welding with out warping?

[silvercheck]

I'm building a turbine like a fransis water turbine, or centrifugal fan, or tesla turbine but with fins. I wanted to use 20 gauge Stainless steal but the shop said they can't weld that with out warping it. I want to weld some 20G fins onto a 20G disc at 90 degrees. I see that many pulse jets are welded 20G to 20G, how does it not warp?

[metiz]

It usually does, at least with me. the good thing about pulse-jets though is that they're basically just hollow cylinders so nothing a hammer and a shapped piece of wood/ steel can't fix. You could always try the slow way of welding where you constantly weld a bead, stop, and then weld another bead to the previous. It won't look to pretty but you'll get the penetraion and if done correctly, without leaks. You could also try to lay your metal on some aluminium or copper. It will absorb a lot of the heat and help reduce warping.

[vturbine]

However, do realize that your blades will be faced with uneven heating in operation, as well. Not saying it will be a problem without knowing what the design is, but certainly with the Tesla disk turbine, uneven operational heating can be and has been a problem with disk warpage.

Many small fans, the original Teslas, and many large turbines use mechanical means of securing blades, whether by rivets, or keyed channels. Glad I used rivets in mine, as I had to replace the blades early on.