The Search for a Plastic Grinder

[Dauntless]

I'd really like a crack at using recycled plastic for all sorts of things I've learned to do with it. If I had the tools.

My number one problem is a plastic grinder. What I want is to have pulverized granules, such as used in rotomolding such things as plastic trashcans. I could mix that in plaster when making low volume molds that will last longer, in the concrete when I replace my cracked patio with one that won't crack so much, etc. Maybe even do that rotomolding.

But do you know what those machines COST? Assuming I can pay for it, do I want 480 volt? Uh, noooooo. Oh, I must want the 240 volt 3 phase power unit. Well, I'm in a residential neighborhood so there's no 3 phase power, in fact my garage has a 15 amp breaker on the 120 volt outlet. At this point if I was on the phone they'd be hanging up. I sure don't get much EMail response, even from the company whose website claims to offer a DOMESTIC unit.

So I'm looking for an alternative to the proper device. In your kitchen right now, what do you have that's harder than plastic? What about ice? I think of those Slurpees, Icees, etc. That might be a good size. A $20 unit probably wouldn't hold up long, but maybe something the restaurant industry uses. Say, $180?

http://www.cisinks.com/new-ice-shaver-maker-sno-snow-cone-icee-shaved-machine-p-1153.html

Just wondering if someone else as any ideas.

[youtube]XvZYafH6ALw[/youtube]

 

[Harold in CR]

What about a grain mill ? They are used to grind corn, which is pretty hard.

 

[Ypedal]

well.... it's a long shot...

but my grandfather built a potato grinder to make acadian poutine
https://www.google.ca/search?q=acadian+poutine&source=lnms&tbm=isch&sa=X&ei=rCG9Ufq8Mo_-rAHw8YGoCw&sqi=2&ved=0CAcQ_AUoAQ&biw=1024&bih=653

" une Rape a patate " .. in french.

Basically, a flat sheet of thick metal is pierced with a nail 100's of times, then rolled into a tube that looks like a killer cheese grater.. , this is attached to a shaft and spun with a washing machine motor ( any motor capable of a few 100 w )

Think small scale mulcher.. i'll get some pics tomorrow, my neighbor has one.

 

[Dauntless]

Well, an uncooked potato is good and hard if that's when he grinds them, but I get the idea that would basically just shred plastic. My first choice would be powder, my second is like coffee grounds. (Coffee beans aren't so hard, right?)

 

[Hillhater]

Why dont you ask Tom Dickson at Blendtec..
http://www.youtube.com/watch?v=MC8Zvl-8ziA
http://www.youtube.com/watch?v=lAl28d6tbko

 

[The fingers]

I had a similar idea, to recycle road dust; the blend of sand and tire rubber dust that lines the gutter and then runs off into the ocean when it rains. It could be recovered and incorporated into asphalt slurry mix.
The problem with running plastic through a grinder would be heating of the material and gumming up or tangling in the works, and creating a suitable product. If the raw material was supercooled first, maybe it would shatter instead of melt; or you could melt it first, forming it into sheets that harden as they cool. You could then shred/grind them through a surplus large office shredder. My small wastebasket shredder devours credit cards, but I havn't tried running plastic bags through it or putting something like that in my Magic Bullet that I use to grind coffee beans.
Keeping all that stuff out of the ocean is great, and recycling needs to begin with us. Around our community so much is wasted and most of it ends up in landfills, or in the air and water.

 

[JEB]

I wanted to re-cycle Styrofoam packing, once ground up combined with Hendrys 107 water base roofing material, it would make a light weight filler material for leveling out ponding areas on a flat roof. I bought a bunch of 7.5 inch carbide saw blades from harbor freight stacked them together in a in closer that had holes in the bottom the size of the particle I wanted, feeding the foam in the top of the rotating blades, through a smaller opening, particles fell out the bottom. Worked best with a fine spray of water to keep the static electricy down.

 

[The fingers]

The guy at the Costco roadshow in HB today with the $499 hot/cold blender said it would pulverize plastic bags into powder. Wether that is true or not, I don'know. :? It makes spinach smoothies and tortilla soup also.

 

[bee]

Lots of info here: http://forums.reprap.org/read.php?1,26367,page=1

 

[Dauntless]

Truly turning a bag to powder is a tough one because they flex and flop around, but if it does it, GREAT!

EPS foam, which some people refer to as Styrofoam even when it's not blue, will dissolve in citrus oil. If you're not familiar with it, it's the greenER (Jury is out on how much better it is) alternative to acetone. It's a little slower in dissolving it than acetone but it works and it smells better. You can shape or cold mold and it'll set and you can make things from EPS or even nonEPS styrene, though EPS is faster to dissolve.

Sand and tire rubber dust. What acts as the binder? Portland cement refers to the method of the binder, I'm not an expert so I won't begin to try to explain. Papercrete refers to the fact that cardboard acts as a binder itself, so you can make a lighter, near as strong as concrete surface. They do use recycled glass in glasphalt, old tires do go into a composite for road surfaces, but I don't know the extreme of what you're talking.

