Hi folks
More saga of the lost wax castings with the extra ceramic to dig out.
Needle descaler worked wonderfully. And much less dust.
But zero dust and most work done - big several-kilo pneumatic breaker. Very controllable - real "big pussycat" of a machine. Rounded smooth chisel end - just don't catch the casting full-on. But is soft so burrs over when breaking up metal infiltration into ceramic plug.
Able to flame-harden chisel?
Thinking roaring oxy-acetylene cutting torch preheat flame (enough for cut 25mm plate!), very rapidly heat tip to red hot and quench in oil. Part oil-quench, part self-quench. ie. "flame harden"(?)
Good idea? Bad idea? Temper makes it OK idea? Temper 300C ("straw" colour patina)?
These chisels have been used to break-up red-hot dross in ladles - there is no previous hardness to loose.
Richard Smith