Respooler woes

Space Teams 3D Printers
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As you’ve probably noticed, there’s been a semi-functional respooler in the 3DP area for a while. I keep getting it almost working and then break a part and need to reprint it. There are currently two sticking points: the axle that the handle runs on and the friction of the mechanism as a whole.

I’ve tried printing the axle in PLA, PETG, and ASA. It’s either too brittle and snaps (PLA, ASA) or too soft (PETG) and twists. You can see it twisting in the picture below (red arrow). I’m printing the “Stronger 45mm Axis with 5 walls and 100% infill” version of the axle from here: Bambu Lab P1 / X1 / X1C / X1CC Filament Spool Switcher & Winder if you use AMS by Miklos Kiszely | Download free STL model | Printables.com

It seems like the cause of this is that it’s taking too much torque to turn, which seems to me to be because of friction or binding of the axle that the filling spool rides on (blue arrow). When it’s working well, it turns pretty effortlessly, but every so often it becomes harder to turn, and I think that this is when the axle damage is occurring. I’m not sure why it becomes harder to turn, but if I remove the receiving spool, it turns effortlessly again. Returning the receiving spool usually realigns something and makes it easy to turn again.

It seems like my options are to find a way to make a stronger axle (resin print? machine out of metal?) and power through the sticky parts or figure out what’s causing the friction and try to fix it.

Any ideas?

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1 Like
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Is the red arrow a shaft? I say make it out of aluminum.

I think the blue arrow shaft could be made from a hex shaft. Add a bearing where the arrow is pointing and print the herringbone to slide onto the hex shaft. I’m thinking 3/8” hex

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Yeah. The annoying thing about it is that it’s keyed. It would be easy enough to turn a rod to diameter and mill hex flats on one end, but I think I’d have to mill a pocket and drop a key in it to lock it to the gear. I probably have a small enough endmill for that, though.

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What is the size of the key?

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So I think I’d use a 1mm end mill to cut a 3mm wide, 11mm long, 4mm deep slot and drop a 3x10x5 key in it?

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And the orientation of the key relative to the flats of the hex doesn’t matter, so I’d probably end mill the flats (cutting in the XY plane) rather than side mill the flats (cutting in the XZ plane), and just do the slot while cutting a flat. Not sure if Asmbly has a hex collet block.

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I had purchased some inexpensive hex collet blocks in the past. The somehow weren’t concentric. I returned it. Hopefully Asmbly has some good ones