Astro_Al Posted January 20, 2009 Share Posted January 20, 2009 Hi guys, I need to fix up a cast iron lump that is cracked in several places - about 1/2" thick, poss more, and several feet of welds to lay down. I need to do this properly, so I'm thinking drill a hole at the end of each crack, grind / clean out the crack, preheat with a propane torch and then burn in some nickel cored arc rods. Should I attempt to slow post weld cooling? If so, how, its about 3 foot square and 18" high... Lastly, does anyone have a small quantity of cast rods I can buy? I can't bring myself to pay 250 quid for a box??? Cheers, Al. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted January 20, 2009 Share Posted January 20, 2009 Sounds hefty, is the the cig lighter socket from the Mog? Quote Link to comment Share on other sites More sharing options...
Astro_Al Posted January 20, 2009 Author Share Posted January 20, 2009 Nah - rear view mirror, John. Needs to be hefty as the glass is 12 feet thick. Quote Link to comment Share on other sites More sharing options...
dollythelw Posted January 20, 2009 Share Posted January 20, 2009 ..clean out the crack.. fnarrr what is it and are you sure its cast iron and not cast steel Al? Quote Link to comment Share on other sites More sharing options...
Astro_Al Posted January 20, 2009 Author Share Posted January 20, 2009 Yeah, pretty sure. Its from 1870 and sparks like iron... Al. Quote Link to comment Share on other sites More sharing options...
dollythelw Posted January 20, 2009 Share Posted January 20, 2009 are the welds structural? or just tidying up? Quote Link to comment Share on other sites More sharing options...
Astro_Al Posted January 20, 2009 Author Share Posted January 20, 2009 Structural, but only really it's own weight (not insignificant!). The main prob is that I want to avoid the normal cracking on cooling when fudging it with the wrong filler as it'll see some significant cyclic thermal stresses that I think could see it cracking again in time... Al Quote Link to comment Share on other sites More sharing options...
dollythelw Posted January 20, 2009 Share Posted January 20, 2009 its must be a secret thing so I wont ask again if you dont want to stump up for groovy rods you can be bodgy and try using 309 stainless, a lot of preheat, peen and sloooow cool with blankets - it will end up marginally more brittle than a brittle thing though for some light reading on the subject try these (courtesy of TWI library); C.L.M.Cottrell, 'Welding cast irons', published by TWI, Abington, Cambridge, UK, 1986 and available from Woodhead Publishing, Abington, Cambridge, UK. e-mail: sales@woodhead-publishing.com ISBN 0 85300 176 6 Guide for Welding Iron Castings - ANSI/AWS D11.2-89, American Welding Society, Miami, Florida, USA. e-mail: info@aws.org ISBN 0 87171 295 4 Quote Link to comment Share on other sites More sharing options...
Astro_Al Posted January 20, 2009 Author Share Posted January 20, 2009 Yeah thanks Jez, thats exactly the issue I'm having. My favoured fudge was to mig it with 309 stainless (I could tig it I guess?). I have the fillers for doing it either way IIRC. I found a kilo of cast rods (nickel) for 60 quid, so we are getting closer! Hmmm, what to do... No time for books (I've never said THAT before!), I need it done this week! Al. Quote Link to comment Share on other sites More sharing options...
dollythelw Posted January 20, 2009 Share Posted January 20, 2009 pump action poop pistol will be easier when the workpiece is nice and warm Quote Link to comment Share on other sites More sharing options...
steve_d Posted January 20, 2009 Share Posted January 20, 2009 pump action poop pistol.... Sorry, have to ask....possibly a foreign language. Steve Quote Link to comment Share on other sites More sharing options...
smo Posted January 20, 2009 Share Posted January 20, 2009 Sorry, have to ask....possibly a foreign language.Steve MIG welder Quote Link to comment Share on other sites More sharing options...
Astro_Al Posted January 20, 2009 Author Share Posted January 20, 2009 Yeah, I was going to pre-heat with propane either way - and possibly post-heat for a gentle come-down too, since I'd need a lot of sand / blankets to cover this thing effectively... Any tips on peening? The jury's still out on this so any more inputs much appreciated! Al. Quote Link to comment Share on other sites More sharing options...
dollythelw Posted January 20, 2009 Share Posted January 20, 2009 I have a nice needle gun for post weld peening but probably best ask your jury's opinion Im old Quote Link to comment Share on other sites More sharing options...
