What to do with empty spools? Quoi faire avec bobines vides?

[BDan]

Oui, pas besoin de les déchiqueter, faut les réutiliser. Mais il nous faut une ou deux places locales qui produisent et distribuent du filament de bonne qualité. J’ai envie de faire ça et je demande si on peut co-financer l’achat d’une machine décente. On aurait une belle entente et on partagerait les revenus. De la même façon on peut co-financer tout ce dont nous avons besoin collectivement et localement.

[BDan]

I was looking into DIY filament extruders but I find the tolerance varies too much: diameter 1.75 ± 0.2, with perfect parameters ± 0.1, it’s not reliable and it might cause problems in the printers. Also, without a real extruding screw (people use drill bits) you have problems with bubles. If someone will produce local filament for local distribution and reuse those empty spools, it’s gotta be decent quality.

[BDan]

I would like to find a decent machine, no too big, no too expensive, and to crowdfund it with local Makers who would benefit from local and more affordable materials and contribute to better recycling practices. In the Lab where I’m operating (Making), if I have no time to do it, there are members willing to take over tasks like pulling and extruding filaments.

[Pot8oSH3D]

All great ideas! I think that a spool return program would be very popular, especially for partially recycled filament.

That said, I’m backing the Omni Dynamics Strooder Kickstarter campaign and have good reason to expect that the resulting filament will be within the tolerances required by typical 3D printers.

Seems to me that the biggest hurdle standing in the way of small-scale recycled 3D print filament production is the design and production of a machine to mash up plastic parts. I’ve seen a couple of campaigns, none of which light my candle - I’m looking for a low-speed, high-torque shredder. The closest I’ve come to what I’m looking for is this video…

https://www.youtube.com/watch?v=Nmbzks1RXBM

Here’s a similar design…

https://www.youtube.com/watch?v=B2L7FLYhbp0

…and you can see the problems - It’s heavy and it needs LOTS of power. Personally, I think a hand-cranked design is the way to go - No harm beefing up those biceps - but you still need at least 5 Kilos of fairly tight tolerance steel, which is never going to be cheap to buy or to transport.

One style of design that might be an answer…

https://www.youtube.com/watch?v=aoD92UlKNx0

Now, THAT looks to me like it could be adapted to the purpose without too much difficulty.

Anyone have any other ideas??

Cheers!

AndyL

Pot8oSh3D

[Joseph_Romano]

Why not just get a Blendtech Blender? Haha

[BDan]

Yeah, hand power is sufficient for the purpose, second design is good and I have contacts in the Building for wire cutting, they have all standard plates in stock (still very expensive). I think for most domestic needs a paper shredder able to mash up CDs would do the job for some plastics in the recycling bin and for supports, probably not for bigger failed parts. But for heavy duty local production there are commercial shredders we can find used and in good condition… these things are tough…

[BDan]

Nice!

[BDan]

Il faudrait des projets comme ça partout, localement, dans tous les FabLabs par exemple

[Pot8oSH3D]

Haha! Well, if ya do, make sure you put some water in with the plastic or it’ll melt!

Also, extruders don’t like plastic powder much.

Cheers!

AndyL

[BDan]

Thanks, so you understand the importance of decent pro-level equipment for serious decentralized business… I think DIY-level won’t cut it and it costs the same in materials, time and effort… We can find a good small industrial extruder for about 2K$ and a heavy duty shredder for something like 500$

[3DPrintingBeast]

use a polymer to refrain it into PLA or ABS plastic

[MB3D]

I think it is really difficult to get a crusher for printed parts aswell as a filament extruder. You will have to use so excessively much filament to refinanciate those both items.

I am currently in my finals, but after that i will try to build an extruder made for Prusa or Lulzbot models that uses pellets instead of filament. The advantage is first of all, that pellets are very much cheaper then filament, pellets cost close to 1/2 to 1/3 of filament price.

Then you would also only have to get the crusher, but no filament extruder.

This method would recycle old prints, but this would not account for the spools, unless you know the exact plastic that is used for them, then you can crush the spools too and make pellets out of them.

I don’t think that there is another purpose for the spools beside storing filament and getting recycled into new filament/pellets.

I am not really into material sience, but would heating or cooling the prints make it easier to crush them while still not melting them.

What I mean is, that every thermoplastic (the kind of plastic that can be used for filament) has a so called glass transition temperature called Tg.

This is the temperature at which the plastic starts to get bendable because the stiff molecule structure falls appart. Having some heater cardridges in the crushing disks (like in both videos) that heat the part up to ~55-80°C (more for exotic plastics like polycarbonate) would make crushing easier i think.

With some gearing in front of the crusher it will be much easier to turn it, turning antiproportionally more times on the handle would be no problem if you use your own musclepower instead of a motor.

