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  1. That's an interesting point. I wonder whether it's possible to use that connection to crudely control something (ie. no feedback), such as using a relay to switch on a cutting blade.
  2. That would be the ideal solution. It could either trim off the tails, or cut through the filament itself (there tends to be a deformed section about 12mm long, which has been melted and solidified before the tail, which is normally slightly wider than the filament). You'd probably be best off having a blade which cuts the tail as soon as it exits the hotend, to avoid having tail remnants in the bowdens. That way you don't need to find a way of removing the cut off tails, as there shouldn't be any. Perhaps a disk which can spin, with a hole drilled in it. The filament normally passes through th
  3. We've been working on a similar concept at Open Bionics. The aim is to prevent the filament stripping if it jams, so we avoided using metal gears in tandem. Our first design used gears that were too small, and skipped before it could extrude. The metal gears here were inspired by yours - but it worked much better without! The different diameters of the metal and ninjaflex gears mean you have to be careful how you design the gears, as you need the perimeter moving at the same rate. I think you got away with it because your two gears on the stepper have the same diameter - ours didn't! Note
  4. We've got ninjaflex and PLA printing well out of 2 nozzles, as per my post in the Flex3 thread, linked below. This is usable, though not totally reliable (though often bizarre non-recurring errors, such as z-shifts mid way through a 20 hour print...). We've also got a Diamond Nozzle (discussed below). For now, the yield rates are unsatisfactory, so multi material is going on the back-burner. We'll look into The Palette, or a 3mm Diamond Nozzle, when released. Interchangeable heads plus diamond nozzle would be fantastic (6 filaments!) - but we need to get the individual components working well
  5. At Open Bionics, we've been experimenting with automatically changing the filament in the hotend. The goal was a solution which could accept as many different filaments as we could control off the board, with only one hotend. In theory it wouldn't require complicated parts, and could be highly expandable. The idea was to withdraw the current filament from the hotend, and push another one in, extrude that, and repeat. We used a "tight" demultiplexing part, where the filaments were fully enclosed by bowden tube for as much time as possible. This part screwed onto the top of the U2 head. The
  6. At Open Bionics, we've managed to crack the second filament issue. We started with the Flex3drive U2 head, and with a bit of tweaking managed Ninjaflex out of the Flex3drive, and PLA out of the bowden. Firstly, we redesigned the coupler between the stepper and flexible shaft, as it was skipping badly. We stuck a bit of bowden above the nozzle to stop the filament bulging out the gap (circled, A). The flex3drive head is slightly taller than the U2 head, which meant it hit the casing when the head homed - so we had to fudge the endstop a bit. The trick to adding the second filament is to rot
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