Once all is said and done, here’s the end result.
At the high end I’m seeing a little more yellow in the flame than I’m comfortable with but that is coincident with seeing the end starting to smoke a bit… I think there are still some fumes being driven off from the paint job that are burning in the high flame so I’m not going to be concerned about it for the time being. Note the beautiful inner cone… the picture doesn’t really do it justice. This phone-camera doesn’t capture the tendril-ly variations in color. Maybe I’ll have to try the good camera instead.
When this thing get cranking it practically whistles with the air being drawn into the tube. Very impressive.
So now I can get on to the furnace proper! A bit more welding and cleanup on the lid, then I can cast the refractory into it. I’ve got all the forms made.
Update: Now that I modified the flame holder with tapered exit threads to reduce back pressure I’ve realized that my “Low pressure” picture above is acutally “Medium pressure.” The further modified flame holder allows virtually non-existant gas flow to generate a soft blue flame with little pressure, no burn-back, and no huffing as I was previously dealing with. Definitely worth doing.