Question about crack in wood stove

Beeman · #21 03/13/10, 09:39 AM

You could probably seal it with stove cement which is what they should have sealed the pieces together with when assembled.

You said it's a Franklin stove and in my mind I see an inexpensive cast iron stove. Then later you ask about a stove for close clearances which I would guess a Franklin isn't.

**Cabin Fever** · #22 03/13/10, 10:11 AM

While I agree that every home should have a CO monitor, there is really no reason why you need one more now just because you Frankin Fireplace has a crack in it. A Franklin Fireplace has "cracks"....or should I say "leaks"....all over the place. It is not an airtight stove and the doors do not seal. Consequently, CO has plenty of places to escape a Franklin Fireplace even without a crack...even when brand new. Since a Franklin Fireplace is not air-limited, I doubt if one would even produce significant amounts of CO.

With that said, it's still a good idea that every home have a CO monitor.

Andy Nonymous · #23 03/13/10, 10:20 AM

While I'm sure a new stove would have a lot of advantages, hardly anyone I know could afford even 3 Franklins for a new one. We do what we can with what we have for as long as possible and necessary.

I have a wood stove I picked up cheap in 1978, used once (improperly) and with a crack in the bottom, running from the front edge in about an inch and horizontally about 3". I took the stove apart, drilled the inside end of the crack, warmed the area very well with an Oxy-acetylene torch with a rose-bud tip, then welded it with a high-nickel rod. Re-heated the area with the torch to help release welding stresses, and let it air cool. I ground down the face to match, reassembled the stove, put on stove black, and it held for 12 years of use, then the crack started becoming visible on the edge again, but hasn't gone further than about an inch (which is outside the stove anyway) in all the years since. It's heating the house even as I type this.

I would NOT use an epoxy (such as JB Weld) as the heat of a stove will destroy it and very likely give off some really noxious fumes.

"Stove cement" is a misnomer, as it doesn't really give structural integrity to broken metal. It is intended to fill gaps between stove panels that are otherwise held in place by bolts. A break in a panel needs to be mended with metal, whether that be braze (which I personally haven't had much luck with) or weld.

I disagree with FBB, as it is carbon steel that has 'temper' that is affected by the way it is heated and cooled. A chunk of ordinary cold rolled steel, heated to a "red" heat and quenched in oil will develop a "temper" of about a shovel - you can cut it with a file, but it will be 'hard'. Heat it to orange and air cool it, and it will be 'soft' again. Steel at an orange heat will readily bend or sag - cast iron does not. It has to do with molecular structure and crystalline stability.

Cast iron, unless severely overheated and carbonized, does not develop 'temper' as we think of with steel, which is an alloy of iron, carbon, and often other ingredients these days, such as molybdenum, tungsten, chrome, nickel, etc. depending on it's intended use. It's a fascinating and complex science.

As was mentioned above, very thin castings (less than 1/8th inch) may not be worth attempting to fix as a weld may be stronger than the surrounding metal, and the stresses from the weld may cause more cracks near by. Being at the top of the stove, I'd drill the working end of the crack (with a 1/8" bit) and use a daub of stove cement to fill the hole, at least until heating season was done.

Still, for the investment of a few bucks in one nomacast rod (3/32", not 1/8") and a little gas for a torch, you could possibly fix it well for another few (or more) years of use.