylene ans PET with promising results. I changed the thermostat to cycle at a slightly higher temperature.    As manufactured, it would reach 400ºF and I raised the setting to around 500ºF.  The big problem I have now is radiant heat loss so my next step is to insulate the wall of the fryer.


I'm back out in the shop, using the toaster oven, and experiencing the same problem. With the thermostat set at 400º F the poly is about the consistency of refrigerated honey. Got my first slab out. Not pretty, but still encouraging. Looks like a pan of burnt brownies.


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## strantor (Feb 18, 2022)

MrWhoopee said:


> I'm back out in the shop, using the toaster oven, and experiencing the same problem. With the thermostat set at 400º F the poly is about the consistency of refrigerated honey. Got my first slab out. Not pretty, but still encouraging. Looks like a pan of burnt brownies.
> 
> View attachment 397035
> View attachment 397034


If it were mine I'd call it a success. I would like to see those holes filled in but something functional can surely be made from that. 

Did you knead it or is that straight out of the oven?


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## MrWhoopee (Feb 18, 2022)

strantor said:


> If it were mine I'd call it a success. I would like to see those holes filled in but something functional can surely be made from that.
> 
> Did you knead it or is that straight out of the oven?


I kneaded, pressed, clamped, etc.

It's a very solid piece, most of it a little over 1/2" thick. I need more heat and a better release agent.


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## RJSakowski (Feb 18, 2022)

One thing that I noticed is that there is a fairly large difference between the melt point and the free flow temperature.  

The experiment that I did with PET was encouraging, The slug I ended up with was free from air bubbles and seemed to have fairly good mechanical properties.  I need to repeat with a higher temperature and larger sample. 

There must be a point at which the plastic is free flowing as injection molders start with pellets so there will be a lot of initial air inclusion.


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## woodchucker (Feb 18, 2022)

MrWhoopee said:


> I have over 100' of 1-1/4" 125 psi black poly-pipe that came out of the (dry) well that I pulled. I could cut it into 3.5' lengths and put it in the recycle bin, but, due to the pandemic, the garbage service is not processing recyclables, they are just going into the landfill. I also hate wasting something that is potentially useful. I've decided to try  cutting it up and melting it into slabs for future use. PE has a melting point around 250° F, so I did a test melt in my shop toaster oven. It worked, but the plastic did not melt uniformly or completely. Portions of it liquified, but the skin of the pipe remained semi-solid. It did seem to form a solid, if not homogenous, piece once cooled. I've seen videos of people doing this with milk jugs, etc., but I wasn't really impressed with the results. Has anyone tried this?


@RJSakowski showed a block that he created to make a drill bit or end mill holder. He got me interested, because I like the idea of working with plastics that are recyclable like this.


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## woodchucker (Feb 18, 2022)

MrWhoopee said:


> I'm back out in the shop, using the toaster oven, and experiencing the same problem. With the thermostat set at 400º F the poly is about the consistency of refrigerated honey. Got my first slab out. Not pretty, but still encouraging. Looks like a pan of burnt brownies.
> 
> View attachment 397035
> View attachment 397034


It really does look like brownies. Can you send that my way.

I would say that's a success. That's a very usable block.
That'll machine well I think.


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## Larry$ (Feb 18, 2022)

I'd like to see more about melting plastic into something usable. My trials were less than fully successful.


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## Bi11Hudson (Feb 19, 2022)

Larry$ said:


> melting plastic into something usable


As a rule, I *avoid* plastic but do use it. Even for my model trains. . . The one point I will concede is that it's a good electrical insulator, especially at low voltage of 600 volts or less. Otherwise, *plastic is like metal for making useful parts*. It can be machined, the point of this site. And it can be cast, usually in an injection mold. It is nowhere as strong as metal but for making small parts like knobs and handles it is as, or more, useful than metal. And best of all, once the details are worked out, it's cheaper. 

.


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## woodchucker (Feb 19, 2022)

strantor said:


> Here's the first of a 3 part series, the info you need is in this one and half the next one.
> 
> 
> 
> ...


I liked the way he layered it and came up with the nice colors. Great looking.


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## addertooth (Feb 19, 2022)

I would be tempted to recycle it by making "useful objects" out of them in their current shape.  i.e.  Shipping tubes.  Cut them down and sell them on eBay for those who need to send documents/drawings/posters/drafts.   Or possibly small camping tables, designed to be popped apart.  Possibly a large scale windchime-whistle?  

I use rigid tubing to ship expensive restored antique fountain pens to the purchaser. Unlike carboard tubes, I would dare the USPS to crush a thick walled plastic/PVC tube.  Then again, you should never dare the USPS to break anything, to include a Tungsten brick.


