Desktop Factory Competition

I just found out about this.

[desktopfactory2012.istart.org]

The challenge is to create an inexpensive machine that produces filament from pellets.

I searched this forum, and only found two passing references to it; one in French, another in German. I just thought the wider RepRap community might be interested.

-Matt

It's cool in theory, but I don't really see why I would want to make my own filament, unless it makes it easier or cheaper to make small batches of different colors. That would depend on being able to get pellets in small quantity. Or if there was a way to make my own colors with pigments or easily calculated recipes for mixing colored pellets. If I could start with a large quantity of natural pellets, and extrude 15m of a particular color for a project rather than buying 1KG of it, that could be worth it.

I imagine it would take at least as much knowledge and practice to create consistent quality filament as it already does to make quality prints. The pellets are cheaper than spooled filament, but may be more expensive when you add in equipement, time and effort.

How does filament colored on the surface with a marker compare to pigmented filament? If I made a rig that would wind filament from one spool to another, passing between a couple or marker tips or through a sponge soaked in red ink, how does that compare to just using red filament?

Good luck with that one. At $250, they have made sure the money will never be paid out.

Plastic filament like natural ABS colored with a marker will come out as a very pale pastel color of the marker color. There is several renditions of this on Thingiverse. Like Filament Marker Colorizer

Making the filament with the right diameter, roundness, and right tolerance is something even experience extruders stuggle with. On top of that, the resin must be dried, loaded, metered, plastisized, and finally extruded. The torqe to do all of those things places any motor and controller outside the $250 range without any heaters, the barrel, or the extrusion screw. The extrusion screws are very complex and expensive to machine.

Or you could just make a heated extruder with a very poor extrusion properties, in which case you will get a pulsating filament with rapidly varying diameters. It would make prints look like wicker baskets, maybe not a bad thing for some applications.

But wait... Someone did it already.

Edited 1 time(s). Last edit at 06/11/2012 05:56PM by remondo.

Although you can purchase the PID controller on ebay for less, The PID temp control alone retails for MORE than $250 by itself. There is no plastic dryer, which you absolutely need in order to produce consistant filament diameters. ABS is a very hydroscopic plastic that has got to be dried to eliminate nearly all moisture that is in the normal air. Not just like below 40 % relative humidity - VERY VERY DRY. Normal in line processes use a dual bed dessicant dryer that is heated to approximately 1/2 the temp of the melt temp of the plastic to be processed. The dessicant combined with the heat remove the moisture. If you don't remove the moisture, you will boil it inside the plastic when you are trying to extrude the plastic into filament. The filament diameter will be all over the place, the profile of the extrusion will also be bumpy.

Although you can extruder plastic even with moisture in it, the quality of your prints will never be high quality. Also, they way in which it is extruded will not produce a round filament. It will be oblong, otherwise most extruders used in RepRap will have problems with it.

I can go to an industrial auction and purchase a small used industrial extruder for below $250, but I don't think that would count either.

That said, I do think they are making progress and it is a goood project. I am glad they switched from using HDPE (that no one uses for open source 3d Printing anymore), to ABS. I don't know how they went from natural ABS to black printed parts. ABS doesn't color change when extruded. Maybe they used ABS they extuded before?

Best of luck to them. Although I doubt they will be able to produce extruders under $250, I think it will be able to help lower the cost of extruded filament - a very good thing.

Beekeeper Wrote:
-------------------------------------------------------
> Although you can purchase the PID controller on
> ebay for less, The PID temp control alone retails
> for MORE than $250 by itself.

How about making a PID temp control using a thermistor (or thermocouple if you wish), a microcontroller and a transistor/triac.
Just like its done in.. euhm.. reprap printers?

Why do the pellets need to be any dryer than the filament we use? I.e. I keep my filament in a room with about 50% humidity and I don't get problems with moisture.

---

[www.hydraraptor.blogspot.com]