Flexable extruder drive

This guy has been working on a flexible extruder drive for an ender3 printer which has the stepper left on the frame and the extruder mounted on the gantry, the best of both worlds. It would reduce the weight on the gantry which would be good but I wondered if there would be some lag time and “slip” in the drive that would be a problem. He hasn’t finished it yet do to some “technical” problems AKA he screwed it up.

He has many different/weird upgrade videos and also one on a foldable printer that someone here was asking about.

Ive always wondered why remote drives havent become more of a thing.

@Dr.Marvin & @Loosenut

I would like to see what is done about keeping the internal cable from twisting up (and storing energy) when it is driving and then release it this energy as torque when extrusion is stopped or reversed. My thought would be that it is very hard to get a good quality print with a remote drive as the stored energy will result in very poor print quality.

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You can have a double braided cable which is internally braided in the opposite direction of the outer shell. This offers the ridgitidy needed to transfer the motion, while maintaining the flexibility.

Much like the flexable screwdriver things if youve ever seen/used one)

https://flex3drive.com/

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nice video, at least he is real about his videos that sometimes boards just blow up, well not randomly blow but we are all human.

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Interesting but I’d still like to understand how much the cable can twist up - I’m sure there are ways to mitigate it, but there will be some twist. For something like a screw driver or or a drill, I don’t see a problem but a few degrees in the cable can conceivably result in some undesired filament movement.

Maybe these things are so torsionally rigid that it isn’t an issue for 3D printing, but before investigating it, I’d like to see some specifications (and a recommendation from somebody I trust).

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I made a prototype machine with flexible drive shafts to operate 2 counter-rotating belts that had to be adjustable and move 2m/s. There were some problems. The cables inside are wound and only work well in one direction. the ones we tested were supposed to be able to work both ways (wrapped twice). it was possible to load up energy in the cable and if there was a jam it could cause a dangerous condition when the jam was released, and we pulled the plug on the idea then. To overcome this we would have had to oversize the flex shafts to the point where stiffness would be too much for the structure that was supposed to hold it all in place and make it movable.

One good way to do this and not have the backlash is to use a splined shaft across the width. this would keep the weight off the traveling components but is way more expensive. this is the route we took on another machine. the splined bushing on the movable part was made from Ampco bronze and pretty expensive, but had a 5-year service life. it could easily be Delrin on something small like a printer.

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