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## RJSakowski (Feb 19, 2022)

My desire to reclaim plastics by melting them down is more about reforming them into a shape that I need.  For the most part, I wouldn't use the reclaimed plastic for items where I needed structural integrity  but rather a large chunk of material.  Plastic has an advantage in that it is relatively inert and it doesn't shrink  or change form. Reclaimed plastic is also readily available.  I haven't totaled it up but we (the wife and I) probably throw away a lb. or two a week.  We heat with wood, and polyethylene and polypropylene are simple hydrocarbons so they are repurposed as fuel.  More complex plastics like acetal, pvc, and polystyrene create undesirable combustion products so they go into the recycle bin,  

The problem with recycling is that it often takes more energy to process them than what is saved.  A good indicator is whether or not the recycler pays you or charges you to haul the stuff away.  A lot of the recycled material just ends up in a landfill somewhere.  NYC is notorious for shipping their waste to "somewhere  else".


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## DAT510 (Feb 19, 2022)

Depending on the intended manufacturing method, a given Plastic Resin will have different Melt Flows.  The Melt Flow is the measurement of how Liquidity or "Molasses" like a polymer gets when it is melted.  Tubing is typically extruded and tends to have a lower melt flow (more "Molasses" like) since it needs to hold its integrity as it exits the extruder and travels to the water bath,  while the same resin when used for injection molding would have a high melt flow, as it needs to flow through and completely fill the molds.

So in other words.  Raising the temperature beyond the melting point won't significantly change the Melt Flow of the polymer, but you can start to burn the polymer.

Also, it was common to cross-link Polyethylene (PE) Irrigation Tubing to give it strength and durability .  Cross-linking also makes the tubing very hard to melt, if at all.   Heat shrink tubing is typically a form of Cross-linked PE.


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## MrWhoopee (Feb 19, 2022)

DAT510 said:


> Depending on the intended manufacturing method, a given Plastic Resin will have different Melt Flows.  The Melt Flow is the measurement of how Liquidity or "Molasses" like a polymer gets when it is melted.  Tubing is typically extruded and tends to have a lower melt flow (more "Molasses" like) since it needs to hold its integrity as it exits the extruder and travels to the water bath,  while the same resin when used for injection molding would have a high melt flow, as it needs to flow through and completely fill the molds.
> 
> So in other words.  Raising the temperature beyond the melting point won't significantly change the Melt Flow of the polymer, but you can start to burn the polymer.
> 
> Also, it was common to cross-link Polyethylene (PE) Irrigation Tubing to give it strength and durability .  Cross-linking also makes the tubing very hard to melt, if at all.   Heat shrink tubing is typically a form of Cross-linked PE.


Thanks, this is exactly the kind of info I need.

This stuff melts (softens) fairly readily but only partially liquefies. The "skin" of the pipe softens like taffy but does not liquefy. The pipe is at least 30 years old, so this may be due to age. In the "burnt brownie" test, I cut the pipe into 12" lengths, then quartered those lengthwise (I LOVE my little vertical bandsaw  https://www.hobby-machinist.com/threads/a-vertical-bandsaw-for-a-small-shop-and-budget.94300/). I laid them in a baking pan like making lasagna. Going to experiment with different arrangements to see if I can minimize the effect of the skin, or at least get it more evenly distributed.


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## matthewsx (Feb 19, 2022)

One would think chopping it up into smaller pieces would improve the process. How about building a machine to preprocess your material prior to melting?


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## MrWhoopee (Feb 19, 2022)

matthewsx said:


> One would think chopping it up into smaller pieces would improve the process. How about building a machine to preprocess your material prior to melting?


It had crossed my mind and would be the obvious choice if I was going into the business. Looking at my old chipper/shredder, but it's an old "beater bar" type and this PE is tough and not easy to shred. I'm certain I can get usable material the way I'm going, just trying to reduce the oven time and labor required.


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## Bi11Hudson (Feb 19, 2022)

A miniature wood chipper?


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## MrWhoopee (Feb 19, 2022)

addertooth said:


> I would be tempted to recycle it by making "useful objects" out of them in their current shape.  i.e.  Shipping tubes.  Cut them down and sell them on eBay for those who need to send documents/drawings/posters/drafts.   Or possibly small camping tables, designed to be popped apart.  Possibly a large scale windchime-whistle?
> 
> I use rigid tubing to ship expensive restored antique fountain pens to the purchaser. Unlike carboard tubes, I would dare the USPS to crush a thick walled plastic/PVC tube.  Then again, you should never dare the USPS to break anything, to include a Tungsten brick.


