We’ve seen a lot of homebrew filament extruders, but [Stefan] at CNC Kitchen shows off a commercial desktop filament extruder in his latest video, which you can see below. The 3DEVO extruder is pretty slick but at around $7,000-$8,000 we probably won’t rush out and buy one. We might, though, get some ideas from it for our next attempt to build something similar.
In concept, any machine that creates filament is pretty straightforward. Melt pellets and push them out of a nozzle. Cool the filament and wind it up. Easy, right? But, of course, the problems are all in the details. Die swell, for example, means you can’t just assume the nozzle’s hole size will give you the right size filament.
The 3DEVO machine apparently actually monitors the diameter of the filament and closes the control loop, changing parameters to keep the filament diameter reasonably constant and on target. Looks like it does a pretty good job, too.
[Stefan] is moving towards recycling old prints and we look forward to seeing that video. We’ve seen quite a few of these filament extruders of various levels of success. We’ve also seen some lessons on how to not build one.
The closed-loop mechanism for drawing the filament to final diameter is interesting. The heart of it, of course, is the filament-measuring sensor. I wonder how that works.
It occurs to me that you might be able to create a sensor of this kind by repurposing a linear optical sensor from a scrapped scanner of fax machine. You could use an LED and lens to illuminate the filament and cast an image in the optical sensor.
That’s exactly how it works.. the same method is used in draw towers for optical fiber.
Apparently, it isn’t that simple. Not sure if it was here or somewhere else, but I remember reading about someone who tried that, and they discovered it required a fair bit of processing to get an accurate result out of the sensor, and it was complicated even further when dealing with translucent and transparent filaments.
I think they ended up just going with a mechanical sensor and getting excellent results out of that with little effort. The only downside would be wear, but I mean…I can’t see that being much of a problem, for a hobbyist’s usage. Optical obviously works, because it’s used, but I’d personally opt for a mechanical sensor, I think.
There is a 1D CCD sensor.
a single point?
A line.
@Al Williams said: “Machine Extrudes Filament” Yawn… We need: “Filament Extrudes Machine”.
oh. you already have such machine? cool! can you show us?
I would think you could pull cold filament through a series of dies to get to a specific diameter and circular cross section.
I don’t think cold pla is ductile enough for that
Then maybe get it above its glass transition temperature (60-90C depending on formulation).
Something similar but instead of pulling through dies, use a series of steel blades to shave it to size.
Or maybe something like an old-fashioned crank-driven pencil sharpener, made to produce a 1.75mm “point” and which would allow the filament to pass all the way through without obstruction. (Whereas with a pencil sharpener it is inserted and removed at one end.)
Take a look at a dowel making machine – that’s exactly how they work.
Many years ago, when we had a problem with bad filament supplies at Ultimaker. We tested the filament for being to thick by pulling it trough a 3.1mm hole in a 8mm thick steel plate. It would get stuck if it was too thick, “shaving it down” with it didn’t work.
I suspect “shaving it down” would require a particular geometry, not just a hole in a plate. Something closer to a tube with a sharpened edge at the opening, perhaps spinning.
After just babysitting a 12-hour print that jammed every hour or so because of the scramble-wound spool (like the first one presented here), I’m very interested in finding reliable suppliers of nicely-wound filament. Stefan mentioned Prusa as being good, but it’s double the price of the (usually) “good” stuff, triple the price of the “Amazon special” Sadly, reviews don’t often mention spooling quality.
Any known-reliable brands?
I don’t know about brand issues, but this video saved a 20 hr print in the middle of the job.
https://www.youtube.com/watch?v=uf66_3bzIgc
HTH
Ha! Thanks for that. Intellectually I knew that, and thought I’ve been careful about unpacking and loading, but I clearly screwed up this one.
Unwound a few turns as directed, found the tangle, and all is good now (I think, halfway through a 3.5-hr print)
Glad there was some useful information there. :)
My spool got loose so I rewound it with some plywood washers, threaded rod, and a drill. I tensioned it by running it through some Denim I sat on.
In my case the spool rocked on its rod as it unwound, I gave some thought to a bearing mounted spool with perhaps a rubber flap to keep a little friction on rhe spool.
Fillamentum but they are even pricier than Prusa :D
Sunlu and eSun are always a good choice.
E suns abs has always done me right and ive never had an issue with the spooling. They have a deal on amazon for 5 rolls at about 70$
All are reliable. The fault lies not in our filament suppliers but in us. Proper handling of spools prevents tangling. Never let the free end of the filament loose. Don’t use spool holders with a vertical axis. When you take filament off the machine, insert the free end of the filament into the holes in the flanges of the spool. The final step is to use a spool holder that prevents filament from jumping over the flanges (fresh PLA spools are the worst for this). Filament holders like that have rollers that contact the edges of the flanges, thus preventing jump-offs.
https://4.bp.blogspot.com/-X984BHia1W4/WhIFfNNTavI/AAAAAAAAG-A/QAq75QT8lF0bjHELXIYjh_6B3PntIfbzwCPcBGAYYCw/s1600/11190008.jpg
I’ve found Filaments.CA and ColorFabb to be very consistent re: spool winding and diameter.
I’ve used eSUN lots and never had a single tangle. Prusia is awesome tho
I was just lucky enough to have a guy come to my recycling party who had a pellet extruder that connected directly to the nozzle on his 3D printer. It printed amazingly smooth and seems like it gets rid of the problems with creating filament? Like no worries about spooling and storing. PLUS we then ground up our own Plastic pellets from garbage and could make 100% 3D prints! I made a little quick video to show the process!
https://youtu.be/iCuet5gdE4c