Is there any good and robust way to connect Bosch seat motor to shaft?

Hi, Good afternoon!

We are working on the hatch panel manipulator of the 2019 Robonauts Everybot.

The Bosch seat motor has an output bore that is an odd size that is hard to interface with, based on the document of “The 2019 Robonauts Everybot”, we used a ¼"-20 bolt clamping around the thru hole bore of the seat motor. But it does not work, it’s too loose.

Is there any good and robust way to connect Bosch seat motor to shaft to transfer torque from the motor to the mechanism?


The Robonauts use a locknut to increase the tightness and hold it.

Failing that, you have options and more options.

Thank you!

My team used 6mm steel key stock from Mcmaster, actually, and it works great!

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hopefully you’ve already seen the page Andymark has recommending ways to attach. (see Billfred post)

But yeah, the 118 recommendation is to ‘clamp’ it with locknuts. Sounds reasonable…also could act like a clutch and spin just a little if it gets overpowered or forced.

What we did was drill out the threads on 2 1/4-20 nuts and clamp those like washers. They are small enough that they only touch the actual white part of the motor, not the rest of the black ring on the outside. One nut on each side along with a few washers gets the space right, and then clamp tight to that assembly with a nylock nut. So, Bolt head (1/4-20), arm, washer (x however many you need), drilled out nut, motor, other drilled out nut, however many washers it takes to be reasonably tight, other arm, nylock nut. That clamped plenty tight for us.