NovaPro V4 - Flex Shaft Driven Dual Feed Gear Extruder

by piercet Dec 21, 2018
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This is a very cool design but I wonder, what´s the smaller curvature you can do in the flex and it will still work? I mean does it work if you bend the flex shaft in a 3cm radius?


The more you curve it, the more friction you have on the rotating mass which is going to primarily affect your retraction. You a also need the cable to have enough movement for full travel range. If you had it briefly at 3cm at end of travel it would probably be fine but I wouldn't recommend a bend quite that sharp.

Thanks a lot for your answer, I was thinking about routing the flex shft inside the energy chain in the X axis with all the wires so is not hanging freely on top of the ganthry so thats why the 3cm radius or 6cm diameter curve.

Nema 17 shaft driven replacement? I like my extruder, I just want to move the heavy metal bit (motor) off to the side but have the flexibility to use any extruder. Thoughts?

That would be pretty easy to do with an 8mm hobb drive or a 5mm. I'll see about working a bolt on adapter up.

Cool. I like the concept of reducing weight with an all-in-one solution, but the bolt on solution I think would be super popular. Was going to give it a go myself, but you've already shopped around for parts and made something that looks good.

Its going to be a really easy retrofit I think, The same gear pocket on the side of the nova pro, then a NEMA 17 5-8mm thick plate with a 5mm shaft bearing, and then literally just a piece of 5mm shaft cut to length. Will probably need a right or left handed piece, but this should be an easy build, I'll see what I come up with

Hi, Tim. Nice to see when somebody already did what you were only going to do. Good job! Congratulations! Except flex shaft and dual gears I had one more thing in plan: changeable hotend. Just to have an option to quickly change the nozzle size. Instead of using E3D V6 we can use CR8 (or CR10) heatsink + the group (nozzle+volcano+heatbreak+thermistor+heater). The heatbreak in this group is mounted with one screw only. So you have several those pre-assembled groups with different nozzle sizes and change them using only one screw.
One more thing. When the carriage goes along X axis the shaft rotates even if the motor shaft is not turning. This will lead to small overextrusion on one side of the heatbed and small underextrusion on the other. To prevent this the motor has to be able to turn around Z axis. Motor mount should be on a bearing.
And one more thing. If you can make this whole head changeable - you're famous forever.

I'm not familiar with the cr8 or cr10 hot end mount, I'll take a look and see if I can make that work. There is a quick change picatinny rail mount variant of this in the works as well, I just haven't finished it. Same thing with the dual extruder. The rotation on movement is definitly a concern, so far in testing where I have the motor mounted is close enough to inline with the travel axis that it doesn't seem to move enough to cause a noticible variation in the part with the high gear ratio. I'll see if I can't incorporate a moving mount of some sort. My concern is that allowing the motor to move would actually decrease accuracy on start of shaft movement because the motor might turn instead of the shaft. ( kind of like the old cartoon where the guy holds the airplane propeller still and the airplane body spins instead.) The overall mass difference would probably prevent that but it's something I'll need to account for if I go that route. Thank you for your interest in the project and your feedback!