easier filament access to the extruder
I've found that when loading filament, the last couple of centimeters (just past, or within the Boden fitting) are the hardest part of the process. It's very hard to push the filament from 80 centimeters away past the point where it seems to be stuck. I also dread the thought of trying to repeat that process with TPU. So I thought I'd try this approach. Remove the Bowden tube from the fitting, remove the fitting itself, cut off approx. 2.5 cm of tubing. That leaves space to feed the filament into the extruder by hand (i.e., thumb and finger). It also provides direct access to the extruder for flexible filaments. See picture.
I'm trying to imagine what the downside of this approach might be. Maybe brittle filaments could be snapped at the point that the filament exits from the tube during fast or large movements of the extruder? I've started a large (in terms of print surface coverage) print to see what happens. If the filament does break, my first step will be to expand the endpoint of the tube into a funnel so that it doesn't have a sharp edge. If that doesn't work, I'll cut the tubing back further and, again, expand the tube.
What do you think? Am I missing a looming problem?
Thanks,
Ken
RE: easier filament access to the extruder
So far so good.
When I removed the filament I did see some filament powder at the top of the opening where the Boden connector would normally be. I may need to figure out a way to screw something in there that is more accommodating of plastic filament.
RE: easier filament access to the extruder
Here's what I've learned from the process.
First I designed a collar to fit in the Bowden connector and accept a small length of Bowden tube (6 mm or so).
That solved the problem of controlling the path of filament into the extruder to limit wear on the filament.
That exposed an entirely different problem. It turns out that the Bowden tube is critical to supporting the Nextruder cable bundle. I just assumed that that job was the responsibility of the "flexible plate". But the plate is too flexible in the Y direction and will bend forward right above the extruder, allowing the shortened Bowden tube to slide along the filament (with each retraction move) until it's resting on the top edge of the collar. The plate can bend forward (and retain the bend) far enough to interfere with tool exchanges.
That led me to design a retainer clip - mounted to the Nextruder - that keeps the plate from bending forward.
It's outlined in yellow in the picture so it's easier to discern against the black components.
So far it seems to be working fine.
The next step will be to install a filament mount above the XL and use it to hold flexible filament spools that can be fed down and directly into each extruder.