Recycler! New Gada Prize team!

Re: Recycler! New Gada Prize team!

jbayless — Fri, 29 Jun 2012 12:24:34 -0400

JohnnyCooper Wrote:
> Is anyone else having trouble visualizing why an
> auger would drive material forward at any real
> pressure? Shouldn't the plastic granules just
> tumble to the front of the screw and then spin
> clogging the flutes?

The forward pressure actually comes from friction against the outer tube. Ideally, the plastic will have zero friction with the screw threads, and lots with the inner face of the outside tube. Imagine plastic sticking to the inner surface of the tube, as the screw rotates -- the screw threads will encounter it and force it forward. This is one reason why a tight clearance mate between the screw and the tube is important.

Alternatively, imagine plastic just going around and around as the screw turns, without moving forward (this happen in the reverse case - lots of friction with the screw, none with the surrounding tube, like if you used a PTFE sleeve or something). Imagine that we then crank up the friction on the surrounding tube. The molten plastic travelling around in a circle will shear against the tube, making it want to rotate more slowly than the screw. This will cause it to encounter the screw threads and get pushed forward.

It does take some thinking about, because it's not a simple idea. =)

Re: Recycler! New Gada Prize team!

CBH — Sat, 23 Apr 2011 05:31:06 -0400

Can't you just melt the plastic into shape through a metal funnel, glue gun filament tube and a press to keep it moving through?

Re: Recycler! New Gada Prize team!

Have Blue — Fri, 03 Dec 2010 21:56:22 -0500

I came across a paper today that might be of interest - "Recycling of RP Models by Solution – Casting Technique":
[utwired.engr.utexas.edu]

Re: Recycler! New Gada Prize team!

Satori — Thu, 14 Oct 2010 23:27:20 -0400

SebastienBailard Wrote:
-------------------------------------------------------
> Is this thing supposed to be self replicating,
> easily sourced, or completely open to vitamins?
> The recycling part of the toolchain? Anything
> goes.
>
> Tim from Michigan-RUG mentions that some buddies
> have achieved good results powdering plastic
> chunks using a rock tumbler. :D

Seen this? Might we be able to melt plastic, and have the option of making either gasoline or more plastic from it?

It seems this method doesn't require pelletizing before recycling. Also, by re-forming the plastic from the recycled materia people would have the option of creating it in whatever shape they prefer. Like spools of 'spensive plastic the RepRap currently uses.

Re: Recycler! New Gada Prize team!

JohnnyCooper — Fri, 06 Aug 2010 03:52:00 -0400

Great to see progress on this front. I'm currently working on making ABS granules/chips/powder for my Injection molding machine so I'll try and see if I can come up with a good way to grind up plastic of odd shapes and sizes. It may be best to just melt it in a skillet and cast it in to rods to be cut up. If plastic degrades with multiple thermal cycles, perhaps the slurry can be fed directly to the auger recycler in liquid state?

Re: Recycler! New Gada Prize team!

Cefiar — Thu, 05 Aug 2010 23:04:05 -0400

Johnny: As has Capo. [capolight.wordpress.com]

He's got a way to go, sure, but then so does VU. He's also posting quite a lot of good material on his blog about all sorts of stuff related to recycling (including polymer degradation and how it affects recycling).

Re: Recycler! New Gada Prize team!

JohnnyCooper — Thu, 05 Aug 2010 13:46:59 -0400

[hackaday.com]

Victoria University students beat me to getting an auger working.

Brilliant design! The wood drill bit was a great choice. Would a waterbath help stabalize the filament diameter?

Is anyone else having trouble visualizing why an auger would drive material forward at any real pressure? Shouldn't the plastic granules just tumble to the front of the screw and then spin clogging the flutes?

In any case: Next step is to convert scrap parts in to granules. Garbage Disposal?

Re: Recycler! New Gada Prize team!

r250r — Thu, 01 Jul 2010 23:04:39 -0400

re: pump/plunger extruder (Prober, rocket_scientist)

You might want to take a look at the design of a agricultural hay baler - specifically, the "small square baler".

It uses an auger, a fork, and a plunger. There are other parts to a baler - such as the pickup, needles, and knotter, but they wouldn't be useful in this application.

