First build

[landuse]

You've got it the wrong way around, Paul: It's always about the diameter of the sprockets/pulleys/whatever. The fact that sprockets happen to have teeth just makes it easier to figure out the ratios.

Thanks Fabroman.

I do understand about the diameters, that is why I said that with pulleys you use diameter instead of teeth. What I was trying to say, just to make it easier for the op, was that the relationship between diameters within each individual pitch sprocket is always going to be the same. You won't use a #35 with a #40. So to make it easier, and less complicated to understand, when calculating gear ratios using sprockets, using just the tooth count is much easier.

 

[ballistic]

Okay, this aint gonna be as easy as I orignally thought. I cut and started welding the frame together, it looks more like a rocket car frame and my nephew says my welding looks like bird ****. Using 2.5mm x 25mmm square tubing and so far it seems very heavy. Still haven't had a chance to upload any pics, as soon as I can take some I will upload them. But so far, the frame is assembled, front and rear axles are welded in place, just need to fit motor, brake and petrol pedals and get my gearing sorted out.

 

[OzFab]

Using 2.5mm x 25mmm square tubing and so far it seems very heavy.

You get that when using thick wall material. Rule of thumb is to increase size, not wall thickness:

"It's better to use larger thin wall material than smaller thickwall material"

For a small kart, 25mm (or 1") SHS with 1.6mm wall will suffice

 

[Doc Sprocket]

2.5mm? Yeah, that's quite thick indeed. Works out to about 3/32. I did that, and regretted it. Then again, the steel was free, and it ain't gonna fold up no matter what cliff it's driven off!

 

[OzFab]

Absolute worst case: Make the frame airtight & fill it with helium