Connecting wheels with gears - 3D printing

[limpet]

I`m trying to design a set of wheels to run from one motor, ie one wheel is powered via gearing, from the other wheel.
It is, as I expected, not as simple as it sounds to get the correct sized teeth etc.
Is there a calculator or something I can use, or even better a ready made 3d file I can mess around with? I`ve had a look through the sketchup ready made components but I can`t find anything really suited to what I want, even with editing.
Thanks

[Shakey]

I used the sketchup plugin called 'involute gear'. Though it took A LOT of attempts to get right.

[limpet]

Thanks, I managed to work something out but I`ll look for it anyway, I couldn`t find anything in the plugups when I looked.
What you have there is very similar to what I`m planning (drive wise), it will have one motor at the front on one side and one at the rear on the other, all the controls etc in the gap in the middle.

[limpet]

It`s not going well! Spent most of yesterday struggling to get it working but I think I will need to redesign it, I havn`t left enough room between the wheels to get a decent axle on the intermediate gears. I might follow your centre drive method too as there is too much loss/friction to get power to the end wheel.
Still on the good side I don`t need it till Saturday

[limpet]

I've now found an involute gears plugin for sketchup, a few others on this site too.

http://www.suplugins.com/registered-user.php