Just came across this video and transcript of a homemade granule extruder:

[web4deb.blogspot.com]

The builder is using it for making HDPE strips for aquaponics growing media, but to quote the first comment on that page: "You should turn the plastic into a filament so you can use on a 3D printer like a RepRap or MakerBot. "

It seems like it would only require replacing the die.

I really don't know much about granule extruders, but seeing the video was encouraging!

(Not sure where in the forum to post this, feel free to move)

WOW. that looks like several step in the right direction!

I did not get a clear view of the virgin HDPE pellets he was using, but I think that sending milk bottle sides through the paper shredder multiple times would get something close enough.

I could not tell of the auger was made from a meat grinder or wood boring bit set into a custom diameter match aluminum chamber block. It would be nice to see some drawing of this to see what materials he started with and how they were machined. We don't need the waffle pattern on flat strips so that complication can be avoided. Cooling air once the filament has been extruded sounds good. I think he waited until the the filament had been pulled and embossed before using forced air cooling. I also wonder about running cold water through the pinch rollers to hard set the plastic and keep it from sticking.

While a bicycle gear chain is a cheap and easy way to reduce speed and gain lots of torque, if you don't already have a broken bike with perfect power train laying around there may be some other, less Rube Goldberg approach might be recommended. We are already buying lots of pulleys and cogged belts from mcmaster-car, they also sell sprockets and chains for high torque speed reduction. Similar parts are also available internationally from RS. AndyMark also sells both chain and sprocket systems and also gears, gear axles and hubs so that pretty much and speed reduction can be handled. They also sell various strength 12V dc motors and ship internationally to support the FIRST Robotics Challenges. With a powerful CIM motor, H-bridge speed controller, gear reduction box and two temperature controllers for the heater and possibly a second, smaller motor pulling the extruded filament as it comes out and uses a strain gauge to regulate the strength of the pull, a second generation bottle to filament extruder could be the size of a microwave!

Mike

Edited to add international links

Edited 1 time(s). Last edit at 12/12/2010 07:47PM by rocket_scientist.

rocket_scientist Wrote:
-------------------------------------------------------
> I did not get a clear view of the virgin HDPE
> pellets he was using, but I think that sending
> milk bottle sides through the paper shredder
> multiple times would get something close enough.
>
> I could not tell of the auger was made from a meat
> grinder or wood boring bit set into a custom
> diameter match aluminum chamber block. It would be
> nice to see some drawing of this to see what
> materials he started with and how they were
> machined. We don't need the waffle pattern on flat
> strips so that complication can be avoided.
> Cooling air once the filament has been extruded
> sounds good. I think he waited until the the
> filament had been pulled and embossed before using
> forced air cooling. I also wonder about running
> cold water through the pinch rollers to hard set
> the plastic and keep it from sticking.

Looks like a standard wood bit.

> While a bicycle gear chain is a cheap and easy
> way to reduce speed and gain lots of torque, if
> you don't already have a broken bike with perfect
> power train laying around there may be some other,
> less Rube Goldberg approach might be recommended.
> We are already buying lots of pulleys and cogged
> belts from mcmaster-car, they also sell sprockets
> and chains for high torque speed reduction.
> AndyMark also sells both chain and sprocket
> systems and also gears, gear axles and hubs so
> that pretty much and speed reduction can be
> handled. They also sell various strength 12V dc
> motors. With a powerful CIM motor, H-bridge speed
> controller, gear reduction box and two temperature
> controllers for the heater and possibly a second,
> smaller motor pulling the extruded filament as it
> comes out and uses a strain gauge to regulate the
> strength of the pull, a second generation bottle
> to filament extruder could be the size of a
> microwave!

Which is fine if you live in North America, but useless outside it. Which is where most of the world is. Sorry America. Any other suppliers that provide the components you're thinking of outside of North America?

Remember: Multiple options, multiple suppliers, world wide coverage. That's what we need for RepRap.

Cefiar, sorry, I do tend to suggest without thoroughly researching. However, you have just been guilty of doing the same. AndyMark supports the FIRST Robotics Challenges, which are international. If you had checked the shipping instructions link on the first page of the website you would have4 found that they ship internationally, and a flexible as to what type or carrier of international shipping you want.

