PROBLEM with Cast Iron

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Hi, yesterday I bought a cast iron pot belly stove. It was heavy as hell, three of us could barely move it, and when we went to get it into the truck two of the legs snapped off. I am terribly upset because the stove is gorgeous. Doe anyone have any suggestions on how to fix, weld, braze, these legs back on? ANY HELP WOULD BE MUCH APPRECIATED! Thank you!!
Reply:Picts would help along with what equipment you have to try and do the repair as well as what experience level you have.Castweld here is probably the best with cast iron repairs. He's got dozens of threads on various cast iron repairs. What process he uses depends a lot on the situation..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:Hmmmmm I assume since this is your first post your not familiar with cast?  If this is the case call your local weld shop and start asking questions about who does cast iron repairs........The stuff can be a real PITA  if you go about repairing it the wrong way........  Miller Dynasty 350Twenty Six HammersThree Crow BarsBig Rock
Reply:It's likely you can remove the legs, for ease of transferring to someone who knows what they're doing... I'm going to try a cast iron repair on a vice I've got eventually, but I'm waiting until I have more confidence and have set up for it. The trick, as I understand, is that even a good-looking cast iron weld can be weak and riddled with cracks or stress that leads to cracks. Also, you can burn the carbon out of the cast, weakening it and changing the coefficient of expansion, leading to stress cracks. In any case, it seems sorta hard to do a competent job at, especially since all cast is different. The fact that your stove will be getting hot will add to the potential for stress problems, and that a failure (in your living room with a stove full of burning wood losing a leg) could be tragic... Note that I'm really just parroting what I've learned in my research for my vice repair. Good luck. If it's a current model you might be able to buy legs... Even if it isn't you might be able to adapt some other legs. I see quite a few online.Miller XMT304 CC/CVBernard TIG coolerSSC foot pedal"It's a poor craftsman who blames his tewls toles TOOLS" (!^$#% keyboard)
Reply:pfost,         Cast iron is not as bad to repair as most would lead you to   believe as long as you stay away from any form of arc weld. The  best repair is O/A with cast iron in stick form , and being that you  need it to be cosmetically perfect O/A is the only way to go.   When finished it can be ground to look just like the base material  and is a perfect color match. I repair ex manifolds and other  castings including vises , many of the manifolds are for collector  tractors and need to not show the repair . Check the websites  below . If you want to try to repair send me an email and I'll   coach you through it.       georgeIdealarc 250 , sae 600 lincoln m/g, many torch sets,2 sub arc machines.   5 milling machines,6 lathes,planer , 3 surfacegrinders ,cyl grinder, automotive machine shop. http://www.georgemillermachine.com/ http://www.imageevent.com/gmachine
Reply:George: as I'd said, I'm just repeating what I've heard, so it's interesting to hear of your experience. But I saw a fair number of cracked welds in my research...Do you preheat the entire piece? Do you do a slow cool afterwords? How often do you get cracks?Miller XMT304 CC/CVBernard TIG coolerSSC foot pedal"It's a poor craftsman who blames his tewls toles TOOLS" (!^$#% keyboard)
Reply:George, how's it going?  You make it sound easy, LOL."USMCPOP" First-born son: KIA  Iraq 1/26/05Syncrowave 250 w/ Coolmate 3Dialarc 250, Idealarc 250SP-175 +Firepower TIG 160S (gave the TA 161 STL to the son)Lincwelder AC180C (1952)Victor & Smith O/A torchesMiller spot welder
Reply:Originally Posted by keithwinsGeorge: as I'd said, I'm just repeating what I've heard, so it's interesting to hear of your experience. But I saw a fair number of cracked welds in my research...Do you preheat the entire piece? Do you do a slow cool afterwords? How often do you get cracks?
Reply:It shouldn't be a problem with the right rod, unfortunately that rod is very expensive. UTP makes the 85FN rod that doesn't require preheat or post heat and is very easy to use. It is very important to grind a U groove and not a V groove, don't weld over 1" at a time and peen that inch until all flux is gone. I've used these rods for 25 years or so and with great success. The bad news is that these rods are $84 a pound and 10# is a minimum purchase.
