You might not think to use the word “rigid” to describe most 3D-printer filaments, but most plastic filaments are actually pretty stiff over a short length, stiff enough to be pushed into an extruder. Try the same thing with a softer plastic like TPE, though, and you might find yourself looking at this modified Bowden drive for elastomeric filaments.
The idea behind the Bowden drive favored by some 3D-printer designers is simple: clamp the filament between a motor-driven wheel and an idler to push it up a pipe into the hot end of the extruder. But with TPE and similar elastomeric filaments, [Tech2C] found that the Bowden drive on his Hypercube printer was causing jams and under-extrusion artifacts in finished prints. A careful analysis of the stock drive showed a few weaknesses, such as how much of the filament is not supported on the output side of the wheel. [Tech2C] reworked the drive to close that gap and also to move the output tube opening closer to the drive. The stock drive wheel was also replaced with a smaller diameter wheel with more aggressive knurling. Bolted to the stepper, the new drive gave remarkably improved results – a TPE vase was almost flawless with the new drive, while the old drive had blobs and artifacts galore. And a retraction test print showed no stringing at all with PLA, meaning the new drive isn’t just good for the soft stuff.
All in all, a great upgrade for this versatile and hackable little printer. We’ve seen the Hypercube before, of course – this bed height probe using SMD resistors as strain gauges connects to the other end of the Bowden drive.
At first I wondered what was the advantage of the spool holder pictured next to the drive in the banner photo.
Then, I realized, it’s a chess piece!
The link for the modified bowden drive is the same as the one for the original Hypercube 3D printer, and there is not an obvious link to the modified bowden drive.
His original hypercube 3d printer repo already has updated parts.
Model your drive filament path at the OD of your PTFE tube, and then you can run the PTFE tubing all the way to the drive roller.
https://youtu.be/P7qFqPJesd4
I wonder if this meaningfully improves on the prior art like https://www.thingiverse.com/thing:2599755.
it does use a smaller bearing, which allows it to have a smaller gap.
Wow! That’s a whole bunch of extruder designs derived from my original simple bowden extruder design. I’m happy to see it being used by so many printer enthusiasts. Thanks a lot for sharing and many thanks @tech2c for mentioning my original design. 😉👍