Unfortunately, this stuff has a large radius (~10') curve to it and is almost 2" dia. It's like the industrial version of 5/8" drip emitter tube.


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## DAT510 (Feb 19, 2022)

It's also possible the tubing was co-extruded, which means it has multiple layers.  It could have an outer layer which resits abrasion, etc, and a more "pure" PE inner layer for potable water contact.  This may be the reason your seeing a outer skin that appears to melt differently.


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## MrWhoopee (Feb 19, 2022)

DAT510 said:


> It's also possible the tubing was co-extruded, which means it has multiple layers.  I could have an outer layer which resits abrasion, etc, and a more "pure" PE inner layer for potable water contact.  This may be the reason your seeing a outer skin that appears to melt differently.


This^^^^!
The OD and ID both exhibit this skin.

I flycut both sides of the burnt brownie down to 1/2" thickness (+/- .020). It machines pretty nicely with a sharp HSS tool, the floor was covered with little, black curlies that looked like rat turds.





I really can't complain for a first attempt. 

The next try is cooling now.


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## MrWhoopee (Feb 21, 2022)

Test #2, I thought I'd try it this way.




It was a bad idea.




The skin on the inside is visible. 
I used a 2.5 dia. piece of teflon to roll and press the poly to fill the voids. It was partially successful.
The finished plate was much thicker than the first, but was below 1/2" after cleanup and had some major voids.
I could also clearly see some lines where the skins had been.

I decided to make the non-melting skins work for me. I went back to quartering the pipe and laying the pieces horizontally in the pan, with each successive layer at 90º to the previous. This puts the skins in horizontal layers parallel to the thickness of the plates, like laying up fiberglas.




I would heat each layer until substantially softened, then roll it with the teflon (it tends to draw up shorter) along with adding bits to fill any voids before adding the next layer. It's labor intensive, but what else do I have to do?

Still need a good mold release suggestion, the pan is getting pretty beat up. Canola didn't help much, neither did way oil.


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## RJSakowski (Feb 21, 2022)

The skin on the pipe may may a thin film of deposits from the water.  Our water is fairly hard and also contains iron and anything carrying it eventually builds up a coating.  You might try a wipe down with muriatic acid followed by a rinse.

Oils most likely won't work for a mold release as they would dissolve into the plastic.  My plan was to just use old cans as disposable molds and peel them away.  A 1 gallon solvent can cut lengthwise would be a candidate for a larger mold.  Quart solvent cans foe smaller pieces..


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## MrWhoopee (Feb 21, 2022)

RJSakowski said:


> The skin on the pipe may may a thin film of deposits from the water.  Our water is fairly hard and also contains iron and anything carrying it eventually builds up a coating.  You might try a wipe down with muriatic acid followed by a rinse.
> 
> Oils most likely won't work for a mold release as they would dissolve into the plastic.  My plan was to just use old cans as disposable molds and peel them away.  A 1 gallon solvent can cut lengthwise would be a candidate for a larger mold.  Quart solvent cans foe smaller pieces..


The skin (ID and OD) is definitely from the extrusion process. Our well water is remarkably free of dissolved minerals, flowing directly down from the snows of Mount Lassen.

I have a surplus of round Danish Butter Cookie tins, which I was considering using, but I would prefer rectangular to reduce waste. It's also easier to cut the pipe to fit a rect. mold.

Since I will have to machine all surfaces, I may go back to using foil to line the mold.


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## francist (Feb 21, 2022)

I know this is a serious experiment and I’m following the results with interest, but, I have to say the accompanying images of black plastic cannoli and cinnamon rolls in baking pans is mildly amusing…


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## MrWhoopee (Feb 21, 2022)

francist said:


> I know this is a serious experiment and I’m following the results with interest, but, I have to say the accompanying images of black plastic cannoli and cinnamon rolls in baking pans is mildly amusing…


I was thinking cinnamon rolls too.


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## MikeInOr (Feb 21, 2022)

Every episode of "How it's made" I have watched where they are making something out of plastic they always start with plastic beads from the plastic producer.  I am trying to think of some way to grind up small batches.  The only thing I can think of is to cut it with a saw and collect the "saw dust" and little pieces (maybe a big roughing mill?).  Just a thought to spur some additional thinking...

Instead of a tray how about a tin can.  Melt the plastic in the tin can then strip the tin can off the outside when the lump has cooled.  Just another though to spur some additional thinking...

Another thing I notice is the hot plastic is almost always extruded.  Either into finished pieces or into a blow mold to create a hollow shell... but almost always extruded.  Just another thought to spur some additional thinking...

