I gotta do it right sooner or later

[TimB]

I made a door for my schrader wood stove, out of 3/8" red iron from an I beam. The second time, I did a fairly good job welding the angle iron around the edges without warping it, and it worked great for a couple years, but I just noticed tonight that it's warped enough now that it dosen't seal very well any more, and I don't know that I have the time or money to do it again, nor the wood supply to keep the house warm when the sub zero temperatures hit, if I don't get a door on it that seals. Why is 3/8" red iron warping when the 1/4" sheets the stove is made out of don't? By heating the door on the convexed side, over the warpage areas, can I straighten the door? How does this work? It evidently does because the concaved side of the door is toward the fire side, but how does heating metal, which tends to expand it, shrink it more than its original length?

[Glenn Lyford]

I think its a matter of the heat from the fire is hottest at the center of the door, and all around the edges is a little cooler. Since the cooler metal is not expanding as much as the hot center, that center still needs some place to push out, so eventually it bends to give it somewhere to go. The sides of the stove don't bend because they're not held on by a hinge only on one side, they're welded down to their neighbor all the way around. If you run the stove enough, you may eventually notice that the middle of the panels will start to show a bow or sag in spots, especially if it gets up to a dull red there when you're running it.

A bunch of the stoves I've seen have cast iron doors, which I suspect don't bend and warp as much as the red iron.

I've seen some stove doors that are actually double, both to act as a baffle to direct the air from the air controls down low to the fire, and so that the inner layer acts as a heat shield so the outer layer doesn't see as much heat.

Do you think you can straighten out your existing door again, maybe in a press? How about adding a sheet of heavy stainless (16 ga or so, maybe) to the inside surface with maybe a 1/2" to 1" gap using bolts or some similar kind of stand off. If that sheet then decides to bend, or even bend enough to bend the mounting bolts/posts then it still shouldn't be noticable on the outside or affect the seal. You'll lose a little length in your firebox (and I know that can be an issue if all your wood is cut to just fit what it is now). When it gets too mangled (more than likely from trying to slam the door on a slightly too long piece of wood) just replace it and keep going. Stainless bolts would have a better chance of coming apart again later for these repairs (it works on mufflers up here in the land of winter salt, anyway).

[Nakedanvil - Grant Sarver]

Yeah, I'd go for the "heat shield" idea. Don't need to make it quite as big as the door either.

[pkrankow]

A lot of wood stove doors use a ceramic glass or metal plate that can expand at a different rate from the rest of the door. This is held in with some door gasket rope and a metal frame.

Phil

[ArtWerkz]

Perhaps weld a couple of pieces of small angle at the top of the door and the bottom of the door, aka a strong back. Perhaps that will help.

[mike-hr]

We have a big Schrader, I think I could fit the microwave oven in there if I wanted, It has cast iron doors. The reason the inside of the box doesn't warp, is, it's lined with fire brick. I think what ever mild steel door arrangement you fab up will warp eventually, unless you make channels and put those 1 inch thick firebrick 8 inches up, like the rest of the box. I wonder if you could order new cast iron doors from schrader? Cast iron is warp resistant, that's why automotive exhaust manifolds are made from cast.

[TimB]

Schrader is out of business, so I can't get new doors unfortunately, and I undertook this process because the original cast iron doors were on it, and they were warped bad enough that over sized rope didn't work to seal them either. I like the heat shield idea though. Mike, sounds like we got the same size stove. The only one I ever seen that might have been bigger (Schrader) was an octagon or hexagon shape. (I welded a water loop in mine in the 8" space between the top of the door and the top of the stove, and turned it into a boiler, that's why I don't want to replace it.) It looks pretty cool with that 14" x 26" sheet of red iron on it too. Newbie, I had that idea too, I rimmed the sheet with inch and a half angle iron, 1/4" thick thinking that would help keep it from warping, but it did anyways.

Would simply pressing it back flat work, or would it just cause stress that would wind up popping again, like the old cookie sheets used to do?

[pkrankow]

I suspect that just pressing it flat without relieving the stress would let it pop back later.

It may be better to build a frame for the door and hinges and then mount a portion of this door in the frame with gasket rope and bolts. You may want a second frame to sandwich the plate with too. The heat shield would be helpful too. Welding the frame is good, but the panel cannot be welded in. Make sure to leave a good amount of space around the plate for expansion.

Just my thoughts.

Phil

[BIGGUNDOCTOR]

To take out the warp try shrinking the opposite side. Take a torch and heat the center area of the convex side of the warp, when you get it hot, still black to dull red, slap a wet rag on the heated side. You should see the panel bend back some. Keep repeating until you get it straight. I have used this method to straighten a conveyor section that got dropped off of a trailer on loading. Only cool the one side, not both. This is the same method used to straighten body panels on cars, and to put a curve into 6" thick plates.

[Ted T]

Very well said BIGGUNDOCTOR, because it works!!! :cool:
Ted Throckmorton

[CurlyGeorge]

We used that method to pull SS rings together and get them to match up for welding. Heat it, then only add watter to one side. you can actually see it move. :)