Hello everyone, DJ again.

Thanks for the help. Hopefully some of the advice on here would help.

As for the size of the axle, I'm thinking about (quite possibly overkill here...) going for 7/8" axle thickness. But if this proves to be a little overkill, we may tone it down to 1/2" or 3/4".
The sprockets will probably stay at a 3/8" chain pitch, but we may go for duplex sprockets to see if that'd help for reliability purposes. My mind says it might do, but my gut says it might not...

Speaking of which, I have little to zero idea on how to mount said sprockets and wheels to the axles, especially if I want the robot to be primarily a push-bot/spinner killer. Which means power and armour first, weapon as an afterthought, but I digress. As said before, I have no access to CNC or CAD, or any drilling/proper cutting platforms so to speak, so any way apart from the key and keyway technique would be fantastic. I looked up something called "Trantorque" via the RioBotz combot tutorial pdf, but I'm not exactly sure how this'd work seeming as I haven't seen any tutorials that show people mounting a wheel or a sprocket to said axle. I'm also not sure how much they'd cost either...

I also have a couple more questions to ask but it'd probably be better if I start working on a prototype, and ask then. I've got wood and MDF in the shed to start off with (and a hot glue gun and nails), especially with the chassis, but the MDF will most likely be used to get a general shape for the drivetrain protection/makeshift gearbox/gearing... I'm not exactly sure what to call it to be honest. Once I get that down, with all the markings, I'll either take pictures and post them up on a blog, say... tumblr, so that I don't swamp this place with unnecessary twaddle, or I'll attempt to get my camera to film what I've done that day, almost like a diary, so to speak.

As for going to a live show, I went to one a few years back, and it was awesome. I believe it was a bunch of either lightweights or featherweights, and one bot stood out from the crowd, as it looked like an I shape with a spinning bar underneath it. I believe it was from the creator of Scorpion but I genuinely can't remember, so I might as well be talking out of my backside. But as I said, it was a few years back.

Once again, any input, feedback, etc. would be extremely appreciated. Fingers crossed I can get the pictures/video out sooner rather than later.