[QUOTE=Flag Captured;453426]

Quote Originally Posted by Flag Captured View Post
I'm not sure how the stuff you use stacks up to Hardox, Glen, but I'm not sure I'd like to try 3.2mm knowing that!
After bashing away at Demon for years with hardly any dents to show for it, the steel must be the hardest known to mankind! Given the weight of the weapon, motor and batteries to drive it, I think you are stuck with 3.2mm Hardox. Its not all bad though, you can use clever design to make the frame stronger.

Quote Originally Posted by Flag Captured View Post
I don't want to make the whole thing so shock absorbent that I end up losing a lot of the power out of the bar
Its actually the other way around. If you make the frame really stiff in the vertical direction, virtually all the energy will go into the opponent. If the bot runs on skid pads at the front, place them right under the weapon support columns and the path of the impact force will look like this:



As long nothing along that path bends, the other bot will be heading into orbit .

Quote Originally Posted by Flag Captured View Post
I'm hoping to stick a bearing in that outer side, so might end up with 10mm between the wheel an the outer edge, might be alright...
That should be fine; if not, you can always increase the floor clearance a little to compensate.

Quote Originally Posted by Flag Captured View Post
Something I will ask though - is there a calculation that can be use to determine say, what thickness of material you'd need to use for a set of bulkheads, or is it more just trying it out and seeing how it gets on?
Top-end CAD programs have a feature called Finite Element Analysis (FEA) that can analyse stresses and predict how much parts will bend or break. You can then tweak the design and rerun the FEA until you are happy (or bored )