This is for stove register plate.
1.5mm mild steel sheet to 3mm mild steel angleCan't get to other side to fit nut.
Self Tappers do it? or too thick? I may just pop rivet it on as I'm unlikely to need to dismantle it and not the end of the world if I do have to, almost as quick if not quicker to drill the heads off.
Also need to fix the sheet to concrete don't want to use sleeve anchors - need a nice finish ie pan head. Concrete is a bit crumbly. Can't use plastic plugs - must be heat proof or can I? How hot will the perimeter get?