Well, I've decided to have a go at this...

I think you'll be fine having the blade 4 inches off the ground. I've just gone through my pictures from the most recent featherweight championships and while there are a few low robots out there, there are more that are 4 inches or higher, so you should make contact with a lot of them. And even if they are lower than 4 inches, you'll have the skirts to coax your opponents up into the blade :twisted:

If you decide to go for an undercutter, I'd suggest trimming the blade to about 600mm long max (depending on design) as you'd probably be looking at a very large and structurally weak robot otherwise.

Sounds like, with the CNC and all, that it should come together pretty quickly. Think you would have it ready for the tag team championships in September if you throw a drag-racer together too? :)

Pretty sure I will do, once exams are all over and I finalise designs it should come together worryingly quickly.

Nope, not going to be an undercutter :twisted: as I was saying before, that's what the skirts are for...

As for a drag racer, while it would be tempting to get a trashed kart from the kart track my mate works at, hammer it back into shape, and weld a bunch of chainsaws on to power the back axle... I'll probably (if I go) just end up getting a battered old belt sander or circular saw or something, and cable tying some poles on to make it go in a straight line :P