Sloppy Denso coupler

[kamocat]

I'm using a denso window motor, direct-drive onto a 2 foot arm. It appears to have enough power (and more than enough speed) for the application. However, the coupler has 7 to 10 degrees of slop in it. (On the two foot arm, that means it wiggles 3-4 inches)

I'd like to drop that down to below 2 degrees of slop, but I want to keep this coupler as a coupler, not a permanent joint. What's a good way to do this?

I tried hot glue. Unfortunately, I wasn't careful enough for it to create a tight fit, and it ended up just sticking it together without decreasing the slop. (I'm sure I can wrench it out, but I haven't bothered yet)

Another idea I had was to use newspaper - this is a cheesy method I use to press bearings into sheet metal when the hole isn't undersized. However, this isn't ideal because it would need to be redone every time the coupler is removed.

Would tape be a good option? Would most tapes squish out of the way too much and develop slop over time?

[MrForbes]

maybe put a few set screws in it?

[MrForbes]

or saw a slot or two in it and put a hose clamp around it?

[Tom Ore]

We had the same problem with our minibot deploy arm. We replaced the denso motor a couple of times during the season to keep it tight. We did take one apart to look at the coupler, but I don't have a good fix to recommend. (For a competition robot it probably isn't legal to modify the coupler.)

EDIT: Our problem was the rubber coupler inside the motor. It's in between the gear and the output shaft. If you grab the output shaft and turn it back and forth, you can feel the extra backlash. I assume the rubber is taking a compression set.

[Chris is me]

Make a new coupler. That thing is really not good for arms. Our arm had 20+ degrees of "dubstep wobble" because of that coupler.

[Hawiian Cadder]

i might recommend some type of thicker glue, like epoxy. see if you can find something that dries to a hard, non-flexible substance.

[Tom Line]

If you are talking about the external plastic coupler, you can try this:

Get a nice 2 part epoxy. JB Weld will work in a pinch and can be bought in smaller amounts. If you were a sailor I'd recommend West or something else with a colloidal silica mixed in for strength.

Put a piece of saran wrap over the drive shaft that comes out of the motor. Mix the epoxy and put it into the plastic coupler. Put a pretty decent amount in. Press it onto the saran wrap. The saran wrap is acting as a release agent.

Once it's dry, slide it off, peel out the saran wrap, and use a dremel to remove the excess epoxy.