Briefcase sized, portable plastic grinder/filament extruder/spooler

I've been working nearly four years (off and on) on an improved design of Ben's Briefcase 3D Printer. One of my intentions was to include (or design separately) a folding filament making station. (about the same size) I've since abandoned the idea after finding out a few problems.

1. Assembly - From the motor to the hopper to the feed screw to the heating chamber and finally the extruder head, It all needs to be tight fitting and of solid construction. Once everything is assembled, it's would need to stay assembled. Otherwise you'd need to carry along tools (large tools) to put the parts back together. You don't want to have to assemble and disassemble it everywhere you went. It would take too long.

2. Size - You can leave everything assembled and just make it so that your winding spool folds down and take off your hopper, but your overall length is still determined by the length of the unit itself. This would just be making a box around it with a handle on top and would be very awkward to carry. (You may just put a carry handle on the top of the Filabot Wee.)

3. Convenience - Would it really be all that useful to make it portable? To even start making the filament you'd want to have a collection of bottles saved up. It seems easier to transport a few bottles to a local MakerSpace rather than lugging around a large extruder. Even still, the bottle need to be prepared ahead of time. This means removing the stickers and separating the caps and the tamper proof ring from the bottle (Usually a different type of plastic). The bottles would probably have to be boiled first as well.

It's nice to be able to pack it away when you're not using it, all nice and neat like, though. But that's no different than my sewing machine having a cover with a handle on it.

Even if you wanted to make it so that you disassembled everything. Ben would only be designing a toolbox to carry the parts and tools in. I'm sure it would be an awesome box, but where is the "hack"?

I'd love to see this project too. Maybe Ben can find a solution to the troubles I've found that has kept me from making it.

I've been working nearly four years (off and on) on an improved design of Ben's Briefcase 3D Printer. One of my intentions was to include (or design separately) a folding filament making station. (about the same size) I've since abandoned the idea after finding out a few problems.

1. Assembly - From the motor to the hopper to the feed screw to the heating chamber and finally the extruder head, It all needs to be tight fitting and of solid construction. Once everything is assembled, it's would need to stay assembled. Otherwise you'd need to carry along tools (large tools) to put the parts back together. You don't want to have to assemble and disassemble it everywhere you went. It would take too long.

2. Size - You can leave everything assembled and just make it so that your winding spool folds down and take off your hopper, but your overall length is still determined by the length of the unit itself. This would just be making a box around it with a handle on top and would be very awkward to carry. (You may just put a carry handle on the top of the Filabot Wee.)

3. Convenience - Would it really be all that useful to make it portable? To even start making the filament you'd want to have a collection of bottles saved up. It seems easier to transport a few bottles to a local MakerSpace rather than lugging around a large extruder. Even still, the bottle need to be prepared ahead of time. This means removing the stickers and separating the caps and the tamper proof ring from the bottle (Usually a different type of plastic). The bottles would probably have to be boiled first as well.

It's nice to be able to pack it away when you're not using it, all nice and neat like, though. But that's no different than my sewing machine having a cover with a handle on it.

Even if you wanted to make it so that you disassembled everything. Ben would only be designing a toolbox to carry the parts and tools in. I'm sure it would be an awesome box, but where is the "hack"?

I'd love to see this project too. Maybe Ben can find a solution to the troubles I've found that has kept me from making it.

I agree, it could be difficult, and there are others making extruders.  None that I know of grind, melt, extrude and have a take-up reel, in one compact unit.

Not many maker-Spaces around, much less those with extruders.  How many in your town?  None in mine, and only 3 listed for the entire state of Texas...  Nearest to me is UT Austin and they have 3 different 3D printers listed, no extruders, whatsoever.

Sure, someone has to collect, and clean the jugs and/or bags, let them dry and run them through a heavy-duty shredder.  It's called supplies and preparation.  Can't think of a single construction project that doesn't need supplies and preparation.

Why does it need a bunch of heavy tools?  Why not have interchangeable heads, for different plastics?  For every problem, there is a solution.  It may not be an obvious solution, but where there's a will, there is a way.

Where's the 'hack'...?  How about a completely portable 3D Printing Factory, capable of being carry-on luggage, for air travel?  Isn't that worthy enough?  I know there's a need for it, and I know people that travel internationally, on educational projects, even school trips...  Why not a complete system capable of going to Central America, the Middle East, Africa, India, Asia, or even the next city over, to make 3D prosthetics, for people that need them?

How about starting off with a two-step process ?

First step to create a uniform stock material from the recyclables. Second step to extrude from that newly formed stock material into a spool of filament.

Something similar to the concept of glue-gun sticks, with the intermediate stock being made using a basic melt and mould type process.

IMHO, that requires an unnecessary melt, more energy, time, and an additional molding process.  Might as well make pellets, at that point.  That's really the purpose of using shredded stock, then being able to combine the final grinder, melt and extrusion in one portable unit.  The grinder wouldn't be necessary, if all shredders produced the same size particles.  However, there are other ways to do it.  Using pre-shredded stock and a decent sized fold-out hopper, then keeping the thing fed, producing the filament should be relatively easy.  At the same time, it may be possible to use available pellets (I've found them in bags and drums at salvage yards, from time to time), as well as tail-ends from other reels, since they would also go through the grinder.

Maybe temps could be controlled with a temperature sensor and PWM power supply?

