4" er should have worked. Don't mean to insult you but you do have the depth set above the concrete right? It will bounce around on you if you do not. You need to get the final bit of material with a chisel or something.
Might need heavier tape and a finer blade though? Router, rotozip or something might work if you have clearance for it. I have a Fein multi-tool that has worked for such things so am surprised your similar functioning tool did not.
I guess you could step down to something smaller than 4" too. Something Dremel class, for example?
Might need heavier tape and a finer blade though? Router, rotozip or something might work if you have clearance for it. I have a Fein multi-tool that has worked for such things so am surprised your similar functioning tool did not.
I guess you could step down to something smaller than 4" too. Something Dremel class, for example?