Sprockets and Wheels not Concentric?

[ttldomination]

Hello Everyone,

While attaching the sprockets to the plaction wheels, we realized that the two entities were not attaching in a concentric manner. Meaning that as the wheel spun, the sprocket spun, but it kind of bobbed up and down.

Seeing as how the plaction wheel have those massive through holes, I was wondering if there's a trick that we're missing.

Thanks,
Sunny

[AustinSchuh]

I learned this trick from Adam Heard.

Assuming you are using them in the dead axle mode, put the bearing that you are using to make it dead axle through both the wheel and the sprocket. This will force both of them to be concentric to the shaft, and solve your problem.

[ttldomination]

Thanks for the suggestion Austin, I'll be sure to forward this to the team.

Just thinking out loud here, it would seem that the screws that seem to hold the entire wheel together line up with the AM spacers and sprockets. I'm guessing that would also work...

Thanks for the help,
Sunny

[ajlapp]

The holes on the Plaction wheel are clearance holes. They are not designed to be used as a piloting feature.

The bearing trick mentioned will work. Another option is to design an assembly fixture. We have one made from 1/2" TGP shaft and a turned piece of aluminum. The aluminum has a shoulder which properly pilots into the bore of the sprocket, the 1/2" shaft then pilots into the bearings.....when you tighten up the bolts everything will stay positioned properly.

You can also do a pretty good job just eyeballing the alignment if you spin the wheel with a hand drill, drill press or lathe. At a few hundred RPM's you should be able to see the "wobble".

Loosen the bolts, adjust the sprocket, re-tighten and check. This can get you more than close enough for a kitbot chassis.