Wheels with gears!

From the Rules thread:

What a great idea!!

I have tried this with metal inserts, it really doesnt work reliably
i only managed to pull out the normal plastic inserts on one out of 4 wheels i tried, the other 3 i tried (and failed) to chisel them out
then i hammered in the metal insert, issue was that it was crooked, i couldnt put an insert on each side, the axle never fit and with only one metal insert it was extremely wobbly

i would definitely prefer using the newer 3.25" omni wheels instead
http://www.vexrobotics.com/media/catalog/product/cache/11/image/5e06319eda06f020e43594a9c230972d/2/7/276-3526-single_1_1.jpg

I was actually thinking of just a repair, but a wheel with an integral gear would be interesting.

I was planning to drill and ream the hub undersize, then chamfer one edge of the gear teeth on the lathe so it can be heat-staked together on a press for straightness, with the hot metal gear melting hub material for a exact fit.

People have been doing this with 4" omni wheels for years, it works fine every time in my experience, just the plastic inserts take a bit of persuading to get out and the metal ones take even more persuading (with a hammer) to get back in again.

Solution we found was get a big wood screw thats slightly larger than the square hole in the middle of the plastic insert and screw it into the insert. That gives you something more solid to pull on with some pliers and it should just pop out. Needless to say this will break the plastic insert but they are pretty useless anyway.

Thank you for the suggestion. ! Some of ours have fallen out naturally, but we were looking to remove the rest and will try this tomorrow.

Tried it last night, and worked fine. I drilled the hub out to 7/16" (15/32" would probably have been better), then chamfered one end of the 12-tooth gear at 45° to the depth of the gear teeth, heated the gear to around 350°, and used an arbor press to insert it straight.

Sounds interesting. Do you have a picture ?

attached…
WP_20151001_002[1].jpg

You aren’t planning on using this for competition are you? Because from what you are saying is that you fused the two pieces together which would be illegal in a competition. Otherwise this seems like it may be useful for non competition robots especially for repair of Omni-Wheels that have had their plastic inserts worn down.

I ran this question past Karthik to see what the Official Q&A would say:

“Yes, this would be legal, however you need to make sure that the heating of the gear does not result in any welding or similar illegal forms of attachment.”

So, as a Welding Engineer, I know full well that metal and plastic don’t weld together. On the other hand, I don’t want to risk a team being DQ’d because an official thinks that this would be the equivalent of adhesive. So, we probably won’t use these wheels in competition but instead save them for the demonstration robots we use at public exhibitions and the county fair.

haha, that creeped me out so much when I saw it, Actually looks reasonably reasonable thou :stuck_out_tongue:

I’d print the Q&A question and if it becomes an issue then show them that it’s been declared legal. I’d pass it for inspection, but the Q@A would cover you.

Nice job!!