Cast iron repair

[crazybill]

I am restoring an old cast iron stove. One of the tabs that hold the two sections together is missing. It is a U shaped tab that holds a screw.
The tab is located inside the firebox. Can a new tab be brazed to existing cast by brazing using a piece of cast and melting the two together?

[Iron Falcon 72]

I am restoring an old cast iron stove. One of the tabs that hold the two sections together is missing. It is a U shaped tab that holds a screw.
The tab is located inside the firebox. Can a new tab be brazed to existing cast by brazing using a piece of cast and melting the two together?

Cast iron can be brazed or it can be OA welded with the proper filler rod or it can be arcwelded with the proper rod. It is not for the faint of heart.
If there is enough beef in the area you might be able to drill and tap holes to bolt another tab in. How much stress is there on the tabs?
Check YouTube for some videos and do a general Google for cast iron repair.

[arftist]

I am restoring an old cast iron stove. One of the tabs that hold the two sections together is missing. It is a U shaped tab that holds a screw.
The tab is located inside the firebox. Can a new tab be brazed to existing cast by brazing using a piece of cast and melting the two together?

It can be torch welded using a cast iron welding rod. It can't be brazed because brazing requires a brass or bronze filler rod. The easiest fix is arc welding with a nickel rod. If you don't have an arc welder then the oxy-ace process with the cast iron rod will work. With either process, preheat, post heat and slow cooling is important. I often bury just welded cast iron pieces in a barrel of wood ashes that I keep for this purpose. Dry sand, lime, and even fiberglass insulation will work, though the fiberglass will burn a little and stinks.

Whatever you do, do not use brazing or bronze welding in a high heat area such as a wood stove.

[BIGGUNDOCTOR]

I have brazed cast, but I prefer to arc weld it, if it can be. Not all cast iron is weldable, so it ends up being brazed. I have moved away from the nickle rods such as E99. I use other rods that generally cost in the $50 per pound range, and have a good color match. Haven't bought any in some time, as I had some that came in from auctions. The higher price rods run a lot smoother, and have worked much better for me. As stated before you pre heat to too hot to touch, use short stringer beads that you peen while they are cooling, then post heat followed by a slow (overnight) cooling in wood ashes. The problem with cast iron is the weld cools faster than the cast which pulls it away from the cast. Peening spreads the weld keeping it intact. I use a straight line needle scaler to peen with. On the wood stove you will also be dealing with expansion, and contraction while it is being used, which may cause some problems.

[Larry H]

Everyone covered it above, I weld a lot of cast iron. clean parts well, clamp parts in position, heat to red heat, weld then reheat again and peen while cooling, use a low temp.because the parts are very soft. this has never failed me

[Dragons lair]

Have brazed several stoves. If the stove or exhaust header gets even close to melting
you have a bigger problem. I prefer brass for the thermal cycle of the stove.
Ken.

[beth]

can anyone just go over what you mean by peening the weld? thanks ive never welded cast but have certainly seen people mess it up....

[HWHII]

Some people out there might have a hard time believeing this but besides using a nickle electrode for stick welding cast an E7018 electrode works very well with no preheat. This practice for repair is even sugested as a repair procedure in " Metals And How To Weld Them " put out by the John F. Lincoln Arc Welding Foundation ( Lincoln Electric ).

[beth]

can anyone just go over what you mean by peening the weld? thanks ive never welded cast but have certainly seen people mess it up....

[beth]

oops? not sure wot happened there...... :unsure:

[jeremy k]

can anyone just go over what you mean by peening the weld? thanks ive never welded cast but have certainly seen people mess it up....

Beth - Peening a weld is when you hammer the weld with a small ball tipped hammer similar to a chipping hammer - what the process does is help to combat the shrinkage of the weld as it cools - which when working cast can cause enough stress to crack the area next to the weld. Just after welding a small section - one peens the weld to expand the weld (same as a fullering technique). Keep in mind that one can over peen also - it's like most things after doing it many times - personal experience/fine line. You just are triing to keep the shrinkage/peening balanced to keep from having stress during cooling. - JK

[BIGGUNDOCTOR]

Hey Beth, I guess you didn't fully read my post above

As stated the weld cools faster than the cast does which pulls it away from the welded edge. I use an industrial inline needle scaler to spread the weld out. I have found this to be the best method for me. I have the scaler draped over my shoulder, so as soon as I stop welding I can grab it and peen the weld. The multiple needles work the entire weld more evenly, and completely than a hammer does. It also smooths out the welded area, while clearing all of the slag. With method, and good rod, I have repaired exhaust manifolds, a lathe base, table saw frame, and various other machinery parts.

Problems can arise when poor grades of cast iron are used, or if the cast iron has a high amount of graphite. It was generally accepted also to do the final weld prep with a burr on a die grinder, or filing, to minimize smearing the graphite over the weld preps like a grinding wheel can.

[jeremy k]

Big Gun - you have a good description of the process - I've done that also when a needle scaler is available. JK

[arftist]

Have brazed several stoves. If the stove or exhaust header gets even close to melting
you have a bigger problem. I prefer brass for the thermal cycle of the stove.
Ken.

Ever gotten a stove red hot unintentionally? It happens sometimes. The tabs the original poster mentioned are likely inside the stove as well, where the brass could readily melt.

[Francis Trez Cole]

I have good luck with the nickle rod get the one you can machine pre heat and cool in perlite.

[beth]

thankyou jk - and big gun you did explain i was not sure what the needle thing was so i thought id just ask - it is all beautifully clear now :)

[BIGGUNDOCTOR]

As to the needle scaler. I found one that is an industrial inline model that has some power to it, and made in the States. I have also used it to texture surfaces. I repaired a buggy part that had some all over pitting from 100 years of exposure to the elements. When I was done welding it I ran the needle scaler all over the ground weld. The dimples blended in so perfectly with the pitting that he customer could not tell where it was repaired. Noisy, but a good tool to have around.

[Mainely,Bob]

Hey Biggun,have you pulled that needle scaler apart yet?
My CP has a way to release the hammer and replace it with other tools.One of my buddies removes the needle assembly, snaps in a polished hammer,clamps the remainder in a home made frame and uses it as a pneumatic planishing hammer.
I`m betting an inventive guy like you could find at least a hundred different ways to use it. :D

[BIGGUNDOCTOR]

I haven't had to pull mine apart yet, but I do know that some have the capabilities to power other tips such as chisels.

I have tons of tools, and tons of ideas,just don't have tons of time at the moment. The 200 mile commute everyday doesn't help, at least I am getting paid well.