Connecting a wheel to an axle?

I'm putting together an arduino controller for a robot I'm making and I need to connect wooden wheels to a 1/2 inch bar I'm using as a drive shaft however I can't find anything to make the connection between the two.

I'm after something like this http://www.microrobo.com/12mm-universal-aluminum-mounting-hubs-18010.html

I would be drilling a hole through the drive shaft and attaching the wheel that way but finding something like the above in the uk is proving a struggle and I have a bad feeling 12mm might be ever so slightly too small for a 1/2inch bar.

Does anyone know of a uk supplier of the above or any other technique for connecting wheels to drive shafts for DIY robots?

Many thanks in advance.

Bar? Do you mean rod? Bar is square or rectangular.

1/2 inch is 12.7mm

Cut a slot in the face of the wheel and use a roll-pin through the shaft?

Ah fair enough rod yes; and thanks for the tip on the roll-pin I'd never heard of them before.

Check out SimplyBearings.co.uk.

Loctite or compress it on with a .001 shim

I'm putting together an arduino controller for a robot I'm making and I need to connect wooden wheels to a 1/2 inch bar I'm using as a drive shaft however I can't find anything to make the connection between the two.

What is the size and design of the wooden wheel? Up to a certain size, hot glue might be an option.