Shaft adapter question (motor shaft to wheel)

I have a motor with a 14mm shaft that includes a 5x5x25 key on it. I am attempting to attach it to a standard pitching wheel most likely by means of a trailer rim hub ( Seachoice 53021 1 Inch Trailer Wheel Galvanized Hub Kit) . The size of the rim is 3.75 and it includes 4 bolts. Any help with my shaft to rim connection would be greatly appreciated. I have seen people use the Trantorque bushings but I cannot find one accepting the 5x5x25 key.

This is going to go outside the off-the-shelf parts ecosystem we see in FIRST Robotics Competition applications, but I’m sure answers will come.

To make life simpler, can you clarify your units? It seems like you’re mixing metric and imperial units.

Trantorque bushings don’t need a key. You just crank them down tightly. I’ve used them on keyed shafts before without an issue. Remove the key first.

If the shaft has the key built in, that’s a different problem, and can be addressed with a Dremel, a file, and a power supply for the motor.

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Thanks for the reply!

The units for the shaft are mm and the 5x5x25 key is also in mm. 3.75 is in inches (sorry I should have specified this). On further communication with the company that makes the motor, he said that he could “make the shaft with any shaft size”, so in this case would you have any suggestions for what size I should ask him for?

The CIM has an 8mm diameter shaft with a 2mm keyway. That would get you the best results using standard FRC parts - AndyMark has a hub that’ll fit right on a CIM, but hubs we deal with may not be big enough for you (1.875" diameter bolt circle). You could construct an interface between that hub and your rim, though.

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I was thinking about the CIM shaft size, but another option closer to the current motor’s shaft size of 14mm would be a 1/2" shaft with a 1/8" key. That will also interface fairly easily to the standard ecosystem of FRC parts (lots of options for 20dp gears etc with 1/2" bores that you can either key broach yourself or buy with keyways, and AM sells a 1/2" key 1.875" bolt hub). You could try asking for 1/2" hex, but I suspect you might get laughter in response…

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Andymark sells an 8mm to 1/2" hex adapter


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