It was time for a new plastic extruder head with better resolution, more measurable deposition and could compensate for slight changes in filament diameter without jamming. I modified an extruder design that Matt Laberge had uploaded and printed it with my old extruder. The new extruder uses 1.75mm ABS plastic filament, so it is much easier to work with a melt down than 3mm. It is acuated by a geard NEMA 17 stepper motor and also has a spring loaded idler wheel to account for slight changes in filament diameter. I also am using a .35mm nozzle for higher resolution with a .25mm layer height. The old extruder used a .50mm nozzle with .50mm layer height so I have effectively doubled the resolution. The new extruder is also around a quarter the size of the old one.
New Extruder Being Printed by the Old one
Brass Threaded Thermoplastic Inserts last longer than tapping the plastic
Old Extruder next to the New Extruder
New Extruder mounted
As it appears, there is no feedback sensor on this new extruder. Have you noticed any “quality” issues with the feed now being open-loop?
No problems, the motor has not skipped a single step.
I’ve been very curious for quite a while now…why do these machines use filament rather than (10X cheaper from what I could tell) pellets? I’m still in the planning stages.
Filament is much easier to work with then pellets. The design of the extruder is much simpler and easier to maintain then a screw based extruder for pellets. But, yes you are right that pellets are much cheaper, and really a pellet extruder would be ideal for this reason.
If one can make a pellet feeding and extruding nozzle, then I think pellets are possible too. BTW Bryan I am considering to start this project too, any advice and usefull links?