Stainless steel vent

[hubert_s]

Re: Stainless steel vent

Thank you, John.

When I wrote sheet metal, I meant the stainless steel variety.

[GianniFocaccia]

Re: Stainless steel vent

In that case I don't think you need the SS tubing frame. How thick ya gonna go?

[hubert_s]

Re: Stainless steel vent

I think 16 gauge is probably ok, but I don't really know what minimum thickness is required and have not heard back from FB yet about the thickness on the Artigiano vent. Any recommendation would be appreciated.

[GianniFocaccia]

Re: Stainless steel vent

The Simpson Duravent flues are 24 gauge, so I think you'll be fine. I would bet the FB flues are fine too, although a little on the thinner side. Remember, the oven exhaust mixes with outside air so its a bit cooler when it hits the flue.

[hubert_s]

Re: Stainless steel vent

I bought a sheet of 16 gauge stainless and had a lot of material left over after fabricating the vent. So I decided to build a stainless steel oven entry after all. At this point, the pieces are just tacked together. It fits pretty nicely and I think warpage won't be a big problem. I bent all the edges back and the whole thing became surprisingly stiff after I tacked on the return for the entry.

On the back side of the stainless steel, I plan to put 1" thick insulation board. Does anybody know a good "glue" to attach the insulation board to stainless steel? At the big box stores, they have a product called "Rutland Furnace Cement" made for bonding stainless steel and masonry. Does anybody have any experience with this, or is there another product I could use?

[shuboyje]

Re: Stainless steel vent

I would personally weld some light gauge stainless wires to the back side of the entry and poke them through the insulation then bend them over 90. The thermal transfer will be minimal, and you will have a mechanical connection instead of some form of adhesive which in my experience never work as advertised in Wood fired ovens. I used a stove gasket adhesive on my coal oven doors rated for 2000F. First time I fired it to 1000F every gasket failed. just an example.

[hubert_s]

Re: Stainless steel vent

shuboyje, thanks for that idea. For the most part, the insulation will be constrained between the brick arch and the stainless steel after installation. But that won't be the case for the vent, where I was planning to attach insulation board all around as well. I will use some mechanical way to fasten it based on your suggestion.

[wotavidone]

Re: Stainless steel vent

I used 316, i think. It is about 1.6 mm thick. The various panels are welded together with no backing or framing. Folded edges to stiffen it though. Mine is suspended, doesn't weigh on the oven at all. I'd invested in a auto darkening helmet, and I was surprised how easy it was to weld compared with mild steel.
A welder mate told me it is actually harder to keep a molten pool of stainless steel going. This welding was done with an ancient Lincoln AC stick welder, set on either the 45 or 60 amp tap.

(The story of how I came by that welder makes most blokes laugh. Bloody auctioneer at a clearing sale got me a beauty by accepting my half hearted opening bid. It's a pretty good welder for $40, though.)

The technique is simple. Do what some pros do when forced to weld thin metal with arc. Strike the arc, run for no more than a second, lift the stick for a second, the strike the arc again. Keep going like that, and the steel doesn't burn through and warp.

[hubert_s]

Re: Stainless steel vent

An auto darkening helmet makes things a whole lot easier. I used a MIG welder and welded short sections and then moved to a different spot on the other side. I did get a bit of distortion where I forgot or was not able to clamp things down.

On the vent hood, I just punched a bunch of holes for spot welds in the flanges before bending them down. The collar for the chimney pipe was my biggest problem because I cut the hole too big. I did have a problem there in one spot where I burned away the edge a little, but was able to fill it in.

Aside from the auto darkening helmet, the best invention for the hobby welder has to be the flap disc. It is amazing how quickly ugly weld beads disappear with a 40 grit flap disc on an angle grinder...