The auger collects material (plastic bits, in our case) for the fork to grab. The fork is attached to a special linkage which causes it to move in an oval. It is also timed to the plunger so they won't collide. While the plunger is retracted, the fork drags material into the compression chamber. It then lifts and extends to grab more material as the plunger starts to advance.

When the plunger advances, a knife blade on the fill side of the plunger cuts off anything sticking out of the compression chamber. The walls of the chamber have catches which spring out a little to grab the material, so that there is room for more material.

I didn't find any really good videos, but this one should help a little.
[www.youtube.com]
The plunger is moving towards and away from the camera. You can't see the face of the plunger, but you can see the back of it and it's crank.

Mark

Re: Recycler! New Gada Prize team!

JohnnyCooper — Mon, 21 Jun 2010 07:10:47 -0400

$30 dollar meat grinder waiting for a spool extruder nozzle plate to be measured->designed->turned on lathe.

[www.amazon.com]

Re: Recycler! New Gada Prize team!

JohnnyCooper — Mon, 21 Jun 2010 07:03:40 -0400

Obviously: nichrome wire is wrapped around the spooled area.

Re: Recycler! New Gada Prize team!

JohnnyCooper — Mon, 21 Jun 2010 07:02:47 -0400

And as an stl.

Re: Recycler! New Gada Prize team!

JohnnyCooper — Mon, 21 Jun 2010 07:01:43 -0400

Here's an extruder nozzle for this design:
[www.3dcontentcentral.com]

Re: Recycler! New Gada Prize team!

Traumflug — Sun, 20 Jun 2010 13:08:34 -0400

Quote

So using metal for a single worm-gear was found to fail.

Two examples of (obviously) working worm extruders made in metal:

[dki-online.de]
[www.maschinenbau-heilsbronn.de]

(Found in the German RUG)

Re: Recycler! New Gada Prize team!

MarcusWolschon — Sun, 20 Jun 2010 12:42:39 -0400

SebastienBailard Wrote:

> Please don't pick fights with people, Marcus. :)

Well, I just haven´t seen any designs and
would like to build, evaluate and improve one. ;)
The´s a growing bag of plastic. Sorted by material and color
and it´s waiting to be recycled one day.

After I found starch-based bioplastics inadequate
(extreme shrinking, days of drying time) I have nothing
to concentrate on next. ;)

Re: Recycler! New Gada Prize team!

SebastienBailard — Sun, 20 Jun 2010 12:36:26 -0400

I've been doing a lot of plastic machining lately. I've noticed that I'm producing an enormous amount of fine grit ABS powder by buzzing a 1/2" four flute end mill @ ~4000rpm, and using a feedrate of around 3inches a minute.

Ah, but you've got a well-defined block of plastic clutched in a vise. Now imagine feeding irregularly shaped pieces of plastic into it via a chute, or inverting it as if it was a garbage disposal.

Which might work.

So using metal for a single worm-gear was found
to fail. Who is actually up for designing something
that may perform better instead of listening just
commenting?
Better yet, who here actually started working on something?

Please don't pick fights with people, Marcus. :)

Re: Recycler! New Gada Prize team!

MarcusWolschon — Sun, 20 Jun 2010 06:46:44 -0400

JohnnyCooper Wrote:
-------------------------------------------------------
> Real machines use a worm gear style auger. I see
> no reason why this isn't achievable.

With just a worm-gear feeding into a hot-end
it was already established in practical tests
that the worm-gear heats up too much, thus
melting the powder and clogging up the thing.

So using metal for a single worm-gear was found
to fail. Who is actually up for designing something
that may perform better instead of listening just
commenting?
Better yet, who here actually started working on something?

Re: Recycler! New Gada Prize team!

JohnnyCooper — Sun, 20 Jun 2010 06:08:24 -0400

Re: Recycler! New Gada Prize team!

SebastienBailard — Sat, 19 Jun 2010 10:37:27 -0400

Is this thing supposed to be self replicating, easily sourced, or completely open to vitamins?
The recycling part of the toolchain? Anything goes.

Tim from Michigan-RUG mentions that some buddies have achieved good results powdering plastic chunks using a rock tumbler. :D

Re: Recycler! New Gada Prize team!

JohnnyCooper — Sat, 19 Jun 2010 07:31:19 -0400

Is this thing supposed to be self replicating, easily sourced, or completely open to vitamins? Real machines use a worm gear style auger. I see no reason why this isn't achievable.