However, you are entirely correct in that for every reference to McMaster-Carr, I should provide the equivalent link to RS, especially since it looks like they ship almost everywhere.

Sebastian, it may just be my poor search-fu today, but I could not find a wiki page to list standard parts suppliers for each region or country so that newcomers could search down the rows to find where they live, then across the columns to find possible places to get studding, cogged belts, sheet plastic, etc. Although it looks like the list could start with Digikey and Mouser for electrical parts and RS for mechanical. As more people from people from outside the US and Western Europe become active, they can add entries for their countries where it might be cheaper, faster, or possibly have local stores where you can shop and ask questions. It would also make it easier for someone like me to pull his fat out of the fire when posting only local links and ignoring the rest of the international partners. Perhaps as this is something that each new convert needs to find early own we place obvious links and sticky notes to it where newcomers just starting to build would look. As we get more than one company's web-page or phone number for each location/type of parts, it will look less like we are trying to endorse specific companies, although I see nothing inherently wrong with endorsing. As long as the reasons (paid sponsor or typically lowest price) are made known.

Mike

Ahh I missed the reference to AndyMark as a supplier. I was under the impression this was just something sold by McMaster-Carr. Apologies for misreading your post.

FWIW: The Melbourne RUG wiki page lists local suppliers in Australia for a lot of stuff, which includes some of the generic places you're used to (like Element14, Mouser, Digikey, RS, etc) who have a presence here.

I urge all the RUG's to actually do the same, regarding suppliers. There's a lot of local resources out there, in most cases cheaper (even if only due to shipping), that only locals know about. It also provides a great reference for non-locals to use when suggesting places someone can find stuff.

Note: HackerSpaces are also a good reference for this sort of thing.

Edited 1 time(s). Last edit at 12/12/2010 07:57PM by Cefiar.

Hey guys I have just created a wiki page for this fantastic extruder. I will try and get in touch with the creator some time soon to see if we can get some close up photos and code for the micro-controller.

I'm deficiently going to have a go at building this myself.

This is my little toy. I don't do any type of reprap work, but will be happy to answer your questions. (found the site because there was a surge of hits from this site linked to my video.

Send me a private message on you youtube account with your email address in it. I'm usually pretty good about responding to my messages within a day or so.

Thanks

-Rob T.

Cefiar Wrote:
-------------------------------------------------------
> FWIW: The Melbourne RUG wiki page lists local
> suppliers in Australia for a lot of stuff, which
> includes some of the generic places you're used to
> (like Element14, Mouser, Digikey, RS, etc) who
> have a presence here.
>
> I urge all the RUG's to actually do the same,
> regarding suppliers. There's a lot of local
> resources out there, in most cases cheaper (even
> if only due to shipping), that only locals know
> about. It also provides a great reference for
> non-locals to use when suggesting places someone
> can find stuff.


EXACTLY what I was trying to suggest! A global list of local resources so that beginners can get a head start. Plus, the local suppliers are risking their investment capitol to have stock and experts on hand. We should try to help support our local people where possible. After all, one of the goals of repraps without boarders is to have globally created designs produced and available locally.

Rob T,
as I was fading in and out of concisousnous napping earlier it occured to me that your design would expand well into something I was thinking will be required for long range universal fabricators.

In science fiction stories, they have Von Neumann Machines that take in any kind of raw material, process it into building materials, make all the components and then assemble them to produce anything the owner wanted, including another Von Neumann machine. Von Neumann called these universal fabricators to separate them from the idealized computer model that he first called a Von Neumann machine.

To take a step closer to this loft goal, we need our plastic recyclers to take many kinds of source material, preferably plastic wastes, and act on them somewhat differently depending on physical characteristics. For instance, ABS may need to be run through grinder blades or a chipper-shredder as a first stage, whereas the HDPE can be pre-processed from milk bottles to pellets by several runs through a paper shredder or possible a large blender. If we took Rob's design for a ribbon (or filament for reprap) extruder as the second stage and made two or three different first stages to convert waste of several types into the pellets that the second stage needs, then one machine with some switches and controls and different feed hoppers or bolt and swap parts could do several types of plastic.