Suppose the whole case-top opens, like a doctors' bag, to be the feed hopper, then that ends in a grinder/auger, at one bottom corner, which feeds the heater-head/extruder assy., and out, past cooling fans, to the take-up reel.  Might be able to include room for a selection of heads, for common types of plastics, so as not to need cleaning.  People leave old glue-sticks in the gun, and just feed a new one in, as needed, why not with the extruder, and even the printer, as well? 

Take-up reel could fit on a motorized, fold-out arm, like a movie projector.  Store one or more reels, depending on size, inside the hopper, when closing down for transport, or storage.  Make all reels so they are interchangable, from take-up, to being used in the printer.

Should be a relatively easy experimental process to figure the extrusion speed for consistent filament, and use a stepper motor at a relatively controlled tension.  Once temperatures and speeds are determined, lock in the settings, so they can be selected by a simple controller, similar to the one for the existing printer.

Out of all of it, the hopper and take-up reels would require the most space.  Combining reel storage and an empty hopper is almost a no-brainer.  Maybe arrive with several spools full of the expected plastic filament, and be using them, while extruding more?  At least it shows a continuity, but still encourages recycling the plastic, rather than having the person doing the printing supply everything.  Maybe they show up with the twin carry-ons, and set up the extruder, then, once it's filling an empty reel, take a pre-filled reel, and start the print.  As parts come off the printer for cleanup and assembly, the whole process continues.  Once the last piece is printed, the extrusion continues until is has caught up with restocking.

Never having done, or personally observed either, I don't really know which process is faster, but, from what I gather, the printing is faster using filament, than extruding produces it.  The extruder would need to be more robust, in order to provide filament for multiple 3D printers, for classes, but by having a uniform and ready means to supply filament, the students get more bang for the buck, out of the classes, as well.

Doesn't the shredder/grinder/auger approach have a tendency to trap a lot of air (and perhaps wash water) in the recycled material as it gets pushed toward the heating chamber for the extrusion process ? A lot will likely be pushed back through the auger under initial compression but some will likely get trapped and pushed into the heating chamber and exit through the extrusion nozzle as a bubble in the filament. (may be an idea to detect for this in the overall design anyway ?)

For 3D printing to work successfully then to me it looks like the quality of the filament has to be pretty high. If there is an air (or water) bubble in the filament then not only is the filament likely to break it is going to result in an uneven layer being printed. With this in mind, a 'melting pot' approach may avoid the need for pre-shredding and help remove any air and water and allow for the skimming off of any floating contaminants (label residue) prior to extrusion. It does however use up energy for the heating as you suggest.

I suspect that part of the 'fun of the design' will be figuring out feed rates at each stage and fine tuning motor speeds/temperatures to keep the production flowing without interruption to the filament.

I know that my suggestion for a two part approach was less than ideal, however I was also aware that an overly complex project may not get featured on the show whereas a modular one might. Pellets sounds like a good halfway point to me - build a machine that can extrude from recycled pellets, then build a machine that can create pellets from shredding recyclables. Line them up in front of the 3D printer and then you have your portable factory which can be further refined.

Shouldn't be any water in the system, other than possibly vapor from any absorbed by the plastics.  Some plastics absorb and/or are more permeable than others.

How about a hopper to feed-auger/grinder, into a small melting chamber, then a second auger extruding off the bottom, so the extruder only gets liquified plastic?  Still needs to be a continuous process, once started, so the hopper needs a capacity large enough to allow for normal human activity and behavior.

Something like one of those coffee-grinder to fresh coffee makers.  where the feed stock is in a hopper, then goes through a grinder and into the rest of the process.

For that matter, w/PWM heat control, maybe insulate an automatic-drip coffee-maker heating element/tube, as the melting area, prior to extrusion?  Or wrap a heating element around a piece of pipe and insulate that, for the melt chamber?  Pot sits on top, like a coffee caraffe', preheating and melting, then auger feeds through the heat-tube, pushing out through the metered orifice, for the final filament size?  Might be able to insulate and convert one of those single-cup size ADC coffee makers?  Extruder auger would need a thermal control switch, as well, preventing it from operating below some suitable temperature.

Maybe, initially, have a designated plastic, and make only one kind of filament, such as collecting and cleaning only plastic milk-jugs, is the source?

Excuse the MS Paint, it's what I have and I'm no artist, by a long shot...

I was thinking of small amounts of water left over from cleaning the plastic. If it goes into a hot melt though then this should quickly boil off as the melt point of HDPE appears to be around 250F, well above the boiling point of water at 212F.

I thought about feeding liquid plastic into the auger as well. May need to have this at a slightly lower temperature (250F-300F) so that the plastic is still gooey at this stage rather than fully liquid so as then the auger doesn't have to be so liquid tight. Alternatively consider a near vertical auger so that leakage is less of an issue. Then the extruder heater can raise it up to the 350F+ required for extrusion. Another bonus is that if the plastic is in a liquid state in the auger then less torque will be required to turn the auger. The downside is if the liquid plastic is allowed to cool in the auger then it will require to be heated up to 250F to get things turning/flowing again.

High temperature glue guns appear to operate at around 380F so could potentially be used for the final extrusion heater and will have thermostatic controls built in.

Designated plastic initially sounds like a good idea to me as there is less chance of human error in identifying specific plastic types.