Furnaces, Ovens & the many wonderful flavors of ‘Large Hot Boxes To Help Make Glass Do What You Want’
At this point, I’ve built somewhere north of a hundred of these damn things. Primary melting furnaces, reheating furnaces, casting kilns, annealing ovens, garages, pipewarmers, and other oddball equipment that defies neat taxonomy. As a general rule, they all consist of some type of refractory material on the inner face to stand up to the working heat, insulating material to hold that heat in, a metal frame to hold it all together, and either electrical heating elements or a fuel-combusting burner to provide the heat input.
The majority of that building happened down at Wet Dog Glass in North Carolina, where I spent a couple of years working and learning how to build glassblowing equipment from one of the best furnace makers in the studio glass world (thanks Eddie!). Since then, I’ve kept building, repairing, and modifying equipment for myself and for other local glassblowers. My record-keeping about it has been pretty atrocious, but what photos I do have are below.
Blowpipes & Punties
I’ve only made myself one set of blowpipes and punties, just for the challenge of seeing whether I could do it or not. I’m all for making your own tools, but pipes specifically are just one of those things that are WAY easier to make if you can tool up to do it properly, instead of working out of a general welding/machining shop. Still, these all came out straight and aligned, served me throughout running my first small glass studio, and I never had any of the welds fail on me. Overall, this project worked out pretty well!
For these particular pipes, I used 4130 chromoly steel for the main bodies, 316 stainless for the mouthpieces, and 309 stainless for the heads. First I machined all the heads and mouthpieces out of solid stainless round bar, and cut the main shafts to length from chromoly tubing. I gave all the solid heads & mouthpieces a small stepdown/shoulder to get a nice press fit into the chromoly tube, to help keep things squared up & concentric. Then I TIG welded everything together with 309L filler rod (best one to use when you’re joining steel and stainless). If you’re interested in the technical details of glassblowing tools, Fred Metz has a great little one-page guide to blowpipe materials & design here.
Blowpipe & punty ends, freshly machined and ready to be welded to the main bodies
It doesn't look like much, but drilling such narrow holes all the way through the parts in this particular grade of stainless steel was quite a challenge!
The welding setup was...definitely a bit rough around the edges. I just used two vices aligned on the welding table (the professionals do this bit in a lathe, so they can keep things aligned while they weld).
Little detail shot of a blowpipe and two punties just after being welded