Mold Release... a silicon baking matt?  Again, just a thought. (Of course you will have to wait until the wife is at the store or similarly out of the house).

Most of the "How it's made" episodes have very highly polished steel molds????  The blow molds also have water running through them to cool the plastic rapidly.

P.S. I love your experimentation!







						Plastic Injection Mold Release Agents | Maverix Solutions
					

Maverix Solutions understands the need for mold release agents, mold cleaners, rust preventatives and lubricants in the injection plastic molding industry.  Our unique chemistry makes our mold release coatings highly specialized for the release of all thermoplastics materials during injection...




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			https://www.amazon.com/Smooth-Universal-Mold-Release-fl/dp/B004BNHLOK
		


(I am not suggesting you buy a mold release.  Just seeing what is out there.  WD40?)

Maybe it would help to melt and mix in one container then put it into a separate container for molding?  (Cooking WD40 does not sound like a good idea but maybe it could be a release in the molding container?  Wax paper in the molding container?)


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## woodchucker (Feb 21, 2022)

gotta question. I have many tool cases, the blow molded cases for routers, drills, my bandsaw.. A few that I threw out. Is this polyethylene  usually?

If it is, I think I'll make some plastic brownies this week.


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## RJSakowski (Feb 21, 2022)

woodchucker said:


> gotta question. I have many tool cases, the blow molded cases for routers, drills, my bandsaw.. A few that I threw out. Is this polyethylene  usually?
> 
> If it is, I think I'll make some plastic brownies this week.


Check for the recycling logo.  A triangle with a number inside.  Most recent plastic products have them in an unconspicuous spot. HDPE is a 2,.  PP is a 5 and PET or PETE is a 1.  PVC is a 3, LDPE is a 4, and PS is a 6.


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## woodchucker (Feb 21, 2022)

cool, I'm showing a 2 on the Milwaukee case. gotta check the others... instant material.

edit yep, the others are 2... Man , now I am upset that I got rid of those other cases last year.  Lots of good material... I'll be baking this week.


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## MrWhoopee (Feb 21, 2022)

Been trying to think of a practical way to grind the pipe. Almost borrowed the food processor........


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## woodchucker (Feb 21, 2022)

MrWhoopee said:


> Been trying to think of a practical way to grind the pipe. Almost borrowed the food processor........


I was thinking of the food processor, but after seeing one of the videos, the best would be to take a paper shredder and supersize the power ..
take the shredder bars and put them in a new housing with a big A** motor.


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## FOMOGO (Feb 21, 2022)

Meat grinder maybe?


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## f350ca (Feb 21, 2022)

Wood chipper
?


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## woodchucker (Feb 21, 2022)

according to the videos I watched, the PE must be clean. so wood chipper... only if you can get it spotless.
I have to admit, that watching that video with the guy making slingshots was cool artwork. That was good to know... If I want to become an artist I can


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## rabler (Feb 21, 2022)

Due to internet restrictions I only watch YouTube videos when insomnia strikes, as the quotas change from 2am - 7am (?).   It does mean I watch some odd stuff, but this one is relevant:


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## Winegrower (Feb 21, 2022)

I love you guys.   For some reason, the thought occurs to me that in retirement, work expands to fit the time available.


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## rabler (Feb 21, 2022)

Winegrower said:


> I love you guys.   For some reason, the thought occurs to me that in retirement, work expands to fit the time available.


Wait, that only happens in retirement?  Was I doing something wrong before?


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## woodchucker (Feb 21, 2022)

Damn, I just recycled most of a shredder, I have some of it left, but I recycled the spacers already. I can make new ones... but they were already cut out for the hex bar....
	

		
			
		

		
	




I'll need a new baking pan too, this one won't fit the little toaster oven I use for tempering.


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## MrWhoopee (Feb 21, 2022)

woodchucker said:


> I'll need a new baking pan too, this one won't fit the little toaster oven I use for tempering.


I suggest lining with foil. Non-stick coating might work, but we won't know until someone tries.


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## MrWhoopee (Mar 4, 2022)

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.



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.




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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## f350ca (Mar 4, 2022)

recycling the chips is approaching pellets.

Greg


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## MrWhoopee (Mar 13, 2022)

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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## MrWhoopee (Mar 14, 2022)

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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## brino (Mar 15, 2022)

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


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## brino (Mar 15, 2022)

Found it:

https://www.hobby-machinist.com/threads/stoner-mold-release-spray.95170/

I wonder if that would work for this purpose?

Brian


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## MrWhoopee (Mar 15, 2022)

Conveniently mounted on the operator side of the machine.


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