Reply:First, thanks Makoman1860 and Bob, you did clear some things up for me. But I will confess to further confusion. Cast Iron has, I believe, up to about 4% Carbon and 3% Silicon. Makoman disparages "using some form of nickel based brazing/welding material" and argues for using "real iron filler not that shade tree nickel based farm rod". But Bob suggests UTP 85FN which is 45% Nickel, and much of the cast iron repair rod I see is either 55% or 99% nickel. In fact, every welding rod I found that is designed for cast iron, has a lot of Nickel in it. I see one, Certainium 70, that claims excellent color matching, sort of like George mentioned. He didn't say what he uses.I learned a bit about the rather complicated structure of cast iron in my research, which is part of what can make it crack-prone. There is apparently a sweet spot of prewarming and postwarming: it has to be above 450 or 500F, but below 1000F, at which point the internal structure changes in some manner. I don't remember the specifics. I don't know whether most people get the entire part to 500F: in the case of my vice, even after I take it apart that's a fairly big piece, and a lot of heat.I'd be very interested to hear what specific rods and/or processes people use, since hands-on experience has a lot of value to my mind.BTW: online, at least, you can buy the UTP 85FN by the pound, min. quantity one pound, but it's $97...KeithMiller XMT304 CC/CVBernard TIG coolerSSC foot pedal"It's a poor craftsman who blames his tewls toles TOOLS" (!^$#% keyboard)
Reply:Keith,         Slow preheat in fire brick enclosure with gas fire, heat to  glow 1000 to 1200 deg , weld while maintaining the heat , post  heat to 1500 and hold for 15 minutes . Take at least 30 minutes  to cool to 1200 and slow cool on down in temp.   As for cracking , almost always if it cracks it was not hot enough, needed more preheat. If not machinable when finished , it cooled from 1500 to 1200 too quickly.  There is no such thing as keeping the work cool while welding, the temp of the arc is several thousand deg and it heats the area around the weld quite hot , the rapid cooling from the surrounding cool material is what causes the cracking.      georgeIdealarc 250 , sae 600 lincoln m/g, many torch sets,2 sub arc machines.   5 milling machines,6 lathes,planer , 3 surfacegrinders ,cyl grinder, automotive machine shop. http://www.georgemillermachine.com/ http://www.imageevent.com/gmachine
Reply:Another curious thing: UTP on their web site lists all their cast iron products as only MMA (Stick) compatible: specifically not gas. They do have one for MIG.http://www.utpsales.com.au/Miller XMT304 CC/CVBernard TIG coolerSSC foot pedal"It's a poor craftsman who blames his tewls toles TOOLS" (!^$#% keyboard)
Reply:George: Thanks!!! Wow, so you really preheat that thing. VERY helpful to know. That was really helpful, especially your distinction between cracking/preheat and hardening/cooling rate.What rods do you use? From your earlier post, it seems you use O/A: do you just use a regular MMA/GMAW stick for that (sorry, I don't have O/A experience yet). Thanks again, that was really helpful.Miller XMT304 CC/CVBernard TIG coolerSSC foot pedal"It's a poor craftsman who blames his tewls toles TOOLS" (!^$#% keyboard)
Reply:Keith,        You posted while I was typing.  I do NOT use arc weld , I use   cast iron in stick form and a can of superior flux with O/A torch.   with O/A you can match the original material.       Send me an email if you want to chat.      georgeIdealarc 250 , sae 600 lincoln m/g, many torch sets,2 sub arc machines.   5 milling machines,6 lathes,planer , 3 surfacegrinders ,cyl grinder, automotive machine shop. http://www.georgemillermachine.com/ http://www.imageevent.com/gmachine
Reply:Hi George, I'd love to chat but I think it's so helpful to get this stuff into the forum, so I can search it next week when I totally forget what you've said!When you say "cast iron in stick form", what do you mean? I can't find any such thing, unless I'm just thinking about this wrong. Thanks for the flux clarification: just to be completely clear, I notice that Superior makes a cast iron-specific flux, is that what you use?KeithMiller XMT304 CC/CVBernard TIG coolerSSC foot pedal"It's a poor craftsman who blames his tewls toles TOOLS" (!^$#% keyboard)
Reply:Keith, The filler is literally cast iron. Kastweld 111 is a popular brand, and is of " traditional chemistry". The rods are literally individually cast sticks of iron, doped with silicon. Harris, Aufhauser, Esab and others offer the same material. Small quantities can be had from TM technologies.
