I have an abundance of hot-roll plate curtesy of local scrappy but facing/thicknessing it in my mill without powerfeed is tedious and either messy with a flycutter or lots of toolmarks with the endmill sizes i have.

I get a much better finish on the lathe on smaller pieces but thinner and larger pieces in the 4-jaw I'd have to remove the gap to clear the jaws.

So I wondered about cutting some shallow slots into the edges of the plate and making up some low profile grips with countersunk heads to hold the plate to the faceplate.

say 150mm x 150mm 8mm plate with a 2mm wide 2mm deep slot in each edge with a 6mm thick holddown clamped through the faceplate so that i could skim as much as 1mm off each face and end up parallel?

The question is would that hold securely enough on cuts heavy enough to get through the millscale without the plate leavng the lathe and brown trousering me? Or is there a better way? Direct bolt-holes through the plate would lead to lots of waste to cut away.