Engineers help please

[nick69]

Right, we've got 2 Mountain boards and want to retro fit go kart wheels on them to enable us to use them on soft sand.
Heres the problem, the boards trucks have either 10mm or 12mm axles, the go kart wheels use 3/8" internal bearings.
Ideally id like to get some:

10 or 12mm internal x 35mm (3/8") external bearings. Now these dont seem to exist.

Anyone got any ideas?

Spanks
Nick

[Andy]

If i think I've read the question right, then possibly the easiest, albeit time consuming way to get around it, would be to make up some bushes for the axles. You'd have to make them an interference fit to stop them spinning though, and ideally something like phosphor bronze.

Other than that, just make sure you search all the bearing manufacturers.

[philoldsmobile]

steel would work well, ideally EN1A or EN16T (not EN3B as its going to be too soft)  You'll need a turner capable of holding close tolerances, as you want the internal diameter of the sleeve to be about 0.01 - 0.05mm smaller than the truck spindle diameter, then cool the truck, and warm the sleeve. even at a moderate temperature difference the sleeve should slip onto the truck easily, then cool to an interference fit.

you should need nothing more than a domestic freezer, and a heat gun to achieve 5 hundredths difference on an EN1 sleeve of that sort of diameter.

the outside of the sleeve wants to be turned to a diameter about 0.1 - 0.2mm smaller than the ID of the bearing, then the sleeve held in a collet, and the centre bored as opposed to drilled or reamed.  you will need to drill a pilot hole about 2mm smaller than the finished I.D. of the sleeve, then finish the rest off with a boring bar.