Help with Welding Cast Iron

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I have a Lodge cast iron pizza pan I need to shorten the handles on (flat pan like a griddle).  In other words the handles stick out too far to close the dome on my grill.  The handles are very simple, approx. 1/4" round.  They're obviously cast with the pan, but to describe them they look like 1/4" round stock, bent in a rectangle "U" shape and stuck to the pan sides.  They stick out approx. 1-1/2" from side of the pan, and 4" length to hold with your hands.   I would like to cut them off, shorten them, and weld back on.Any ideas?  I was thinking I'd cut the handles off, shorten them, and weld them back on.  But I understand welding cast iron is tricky.  I'm thinking of pre-heating the cast iron with a oxy/acy torch to 500 F or so, then attach the handles with Lincoln Arc welder using cast iron rods, then continue heating/cooling the cast with oxy/acy until cool.  What do you think?  Thanks,John
Reply:before i say anything, i want you to take this with a grain of salt... what you say sounds good to me. i know you have to pre-heat and post-heat the area when you weld cast iron due to the brittle nature, however, i am not sure of what the temperatures shouldbe before you strike the arc...as far as i would be concerned, since you already have the O/A rig, i'd be more prone to brazing it rather than welding it. CI has a very porous, very brittle nature (obviously) and thus should be take care of when extreme heat levels are applied/removed. brazing uses less heat and is completely applied using a torch, rather than the more focused, higher heat of a welding arc which can cause serious problems (as we all know).now, here comes the kicker... i KNOW that this isn't the right way, and i KNOW that i will be jumped all over for this, but you CAN just weld it with no pre-heat and no post-heat. i am doing it with an exhaust manifold at home now. i hope to finish it up tonight and i will post another thread on it tomorrow (i hope). yes, i hear cracking, but nothing has broken. i am trying to do minimal amounts at a time as to minimize warpage and shrinking, but i am laying enough on there to make a lot of heat in the part and making sure the beads are laying down and creating a good toe. if it was a structural part, i'd say to stay away from doing it any way but the right way... but considering you are just doing it for home use (i'm assuming), you could just weld it and call it good. if you are not worried about aesthetics, you could always just make other handles out of something other than cast iron (MS perhaps?) and just tack them on. once again, i am assuming here, but it's can't be that large, and i doubt you are lifting anything heavy on the griddle.hope that helps.Later,Andy
Reply:I would only work on the handles.  stay away from the pan as far as you can.  Cut the outside flush, cut off as much as you need and weld back on to the stubs.  Then you won't be welding on the pan at all. Torch weld, braze, Tig or stick weld if you have to.  I would use a nickel rod.I was once told to put a piece of wood 2X4 on the piece being preheated.  When the wood chars, start welding.  I don't even think you will need preheat as long as you are not welding on the pan.Aczeller, I have cold welded manifolds and heated them red.  It works much better when I heat them red.  I bury them in speedi dry when done.DavidLast edited by David R; 03-12-2008 at 02:47 PM.Real world weldin.  When I grow up I want to be a tig weldor.
Reply:Thanks guys.  We looked up the melting point of cast iron, for o/a welding; of course we all know cast iron is not equal.  Anyway seems the melting point is around 2500 degrees F.  Will a torch heat that hot to weld?  I like the brazing idea with O/A.  There's definitely not going to be enough weight on the pan to worry much about strength.  Is there a special brazing rod for brazing cast iron?  Or could I braze using the arc welding rods I have for cast iron.  I forget what they're called; other than EXPENSIVE!  $25 a pound, plus some stupid sur-charge!!   Yikes.  No wonder welding is expensive. And I definitely like the cut as far away from the pan idea.  Leaving knobs on the side of pan to weld to.  Great idea; Thanks David.
Reply:this might be a good job for braze welding, If the pan will not be subjected to cooking temps over 500*. The braze welding will leave brass contrasting w the iron, if you want the part to be all one color then fusion welding is suggested. ( stuff I paraphrased from the book) Im not sure that the arc welding rods would work for brazing since brazing takes place at much lower temps than fusion welding. Brass brazing rod would probably work well. Good luck
Reply:What happens if the pan gets over 500 F.?  Because it definitely does/will.  The best pizza is done about 750 F.
Reply:umm... the brazing may start to melt... think of brazing like soldering, but better. the heat from the torch actually opens the pores within the metal, and the brazing rod melts, gets into the pores, and bonds as everything cools. a good neutral flame on an O/A torch will get to about 2650 degrees (i think). it may be 5600, but i'm not sure. i'd bet closer to 2600. anyway, you can definately weld with o/a... it's actuall the best practice for TIG, but it depends on how large/thick the cast iron is. cast iron works very well at disipating heat over the entire surface.brazing DOES require a special rod tho. flux coated is available, as well as bare, but you need to heat the bare wire, then dip it in borax to coat it. the borax acts as a flux. try Home depot for the rod if you are only going to need a little bit. it's not worth having an entire pound laying in the shop if you aren't going to use it. for something the size that you are talking (4 connections at 1/4" each), i doubt you'll use even half a rod.Later,Andy
Reply:Hell I already bought a pound!  Of the expensive stuff!  I knew I wouldn't use a pound on the pan, but figured what the heck buy now have it for later.  Nice trick with the borax; thanks.
Reply:no problem... glad to help. i'm not really sure if the flux is really REQUIRED, but it'd be interesting to see. maybe after i get an o/a setup and some rod, i'll try it, but for now, i can't. my instructor really pushed it onus, but never really told us why.Later,Andy
Reply:David told you right. Stay off the pan. I would probably just braze it and since the handles aren't in tension you should be all right whichever method you use. Brazing rod is not brass. It is manganese bronze and is actually stronger than the cast iron. The melting point of brazing rod is pretty high though I don't remember for sure, around 1850 degrees F. I think. You won't get it hot enough to bother it in a grill. I just hate to mess with cast iron.
Reply:I sometimes knock the flux off the stick, clean it up and tig with the rod as filler.  It gives nice control of the heat. No other flux needed.To torch weld it with nickel rod, you need cast iron flux.  Its red is all I can rember.  I have a couple of cans of it.  Lasts for ever.You can braze it with tig too, but don't use any flux.DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:The temperature of the O/A flame runs from 5,800 to 6,000 degrees,F, depending on the ratio of oxygen to acetylene. I did remember that. Also, if you will use a slightly oxidizing flame when brazing you will have less porosity. The key word is slightly.
Reply:I missed a key. It is 6,300 degrees.
Reply:its  made for  the oven...preheat it there.....leave oven on.....take out  pan..weld it  braze it,  what  ever  you are  going  to do...put  right  back in the oven and  then shut oven off... leave  to cool slowly....when cooled  it  should be  good
Reply:Brazing will hold up fine or you can get some nickel welding rod.It will take more than 500 degrees to melt brazing rod since it is not pure brass.Camonut
Reply:Okay, I cut the handles off last night, leaving nubs to weld to.  Then fried potatoes in it on the grill.  I think I'll leave it like it is, with the nubs, I kinda like it that way.  The only thing I'll do is round them.  For handling the pan they worked great.  Also, the handle legs weren't exactly 90 degree elbos, so the part I cut off, if I remove a 1/4" of material to shorten them (distance from pan), they won't be wide enough to stick onto the legs!!  But, again I like the nubs.  Plus it fits great on the grill; which is what I wanted.  Thanks for all your help,You guys are great.John