ABS: Stage 1A using saw blades to break up large/long pieces of ABS pipe into 4x4 or smaller pieces. Stage 1B would be tightly packed counter rotating saw blades to cut it saw dust, giant cheese grater to shave off small pieces, or a small but powerful chipper-shredder. Regardless, the output would sifted to pieces smaller than 5mm

HDPE: Stage one would be a paper shredder that would loop back all the big stuff to be shredded again until everything fits through a 5mm mesh. It may need a pre-shredder stage that cuts whole milk bottles into small, mostly flat pieces.

PLA: Much the same as HDPE.

The output of each stage 1 is a stream of small chunks of 5mm or smaller. These can now be moved by blown air from each plastic specific pellet making stages into the design Rob has. By controlling the speed of the Auger, the temperature of the two melt sections, and the speed of the rollers in the take-up section you could optimize the same filament melt and extrusion section produce 3mm filaments from many types of plastic. To change, you turn a dial on the recycler, it tells the microcontroller which motors to operate and which tables of temperatures and speeds to use, feed construction left over ABS tubing into the initial chunker, and eventually watch black filament winding up on the output spool.

Mike

A few notes:

1. Using 100% recycled plastic leads to structural degradation of the plastic polymer. The plastic may not be anywhere near as useful as new material, so you may need to mix it with some virgin unprocessed material as well.
2. Beware of small amounts of plastic getting into the environment. Unless the whole thing is sealed, I would not recommend using air to blow any particles of plastic around. It would be too easy for plastic to escape into the environment, and eventually ending up floating in the sea. There is already enough plastic there.

Zomboe Wrote:
-------------------------------------------------------
> Just came across this video and transcript of a
> homemade granule extruder:
>
> [web4deb.blogspot.com]
> er-for-growing-media.html
>
> The builder is using it for making HDPE strips for
> aquaponics growing media, but to quote the first
> comment on that page: "You should turn the plastic
> into a filament so you can use on a 3D printer
> like a RepRap or MakerBot. "
>
> It seems like it would only require replacing the
> die.
>
> I really don't know much about granule extruders,
> but seeing the video was encouraging!
>
> (Not sure where in the forum to post this, feel
> free to move)

I enjoyed the video and believe we are on to something here. Some of the parts can be adapted from a pasta extruder per my blog post.
[probersideas.blogspot.com]

I want one if anyone goes for it.

This is seriously inspiring. I'm tempted to build one out of a meat grinder. Would anybody else want to participate in the design of this system? I'm not sure I can do it alone.

Even if you get granules to extrude, how do you make a filament with a consistent enough diameter for use with a 3d printer?

One method I though of is to have kind of a reverse extruder where the hot end feeds into a cooled PTFE lined tube of the desired filament diameter. The tube would then mold the filament to the desired cross section as it cools. With such a setup, it may not be necessary to have a continuous extruder, but instead it could be pulsed. This could be done with a piston that compresses the melt chamber. That may be far more easy to fabricate.

Quote

One method I though of is to have kind of a reverse extruder where the hot end feeds into a cooled PTFE lined tube of the desired filament diameter. The tube would then mold the filament to the desired cross section as it cools. With such a setup, it may not be necessary to have a continuous extruder, but instead it could be pulsed. This could be done with a piston that compresses the melt chamber. That may be far more easy to fabricate.

That's exactly how I want to do it.

Imagine a coil of metal tubing that sits at the exit of the machine. The only problem would be actually starting the filament extrusion process because afterwards you just use an automatic winder to pull the filament through the tube as it cools.

I thing rolling it with two rolls that are shaped rigth to give the filament its final diameter and that are watercooled would yield much better results while also solving the start problem. however they are more difficult to manufacture in the beginning

How could rollers work if the cross-section is circular? The rollers would need a circular hole in them, but then as they rolled, the outside radius of the roller would move faster than the inside radius. This would stretch and deform the filament. I don't see it working well.

does anyone know how they achieve constant cross section with industrial extruders?

Once the extrudate (filament) exits the extruder, it goes through some sizing plates in a water chamber, to cool the extrudate and help it keep it's shape. It is then pulled out of the water bath (at an appropriate rate) using something like a caterpillar puller, to avoid stretching the plastic.

we're going to have to tackle this in our recycling machine.

we're thinking sprung rollers with displacement feed back...

Why did this thread end ?? Did everyone give up on this idea or go somewhere else ??