wheels

FIRST Robot Showcase
1

Team 1280 is working on a new drive train (new to us, anyway). We are looking for wheels in the 6 inch diameter range to use with stick-on tread. What have other teams used for wheels, short of turning them out of billet aluminum?

2

You might take a look around here http://www.robotcombat.com/marketplace_wheels.html

3

we have made 6 inch wheels out of inch thick ply (25 mm) then sticking three of them togetehr and covering them in rubber using a mould. This is very heavy for a wheel but you can cut out the middle, or use a thinner layer of rubber…
we did the same this year but we used 8inch wheels … we had too much weight and grip and had to replace two of them with castors … we couldn’t turn as they had tooooooo much grip…

4

Traditionally, Woburn has used sheets of birch plywood (12 mm thick per sheet) and laminated them together into squares. The centre bores are drilled, and rough circles are scribed and cut out. They are then lathed to the appropriate diameter (between 6 and 8", depending on the year) and thickness (usually about 1.5"). Six lightening holes are drilled with a large Forstner bit, and the wheels are painted to resemble metal (just for the hell of it…). Depending on the year, some sort of conveyor belting is often attached for tread, but the pattern varies, depending on what’s needed and what’s available.

5

Sounds interesting. What so you do for a hub?

6

It is the hub.

Think of it as a primitive bushing. Woburn has used a 0.5" bore on the drive wheels for at least the last five years, each time using a wooden wheel with no special hub. It hasn’t failed yet. The shafts are usually embedded in needle bearings or bronze bushings, and are free to rotate independently of the wheels (since the sprockets are themselves bolted to the wheels, with spacers as necessary). Last year, confronted with the need to save weight, instead of ground mild steel shafting, Woburn used 6061-T6 aluminum shaft from Home Depot. It was perfectly acceptable for the 3.5" wide wheel wells.

7

haha i just asked Neel today how Woburn made their wheels