Reply:Thanks Makoman, that's exactly what I'd missed. I think Harris is the manufacturer of Kastweld, which I can't find any source for yet (it's not on TM Technologies site, but I can talk with them). I don't see anything on Esab's site about cast iron.Aufheiser has an interesting page on cast iron welding, here:http://www.brazing.com/techguide/pro.../cast_iron.aspIt mostly talks about using NI55 and NI99 with arc welding, but does mention their pure cast iron rod, and basically confirms what George has to say about it. The NI55/99 advantage appears to mostly consist of not having to preheat/post-warm-down, but at the cost, I think, of in increased chance of cracking. The site also mentions O/A and their traditional cast iron rod, RCI:http://www.brazing.com/Pdf/castiron/RCI.pdfHere's what they have to say about it:Oxy-acetylene welding of cast ironsFor successful oxy fusion welding, it is essential that the part be pre-heated to a dull, red heat (approximately 650°C). A neutral or slightly reducing flame should be used with welding tips of medium or high flame velocity. The temperatures should be maintained during welding. As with Shielded Metal Arc Welding preparation it is necessary to use a furnace to ensure even heating of large castings. It is important that the casting be protected from draught during welding and provision should be made to ensure that the required preheat is maintained. It is important to avoid sudden chilling of the casting otherwise white cast iron may be produced which is very hard and brittle. This may cause cracking or make subsequent matching impossible.Oxy welding is suitable for grey cast irons with an AWS A5.15 RCI (Aufhauser RCI), RCI-A type electrode and should used with a suitable flux such as Aufhauser Cast Iron Flux.Austenitic cast irons can only be oxy welded with an AWS RCI-B type consumable.Miller XMT304 CC/CVBernard TIG coolerSSC foot pedal"It's a poor craftsman who blames his tewls toles TOOLS" (!^$#% keyboard)
Reply:Keith,         Harris brand is the kastweld , but having talked to their engineering dept about the fact that their rod is no longer machinable as welded, they admitted that they no longer make the rod and it comes in from  the far east . Also know a fellow that worked in the last foundry in the US that made the welding rod . The owner died and the foundry closed. They made the rod for harris and airco and many others, all is imported now. I have some rod from harris and airco that is machinable as  welded without normalizing , it is at least 20years old and I save it to use on a large piece that I can't do a proper preheat on.       If you want to learn about O/A welding stay away from any site  that sells arc welding materials , they push arc rod when they know that O/A is a much better process with better results, but it does take more work.    As I said before ,if you want to chat , send me an email with a  phone # and I'll call .  I am a very poor typist (slow ) and I'm not  going to sit here for days trying to explain what would take a few minutes on the phone.     georgeIdealarc 250 , sae 600 lincoln m/g, many torch sets,2 sub arc machines.   5 milling machines,6 lathes,planer , 3 surfacegrinders ,cyl grinder, automotive machine shop. http://www.georgemillermachine.com/ http://www.imageevent.com/gmachine
Reply:By the way , look at the web sites to see what can be done with O/A, It will take the wind out of the arc weld gang's sails . Many of those manifolds are way too thin to touch with an arc.Idealarc 250 , sae 600 lincoln m/g, many torch sets,2 sub arc machines.   5 milling machines,6 lathes,planer , 3 surfacegrinders ,cyl grinder, automotive machine shop. http://www.georgemillermachine.com/ http://www.imageevent.com/gmachine
Reply:Cast iron practice, broke a flange of a old 50cc cylinder and built it back up again with a Henrob O/A torch and cast iron piston rings (from a scrapped Briggs & Stratton lawnmower engine, but anything except modern high performance engines should have cast rings). Limited preheat with the torch, not very serious slow cooling either, would have been ALOT more careful if it was an actual repair and not practice on scrap metal.Still soft and machineable, and according to my hammer, stronger than the original flange (but it broke through the screw hole and I haven't bothered drilling a new one).Tried stainless filler and filler for mild steel on other cast repairs. Miserable failure. O/A and cast iron filler is the only way I'll be welding cast iron as long as it's possible to preheat/slow cool. Stick welding it cool might be an option otherwise, but I'd prefer a repair without any welding at all over that.
Reply:Keith, George is correct about some of the latest fillers not being as nice as they used to be. However they do still work just fine. The last box I bought from aufhauser was really nice,and that was about 3 years ago, havent bought any since as I buy 50lbs at a time. Gotta remember that politics and financials controls what information we see. Companies will always push what makes them more money. They will sit on boards for groups like the AWS and influence what handbooks and textbooks say....all in the name of profit. TM has the material. http://www.tinmantech.com/html/cast_...supplies.php#1
Reply:Thanks again George: you comments about rod availability finally clear things up for me a bit. No wonder it's almost impossible to find. Now I understand the repeated reference to piston rings I've seen, too -- thanks G-Son. I think I finally understand the lay of the land (which I don't confuse with having any actual experience!).KeithMiller XMT304 CC/CVBernard TIG coolerSSC foot pedal"It's a poor craftsman who blames his tewls toles TOOLS" (!^$#% keyboard)
Reply:Look at UTP's cast rod availability. They have more than any other company. They have taken cast welding into the modern age. As I said earlier though, they are expensive. I used my last one yesterday welding on an old IH scout head and exhaust manifold. That one rod made me over a hundred dollars. Do you remember where you seen the 85Fn rods by the pound?
