Let's Make Robots!

Attempt At Making Robot Wheels

Hey guys,

It has been a while since my last post.  The Vulcan Five is not looking too good beacuse of the PCB fiasco.  I'm trying to salvage that situation, but its going slowly.  So unfortunately for this coming up competition it will not be entered.

However recently I have been experimenting with making my own robot wheels for maximum grippage on my sumos.  Here are some puctures of the results.

So some details.  The hub for this test wheel is 1" diameter acrylic rod in which I machined a hole large enough to accept the maxon motor you see in the last picture.  I found some cheap containers at the local Dollarama.  I drilled a hole in that and used a screw to line everything up.

I then mixed up some of the silicone rubber.  Mold Max 30 from Smooth-On (cause thats they only thing the hobby place had).  It has a shore 30 rating the same as the tires on the Vulcan Five.  I then used a syringe to pipe the rubber into the mold.  Then comes the waiting.  About 16 - 18 hours for the rubber to cure.

The next day the rubber was hard and ready for demolding.  However I wasn't able to remove it from the mold that easily.  Seeing as this was a test run I just smashed the mould apart to get at the wheel.  It was pretty grippy but could be peeled back from the hub, so I would have to put some channels in the hub to prevent potential slippage.  Running it across a surface I noticed that it picked up a lot of dirt and debris.  But a little warm water and soap should clean that up.

I would call this a success, but I would need to rethink how to do the mold so that I can remove the wheels without destroying it.  Once I get all the kinks worked out I'll try to post a walkthrough.

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Check out my mini hightower robot. I developed a way of making wheels using 5 CDs per side. I used a 5/16 nut and ground down the cornerd to have a snug fit. The ID of the nut holds a servo horn in place and used a small drill and servo horn as a drill guide. Hint, i used a small allen wrench to dowel pin the CDs after the first hole to prevent from moving. Worked great and plan to post a detailed process when I get time.

 

A really easy way to make wheels is to use a hole saw:

and use the circular cut out as a wheel.

If this is just about getting grip, there can be only one material: The kind that is used for these plastic / rubber / slimy hands and stuff, like this:

Indeed.  I believe they would be made from a similar silicone rubber, probably at a lower shore rating like these lint rollers are.  If I could find these at the dollar store it would be instant wheels.

 

Find old printers, fotocopiers fax machines... older HP, and epson models have 52mm outer diameter wheels with a nice rubber around it for traction.

 

like this:

 

 

 

 

 

 

 

 

 

 

 

 

 

ain't they awsome?

The problem with using a CD or the printer roller is they are too big for a sumo.  Well thats just my opinion.  For a low profile sumo you need small wheels.

I made my own wheels by using mold rubber for the tire and 3d printed plastic for the hub. You should be able to use anything porous for the wheel hub so that the rubber can stick to it. 

Molded Rubber Wheels

You can download the .STL file from thingiverse http://www.thingiverse.com/thing:1505 to print it on a 3D printer if you have one.

I used PMC 121/30 Dry from http://www.smooth-on.com/ to make these wheels.