B reg 90 Posted January 20, 2009 Share Posted January 20, 2009 Have you considered metal stitching? No heat, much reduced risk of subsequent cracking etc. Try searching for metalock on google. We use it at work (oil refinery) for pump casings, recip compressor crank cases, etc. Adrian Quote Link to comment Share on other sites More sharing options...
Astro_Al Posted January 20, 2009 Author Share Posted January 20, 2009 The metal will be subject to serious thermal stress. I need to stop crack propagation and I think I need to get some weld in there to do that. The problem is its easy to see the gaping part of the cracks, but the get narrower and narrower until you can no longer see them, but they are still there, so drilling a hole at the 'end' might well be 50% luck... Tricky, this one. Al. Quote Link to comment Share on other sites More sharing options...
bishbosh Posted January 20, 2009 Share Posted January 20, 2009 Al, Don't discount the Metalok solution on strength grounds - we have used it to great effect on bridges (Grade 1 listed 1816 vintage) for structural repairs. Won't be any good if you need a gas tight seal though..... Quote Link to comment Share on other sites More sharing options...
smo Posted January 20, 2009 Share Posted January 20, 2009 If they use it for the oil industry in pump and compressor casings it cant be that bad!! (metal stitching that is) As for stopping the fracture drilling the ends works on aircraft wing fractures on planes that are still in service, so in theory if you can find the end youll stop the fracture so i'd get hunting al!!! Quote Link to comment Share on other sites More sharing options...
Turbocharger Posted January 20, 2009 Share Posted January 20, 2009 a kilo of cast rods If they can cast the rods, why don't the cast the original thing out of that material? Quote Link to comment Share on other sites More sharing options...
white90 Posted January 20, 2009 Share Posted January 20, 2009 What is it you are repairing then? a Heater for the workshop? Quote Link to comment Share on other sites More sharing options...
B reg 90 Posted January 21, 2009 Share Posted January 21, 2009 If you want to find the end of the crack you need to NDT it. Dye Penitrant testing is possible on a DIY basis. You then know that you are drilling in the right place to arrest the crack. This may be enough to stop it propagating. Welding cast iron is something that the welding engineers at work shudder over. To higher risk of cracking as part of the welding process, cracking due to residual stress when it has cooled, failure of welds in the future. Tell them that you want to metal stitch it and they breath a sigh of releilf. It's a good repair that I would consider 1st before looking at welding. At the end of the day LLOYDs shipping insurab=nc approve the process for use on ships - stitching together crank cases you can party inside they are so big. So it's not a black art. However we don't know what you are trying to repair, what stresses it will see and so on. Adrian Quote Link to comment Share on other sites More sharing options...
steve_d Posted January 21, 2009 Share Posted January 21, 2009 All this fuss over a gas BBQ. Steve Quote Link to comment Share on other sites More sharing options...
Astro_Al Posted January 21, 2009 Author Share Posted January 21, 2009 Oooh! So close! Just scale it up a bit... If its any consolation, the only other one of these I've seen (this specific 'model') was out in a garden being used as a BBQ! It seemed a bit/lot OT so I was trying not to bring the whole 'what is' Q into it. Al. Quote Link to comment Share on other sites More sharing options...
dollythelw Posted January 21, 2009 Share Posted January 21, 2009 but it would have made answering the question sooooooooooooooooooooo much easier let me know if you want to borrow the needle gun Quote Link to comment Share on other sites More sharing options...
Astro_Al Posted January 21, 2009 Author Share Posted January 21, 2009 Yeah, but then how would I get my kicks? Ok, here ya go: Needler might be handy Jez, how about bringing it down with those bits, or I can prob pop over at some point in the next few days? Cheers, Al. P.S. for land rover content, check out the delightful Freelander propshaft in the bottom right, 2nd pic. Oooooh yeeeaaahhhhhh. Quote Link to comment Share on other sites More sharing options...
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