[www.harborfreight.com]

Re: Recycler! New Gada Prize team!

MarcusWolschon — Sat, 19 Jun 2010 04:38:12 -0400

yellowfrog Wrote:
-------------------------------------------------------
> Would a scaled up nutmeg grinder work? A rotating
> perforated barral with the plastic pressed up
> against the edge so that the plastic is gouged
> rather than shreded.

I don´t think shredding is the problem.
Extruding filament from powder without trapped air,
with consistent diameter and shape and
without the feeding-mechanism clogging up
due to molten plastic is.

Re: Recycler! New Gada Prize team!

yellowfrog — Tue, 15 Jun 2010 18:19:01 -0400

Would a scaled up nutmeg grinder work? A rotating perforated barral with the plastic pressed up against the edge so that the plastic is gouged rather than shreded.

Re: Recycler! New Gada Prize team!

tesla893 — Thu, 20 May 2010 21:36:32 -0400

I am really interested in getting involved with this. Once I have something valuable to contribute I will post it up.

Re: Recycler! New Gada Prize team!

rocket_scientist — Wed, 24 Mar 2010 17:12:53 -0400

I added a comment to pump based extruders like that. If you have a piston (better be steel in this case for the forces exerted) that has a port on the top side that opens when the piston is fully drawn back. Then it is easy to let pellets, granules, or chunks fall by gravity feed into the piston. Then as you force the piston forward it seals the port and starts compressing the plastic. If the other end is heated and has 3 mm orifice, it should produce filament in pulses. I seem to remember that ABS degrades a bit with each heating, so the heater should be kept lower than extruder temperatures and higher pressure in the piston used instead to meld all the particles together. A cam shaft or other set of variable linkages should be used to move the piston fast when it is withdrawing, pause for a moment to fill at the end of the back stroke, fast to begin compressing, then go to greatly slowed down with more pressure as it nears full compression. The whole cycle probably needs to go slowly so the plastic has more time to 'ooze' into filament form.

Mike

Re: Recycler! New Gada Prize team!

Prober — Wed, 24 Mar 2010 11:57:19 -0400

>>>What about using a meat grinder? Something that worked in progressive stages, so that large objects to be recycled and something like a tree shredder cuts them down to smallish chunks.<<<<

I was thinking along the same lines as you with the meat grinder along with the reuse of a few other kitchen tools. I put some time into the idea of using a "dumpling pan" and further a "pasta maker". [probersideas.blogspot.com].

>>Attacking it with a milling bit gives fine powder of course.<<<

I ruled this out a long time ago. KISS, this is the key IMHO >>>>The problem with cutting HDPE is it is one of those plastics that gets stronger when you stretch it until it is incredibly strong and very very thin. <<<

Use as a starting point various temps, within progressive stages to reshape and reuse the plastics for infill.

The device would operate kinda like how they crush cars down to a chunk. For our purposes, the plunger will push the plastic into an extruder to “reform” the plastic into tootsie roll size, or the preferred filament size rewound into a spindle.

If I had the time I would build it:?

Re: Recycler! New Gada Prize team!

Benbo — Sun, 21 Mar 2010 12:23:36 -0400

Polymorph. 20 bucks got me a kilo of the stuff. You'd need a funnel with an agitator though, to keep it moving to the melter. It's the same price per lb as the white ABS from makerbot.

Re: Recycler! New Gada Prize team!

Demented Chihuahua — Thu, 18 Mar 2010 20:55:37 -0400

[www.youtube.com]

Re: Recycler! New Gada Prize team!

rocket_scientist — Sun, 07 Mar 2010 01:40:33 -0500

Anybody have a 3D model of that that we can print out? :)

Re: Recycler! New Gada Prize team!

aka47 — Sat, 06 Mar 2010 18:52:34 -0500

Wow that is cool

Re: Recycler! New Gada Prize team!

VDX — Sat, 06 Mar 2010 14:17:20 -0500

... here is a multi-shredder shown 'in detail': Monster-Shredder (:P)

Re: Recycler! New Gada Prize team!

aka47 — Fri, 05 Mar 2010 22:38:06 -0500

There is a RepRap oriented group at Delft Technical College in the Netherlands doing some work on this.

[reprapdelft.wordpress.com]

They aparently have a plastics shredder on campus. I'd love to know what the blade setup is...........