Crazy Horse jet finishing torch

["Simon Brown" <moonsong@zzzzzzzzzzzzzzz>]

Hi Robin,

Lucky you! I'd love to see this work. Have you visited the website?...
http://www.crazyhorse.org/carving/inside/index.shtml
Apparently, the jet torch "... runs on diesel fuel and compressed air" and
is used for finishing the stone surface after drilling and blasting has
removed the spoil.

I have read of these torches used for cutting opening trenches in dimension
stone quarries in Europe, they are ideal for bulk removal of stone as long
as the debris has somewhere to escape to. I have experimented with an oxygen
thermal lance, but it is too violent a method for accurate cutting and just
breaks up the stone. Oxy-Acetylene equipment is readily available, and there
is a wide range of tips for different jobs, with a small risk of overheating
the stone (easily controlled with water spray).

I have read conflicting accounts of the finish produced by thermal
treatment, some sources say the surface is sealed and therefore impervious
to weather, others say that the surface is opened up and the stone weakened
by treatment. I think it depends on the type of stone and the thickness
(being able to absorb some heat without developing microcracks)

Simon