However this all is still very expensive, even if you just want the raw materials for the machines.

[MB3D]

You know, that PLA and ABS as well as the spools (most times PC => Polycarbonate) are polymers ?

[BDan]

Hi pomaer! we tried the idea of using pellets in a printer instead of filament few years ago in our lab. It was a monster DIY printer intended to be the next home appliance… We quickly realized that moving a hopper and all the weight around was not an option. We also realized that pellets bring problems with air and filament is still the best way to go. It’s light and the print head can muve faster, and the printer will endure less stress from the head changing direction, and it’s consistant. Then we decided to put a hopper and an extruder in the top back side of the printer and the filament produced would be uneven and cause many problems, and that it had to be dried before we feed into the printing head. Our conclusion was that instead of trying to build a do-it-all thing that does nothing right, it’s better to do things with specific jobs as good as possible. Often times, keeping things simple and sturdy is your best option. It’s still possible to have a crusher and an extruder dirrctly integrated into a home appliance sized 3D printer. It would look something like a stove. But there are so many parameters to watch out for… Unless it’s a super reliable closed loop feedback system that monitorizes and decides for best parameter by it self, most users are not Makers and will lose patience… now for the heating of the shredder blades, I think it’s better to freeze the plastic before you mash it, it becomes more brittle and snaps easyer when it’s frosen hard. I think heating it up even a bit will just make it bendy-er

[MB3D]

Freezing could have a quite positive effect on the crushing of parts. Did your pellet extruder contain a filter and did you use an extruderscrew or just an auger one? One of the most important features that DIY pellet extruders are missing is a real extruder screw that compresses the pellets by getting smaller (the space where the pellets are gets smaller). I thought about a design for a printer, that doesn’t move the printhead, I’ll explain that later. -Marius

[Pot8oSH3D]

This is all interesting stuff. I think that there are many challenges here and it’s best to separate out the issues. Firstly, I think we need to decouple shredding from extruding.

Shredding has its advantages, which are mainly environmental, rather than financial. Realistically, I think a semi-centralised shredding function is most practical.

Extruding is financially very attractive. As Marius says, granulated plastic is cheaper than filament, except that the actual difference in cost is enormous. I heard that the World market for filament is less than 100 Tonnes. The market for granulated plastic is in the Millions of Tonnes per year so the potential difference is very high - think 1-2 Cents per kilo for granulated plastic. Now THAT concentrates the mind!

There are one or two granule-fed print heads surfacing. TBH, I think it’s only a matter of time before the technical challenges are met. Perhaps it’s been done already.

cheers,

AndyL

Pot8oSh3D

[Odense3DPrint]

most of those machines don’t have a closed loop control of the filament… What they all lack mostly are a sensor that measures the filament width and then adjusts according to that.

Modular Filament Extruder by diegotrap - Thingiverse is close to cheap and good enough, all its missing is this one Filament Width Sensor - Prototype 2 by flipper - Thingiverse

and then you simply adjust the speed of the puller so the diameter matches… it will take a bit for the width to be stable, but once you reach that stage you simple cut the filament and the first bit you can cut in small bits and melt them again

going to build it over and after summer…

[BDan]

You’re right, we used a drill bit for the proof of concept and we should have tried with a real screw. We thought the best way would be twin screws heated by induction to keep the temp stable. There are some neatly designed twin screws that take care of air bubbles, evenly mix in pigments and other stuff like carbon microfiber or nanotubes, etc… But then again, extruding the plastic is not enough. Pulling, stretching and cooling is a fine balance of parameters for best results with each plastic. That’s for filament usung 3D printers, I can’t wait to see your design… Cheers!

[MB3D]

@Pot8oSh3D @BDan I thought about anot extruder design somewhat similar to the STACKER 3d printer. You can change the stacker-hotends depending on the material that you want. There would be three heat zones in the extruder which is will explain soon. Sadly I wasn’t at the PC since todays morning morning. -Marius

[MB3D]

Here is the explanation. I hope everything is readable.

The following is the text on the picture on the left side:

(1) Sliders for extruder

(2) ramaining panel for mounting the extruder

(1) “feed”-area where pellets get inserted into the screw; Temp -> 25°C (no heatsource in this area)

(2)“compression”-area where the pellets get heated to glass transision temperature and get compressed to form an air-free paste, the screw’s geometry is made for this; Temp -> 60-100°C (depending on material)

(3) “extrusion area” selfexplaining; Temp -> 180-300°C (depending on material)

//The small brown connectors between the bigger blocks that determin (1) to (3) are heatbreaks just like in nearly every hotend to ensure, that the possible 300°C from the hotend do not get up to the “feed” area. The screw is obviously out of metal and therefore conducts heat very good.

-Marius