Stonemasons chisels

Question

I'll be working with square-cut Pennsylvania bluestone cleft flagstone nominal 1" thickness. Before I actually do anything, I'm trying to come up to speed on splitting flagstone with a tracer chisel. I've read that it's possible to ruin a carbide tracer chisel by misusing it, though the nature of the misuse was not described. I have no idea what that misuse might entail. Striking the chisel with too much force? Holding it at the wrong angle? What things might a newb do with a carbide tracer chisel that shouldn't be done with it?

P.S. I might not even need carbide. Will a plain steel tracer chisel be sufficient for PA bluestone flagstones?

Answer 1

I was able to find some maintenance and use tips for carbide stone working chisels.

Using a dull edge can break the weld, so do not delay in sharpening the carbide if you notice performance is declining; keep the edge sharp and at the same shape it was when new, maintaining the bevel on the edge. Use an 80 grit or higher green silicon carbide bench grinder wheel or electroplated diamond pads, taking care not to remove any of the steel that supports the carbide. Do not quench the carbide cutting end with water or oil when sharpening, let it air cool.

Grind the hammer-struck end of the chisel using an aluminum oxide wheel before it becomes splayed as splaying can lead to cracks in the steel which is a safety hazard; when grinding the hammer-struck end don't let the steel get too hot as that will soften the steel; keep an eye out for discoloration in the steel and cool the hammer-struck end in water often during the grinding process.

Here are errors a novice might commit that constitute "misuse" of the tool:

When using the chisel always maintain full contact of the edge with the surface of the stone; do not strike with the chisel corner only or allow part of the carbide edge to sit on a high spot with the rest of the edge unsupported. Never insert the chisel in a crack in the stone and never use it as a wedge or lever.

EDIT: A corollary to the above rule about maintaining full contact of the chisel edge with the stone: when dealing with a rough surface with high spots, choose a narrower chisel that fits between the high spots.

Even though carbide is very hard don't assume it is indestructible; the carbide is brittle and can crack when struck at an oblique angle.