No heating and no cooling desired for grinding. Meat grinders just make big pieces. I don't want to deal with a home extruder, those guys wanting to make ABS (One tough, high temp material) and extrude it at home don't know what they're trying to bite off. I think I put up a video of the home extruder the guy was offering on Kickstarter, his was only the early prototype for the unit he wanted money to develop, but it was still beyond practical even for the seriously hands on type. I'm talking about a simple process much like things people already do, just using free scrap plastic which contains some serious potential

My first choice would be plastic dust. Next would be plastic grains/sand. Flakes are just too big. I need what you might call liquefaction so that it'll flow even before it melts. When they rotomold even containers that are bigger than us they grind the plastic pellets down to granules or even powder. I do believe I have to give up on finding someone who builds a little "R&D suitable" plastic grinder to give me the pulverization with a small unit that doesn't require industrial power. The thought occurs to me that there's some hard foods out there that get processed by machines and restaurants usually don't have industrial power. Some people are serious chefs in their own home. Caterers need devices they can use anywhere. I can't imagine a paper shredder standing up to feeding high density polyethylene (2) or polypropylene (5) through it. Something that can grind ice or an iPad (That video is http://www.youtube.com/watch?v=lAl28d6tbko ) seems promising. These are the less readily accepted by the recycling centers material that are actually best for the things I'd like to do.

Tom Dickson looks like he's coming close to what I want. I could sift out the flakes and regrind them. THIS THING COULD ACTUALLY WORK! I'm EMailing the company and sending them this link. If they make a similarly effective coffee grinder like that, even better.

Dang, this thing survives a piece of BORON in it? I'm getting the idea this could work.

[youtube]xRAz6fkr5RQ[/youtube]

 

[Dauntless]

Note how the supple materials don't pulverize as well. Sometimes they use a two step process where the first step shreds or chunks then the second step pulverizes. I wish they'd shown what the fiberglas insulation looked like afterward. I was gagging on the dust just thinking about it.

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[dogman dan]

Could you use shavings? A power planer will make shavings from plastic easy. Maybe take a table saw, then stack three coarse tooth carbide blades on it to cut a half inch wide kerf. then set the fence to almost touch the blades. That should make chunky plastic sawdust.

But you WILL need a tool to push the plastic through, if it jams, it will suck your fingers right into it. Have nothing fragile on the other side of the saw too, so you don't fling stuff through windows.

 

[Sancho's Horse]

I had some HDPE which I needed to shape, and I used my router. It cuts and shapes nicely. The router started off producing large shavings, but as the bit lost some of its edge it created fairly fine shavings/dust. Only problem was the heat eventually would get too high. Unfortunately, this process required a chunk, and most of the plastics you could recycle do not come in chunks.

 

[Harold in CR]

A small hammer mill might be what you need. It has swinging blades in it, that smash the product and allows the smaller stuff to fall through punch plates of different size holes. It takes corn for example and creates cracked grains along with coarse powder and some dust. It gets warm but not hot.

 

[e-beach]

From this site: http://www.instructables.com/community/Inexpensive-way-to-grind-plastic-bottles/

I worked in a sponge rubber factory one summer when I was in high school. To recycle the scraps we ran the sponge rubber through a special chunking machine the chunks were then mixed with binders, packed in a mold, steamed to set the binder, and pealed to make under padding.

The chunking machine was, (drum roll please)

A stack of spinning coarse saw blades with spacers between the blades.

You could do the same with fine carbide toothed saw blades with washers as spacers mounted on a shaft and driven with a motor and pulley.

Sounds like a reasonably inexpensive and customizable approach. Or you can just get a double boiler, melt the plastic and pour it into some sort of molds. If all you want to do is use the plastic as filler for cement then molds made out of wet mud in your back yard would be fine.

 

[Dauntless]

NO MELTING! The idea is to work with it in as close to a fine powder as I can get it at room temperature. Coffee ground sizes are probably okay. (I'm thinking of coffee beans as relatively soft so the machine might not be tough enough.) It's supposed to pour and mix at room temperature. Maybe I might even experiment with fume technology, but that's beyond me today.

http://www.jordanreductionsolutions.com/blog/the-difference-between-shredding-grinding-and-granulating/ The article explains. Unfortunately they only make the large factory units. Any shredding, shaving, chipping unit isn't good enough, but if I found someone that only really worked if the parts had that sort of reduction first I might need to go two stage.

The existence of machines that pulverize plastic is for the sake of functions as with rotomolding, where the not yet heated mold begins to rotate and the plastic inside needs to pour about as though it was liquid while the mold heats. If you're familiar with sintering metal, they work with powdered form. Pulverizing plastic is a big obstacle to the otherwise simple process of rotomolding, as beads or even flakes are not reliably even in the process. Meanwhile, plasticrete shows a resistence to thermal expansion and therefore doesn't crack so easy, just the thing for plaster mold making. (Plaster IS concrete, what we now call plastic is NOT what the word was originally applied to.) Flakes or chips cannot be melted in the process, the thermal reaction in concrete setting is relatively low temp.

The problem with something like a ball mill is you spend a fair amount of time producing a small amount of powder, not such a big deal when it's metal powder, but someone making plasticrete might want 60 pounds to go with a 90 pound bag of concrete, how long would that take with a ball mill? Should be quicker than metal, but. . . . It would definitely require creating chips or flakes first. http://www.instructables.com/id/Make-German-Dark-Aluminum-Powder/?ALLSTEPS

But extruding filament or even sheets with homemade equipment? (I'd love to make sheets for vacuum forming.) I see the machines on YouTube and I want to ask if they're REALLY getting a reasonable production rate from those things.

http://www.kickstarter.com/projects/rocknail/filabot-plastic-filament-maker

http://www.youtube.com/watch?v=K1a1QB4h1oA&sns=em

http://www.facebook.com/FilaMaker