The problem with scalpels is the blades are too flexible for the force the mounting allows. I have seen a scalpel buried to the hilt in vulcanized rubber, and cut perfect freehand V grooves for white metal runners. But try to pull them along a straight edge, and you can't feel the resistance of the edge, so the top wanders around, which causes the tip of the blade to wander around. The only thing they are really good for is freehand trimming of molding flash and the like. And decals... really good for fine trimming of decals.

Picture yourself reduced to HO scale, and the size blade needed to dice off 2" dimensional lumber... that's the single edge razor blade. The scalpel is a pocket knife by comparison.

Dennis Storzek