Reply:I just got off the phone with George, who really filled in the missing bits. He's a fount of information.To start, most of the rods you can buy to weld Cast Iron (CI) are stick rods of Nickel compounds, from 45% up to 99%. I know some people are using them and are happy with them, that's all good if it works for you, but I'm not going to talk about them. It seems clear to me that the stress of localized heating of cast iron is often a no-win situation: you might get away with it in a situation where the cast iron can expand and contract without restriction, but otherwise you're likely to get cracks. High operating temperatures increase the chance of problems down the road.CI is a complicated material (as are most metal alloys), with various kinds of micro-crystalline formations and whatnot. It typically has a melting point of around 2000F. An O/A torch burns at more like 6kF, but you easily temper that by adjusting torch position and mix. An arc process has a higher temperature still, but I think the real problem is you can't really temper it: either you have an arc or not. You can try to move fast or slower to spread the heat out some, and closer and further to make a longer/hotter arc or vice-versa, but these are relatively minor adjustments, compared to what you can manage with an O/A torch. The stresses introduced by heating unevenly are what result in cracks. The only way to avoid them is preheating and postcooling: you have to get the part up to 1500F to "normalize" it (what I would call annealing from my glassblowing background, and which is gone into in depth http://steel.keytometals.com/Articles/Art112.htm -- there's a difference between normalizing and annealing that I don't quite understand, and proper annealing is done quite precisely to effect specific changes...George suggested looking at this site, which has a powerpoint presentation that emphasizes the heating/stress points, and argues forcefully for O/A (or non-heating approaches, like stitching), and had tons of other great info: http://locknstitch.com/cast_iron_welding.htm . The link on the bottom shows a workshop that's quite interesting.I'd also recommend looking closely at all the pictures in the links at the bottom of George's signature: they show his construction of a normalizing oven to heat these parts to around 1500F to work on them, and then working on them while keeping them hot. What's notable here is that some of the preheating efforts you might see on the web are just not in the right league: they aren't getting the parts hot enough, they aren't holding them hot, and they aren't controlling the cooling. On the locknstitch site there's also pictures of them constructing an "oven" to heat a huge piece hot enough to fill a gouge.I'm not the first person that George has helped think about these issues: here's a thread on another site that also summarizes what someone else (also on this site, I understand) wrote up:http://www.tractorbynet.com/forums/w...education.htmlAgain, others may have their tried & true methods, and if you're putting back together something that doesn't really matter if it breaks again, then, well, it doesn't really matter. Even if I don't always do things the "right" way, I like to know what it is so I can have some clue of the implications of my improvisations.Hopefully this is helpful to put down in one place... At the very least, I'll probably refer to it next week, when I've forgotten everything I've just learned!Miller XMT304 CC/CVBernard TIG coolerSSC foot pedal"It's a poor craftsman who blames his tewls toles TOOLS" (!^$#% keyboard)
Reply:@ george, I sure had fun looking through your linked pics! The statement about not being able to explain his procedure in a post is similar to my own experience.For the broken stove legs and the vice I'm gonna reach for the Kastweld, you have to stick to the heat rules posted to be successful. The problem doing the OA welding with CI is much the same as stellites and cobalt/chromes IMO. The puddle has a different look and takes practice to get it down. You just can't talk it or type it you gotta do it.Cast iron has different expansion and transformation rates than the non-CI materials often used to join it. More important is that cast is still stiff at very high heat and at 1500-1600F is much stiffer than steel at those temps. So when it grows it squishes the filler around and when it contracts the filler has to be ductile enough to stretch.So when you can't do the furnace thing you have either braze with brass/bronze or one of the nickel/chrome/silicon rods/powders.Ni-rods actually come from 30%ni to 99%ni if you have the lower nickels you better have good sections without sharp corners and such and be able to peen the whole area around the weld quickly. You actually move some iron & put it in compression. It will still have a small section in the parent CI that is what is called "white cast iron", which is pretty much sewage, it's brittle as glass. N99 can be used to weld thin things because it's weak and super ductile but you still get the white iron so any twisting and such will fail at that place. N99 also sucks to weld with, super resistive and prone to overheating the rod...Brazing is safe because of the heat soak. The practice thing and the sticking to good habits and procedure is crucial.A company I worked for years ago once repaired a #4 Cincinnati mill that had been dropped & shattered the back base (the base is the coolant tank). Took about 2 weeks for 2 guys & they had to make some missing pieces from plate. I was impressed when it was all done & painted.Anyway, I'll attach a couple of nut ball fixes with cast iron... First two are a ductile iron part that is bore and face welded with E70-s3 with Co2 shielding and the second two a case that was repaired with NiCrSi powder spray using a Colmonoy torch.Good thread!Matt Attached ImagesMatt,       I also have been spray welding , have both colomonoy and eutectec   systems both hot and cold ,also metco powder and wire spray..   Like your jig mill,makes my 3" lucas look a bit clumsy.       georgeIdealarc 250 , sae 600 lincoln m/g, many torch sets,2 sub arc machines.   5 milling machines,6 lathes,planer , 3 surfacegrinders ,cyl grinder, automotive machine shop. http://www.georgemillermachine.com/ http://www.imageevent.com/gmachine