That has to be one of the neatest things I've ever seen! Even if you just bandsaw it and groove it with a cutoff wheel, it's still a nice trick.
TRX, I was happy with the way it worked in steel even though the slots are very shallow - i.e. the steel I'm using is about 3.5mm (a little bit over 1/8") and those slots were cut 0.5mm deep (near enough to 0.020" ). I'd be reluctant to cut much deeper than that for fear of making a potential failure point. For that reason, I'd also be wary of trying to cut them by hand with a cutoff wheel. It was easy enough by CNC though
While I'm here, some progress updates. Since I'm on leave now and supposedly working on the car, some friends have been coming around to assist. This is great because it breaks me out of my usual "Paralysis by Analysis" where I spend hours deliberating over things.
So, in result, rear suspension brackets now aligned and fully welded. Toe links still to come.
Plus, some front suspension stuck on too. Don't look too closely at the welding on those brackets. Need grinding out and redoing with the chassis at a more workable angle
Following day and a different friend to help - we cut, folded, and fitted two of the three fixed firewall panels. Not welded yet. Made from 1mm steel, with a 10mm lip folded round the edge to make welding easier. Would be fair to say the second one was easier and a better result than the first.
Also played another round of "Stop Dominic over-analysing solutions to non-existent problems" which means that something I'd been fussing about possible solutions to for 12+ months was solved today by simply not doing it! Was quite liberating once I got used to the idea
Tomorrow (Monday) I'm ordering the roll bar and braces, which will be fully welded into the chassis. Hopefully they'll be made before the Easter weekend. More updates soon....