Hi everyone,
My team and I need to couple a hex shaft to a 10 turn potentiometer (linked below). Is there any good way to do this? It’s currently hot glued. I’ve seen the Armabot coupler, but it will not arrive in time. Thanks
Drill out a hole in the shaft using a lathe and epoxy it.
Do you have access to a 3d printer? This would be a perfect application for a printed part. Libraries sometimes have them available if schools/sponsors don’t have one.
You could try taking a 1/2" 6-point socket with a 1/4" square drive and epoxying or hot gluing the pot shaft into the drive, for a slightly less permanent solution than epoxying straight into a hole in the hex shaft. Epoxy is stronger than hot glue and will hold permanently. Not sure about concentricity, but it might be worth a try if you’re in a real pinch, since most hardware stores should stock a 1/2" socket. Some hot glue between the socket and the hex shaft might be helpful to keep backlash down.
Yes we do have access to 3D printers. We originally 3D printed a connector but there was slippage. Epoxy would help with that?
Maybe start with a non-permanent adhesive, and if it doesn’t work, move on to a superglue or epoxy. Epoxy can be finicky to work with so be mindful.
You could also try different 3d printed bore diameters to get a good press fit onto the potentiometer shaft, or incorporate a hole to tap a set screw onto the shaft.
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(1) Get some thunderhex from Vex. AM churros might work also. Both already have holes drilled into them.
(2) Pull out a hacksaw. Put the shaft in a vice and cut a vertical slit in the shaft a bit longer than the shaft length on the potentiometer.
(3) Insert the potentiometer
(4) Slide a shaft collar over the split shaft and tighten.
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Sounds like a really good solution but then there’s the problem of connecting the churros to the hex shaft. Thunderhex would work well too but we don’t have any, and can’t wait for the shipping time. We might just use the lathe on regular hex shaft, cut a slit, and then use a hex collar around that like you suggested. Thanks
Yeah, so I was thinking that you would use the churro as the hex shaft. Note, though, that churros bend easily, so you don’t want to use it when you’re going to be putting high loads on the shaft.
Of course, if you have a lathe, then this really isn’t an issue.
Try adding a set screw
(also if you heavily rely on these I would recommend having a drop in replacement ready, we had a wire come off our pot in semi finals but were ready to play in the next match thanks to having a replacement available)
seems like a 3d printed coupler and some hot glue would fix the problem
drill a hole in the end of the shaft, so the pot shaft can fit inside it, loosely. then drill a tiny hole perpendicular to the shaft, through both the hex shaft and the pot shaft. Put a piece of wire through the tiny hole, and twist the ends together.
Wow there are a lot of good solutions here. I just modeled a coupler to 3D print, and if it works, I’ll post the file. If not, we’ll definitely try lathing out the hex shaft and using some epoxy or the string solution. Thanks everyone 
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You can also use a hex hub to couple a solid piece of shaft to a churro or thunderhex, or even to use one of those to line up a (reasonably) centered bore in the solid shaft.
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You can turn down the end of the hex shaft to 1/4" outside diameter, then use a short piece of 1/4" inside diameter rubber fuel hose to connect the two shafts. Those 10-turn pots turn effortlessly and a tight wire tie at each end of the hose will keep the shafts from slipping.
It works much better than you might think it would.
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