Cast Iron Question

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I need some advice from the cast iron experts. I have a spoked sprocket that is broken and not sure which procedure to use, whether to heat it completely and braze it, use nickel with complete heat, or spot it a little at a time with nickel and keep it cool.I do cast every once and a while, but this sprocket with spokes looks like a crack nightmare. Any recommendations appreciated.Here is a picture of the sprocket, not that good with cell phone, it's about eight inches in diameter. Quarter for size ref. Attached ImagesTrailblazer 302Hobart Stickmate AC/DCLincoln SP 135 TSmith torchSpoolmatic 30A
Reply:The break at 9:00 seems recent..The other 2 have rust in/on them so it seems like they have been cracked for some time...Myself?I would give myself a good land to weld on by grinding the 2 parts to a small "V" and just hit them with the TIG and some 309..Nope.... I would not pre heat or post heat..I have had good results by going slow and easy..But some castings are better than others......zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:I'd probably clamp it together then V out only the middle break and weld it up. This leaves the other 2 breaks to hold it square. V out and weld up the other 2 one at a time after. If you grind everything from the begining there's nothing to locate the parts and you're increasing the chance of everything coming out crooked. Would use 309L stainless as I've had better luck with it than Ni-55. I wouldn't bother with Pre/post heating either.Welding/Fab Pics: www.UtahWeld.com
Reply:Thanks for the advice. Zap, The only problem I have is I am just beginning to tig and don't know whether My capabilities are where I should tackle this with tig or not.  I'm using my tig scratch start running off of my Hobart buzz box or my Trailblazer, right now I'm set up with 3/32 tungstenI just went out to the shop and checked, the tig rod I have is 308, I also have some 309 in stick rod.Last edited by shortarc; 06-05-2012 at 05:09 PM.Trailblazer 302Hobart Stickmate AC/DCLincoln SP 135 TSmith torchSpoolmatic 30A
Reply:Pick up a used copy of the Union Carbide/Linde gas welding handbook.  They cover stuff like this repair well.  I got a pristine copy from a used bookseller for about $6. delivered.
Reply:I also advocate the 309 rod. I did some on sunday with pretty good results.Local 597
Reply:+1 for tig with 309L and vee out the crack. I would also drill and pin it before welding. Drill on an angle and drive in a .125 roll pin, helps hold it true for welding and adds a lot of strength to the repair.
Reply:Well in the morning I'm going to strip the flux off of a couple of stick rods I have and give it a go. I'll post pictures of the outcome tomorrow.I would get the regular tig rod but it's a 30mile drive to my closest LWS.Thanks everyone for the advice and help.Trailblazer 302Hobart Stickmate AC/DCLincoln SP 135 TSmith torchSpoolmatic 30A
Reply:Originally Posted by shortarcWell in the morning I'm going to strip the flux off of a couple of stick rods I have and give it a go.
Reply:PM SentTrailblazer 302Hobart Stickmate AC/DCLincoln SP 135 TSmith torchSpoolmatic 30A
Reply:Oldemdum:Can you give me the ISBN number for the book or post a picture of the front cover please.I'd like to find a copy.Thanks.GlennSign on East Texas payphone: Calls to God 40 cents......it's a local call...
Reply:Originally Posted by zapsterThe break at 9:00 seems recent..The other 2 have rust in/on them so it seems like they have been cracked for some time...Myself?I would give myself a good land to weld on by grinding the 2 parts to a small "V" and just hit them with the TIG and some 309..Nope.... I would not pre heat or post heat..I have had good results by going slow and easy..But some castings are better than others......zap!
Reply:Originally Posted by montgoc3309 rather than a high nickel rod?  What are your thoughts on the two?  I'm curious, as I get a decent amount of cast repairs and typically TIG it with NI-99 and it works pretty well, but if 309 works better, I'm up for trying it!
Reply:Originally Posted by zapsterNickle rod costs mega $$$$ and you can only buy it in 10 lb tubes..Cost VS free...zap!
Reply:How about cast iron rod and oxyacetylene? Preheat in the right places and you should be able to make the welded spot shrink as much as the preheated spots that otherwise would prevent the weld to shrink as it cools down. On the other hand, that looks relatively small, you could heat the entire piece pretty easy.Last edited by G-son; 06-06-2012 at 10:39 AM.
Reply:i would  bevel it then media blast it then preheat it then use some ni55 tig it up then post heat it ohh and peen it after each lil beadNi99 is for thin cast Ni55 is for thick casti just had some train castings come into the shop that needed welded up the Ni55 has good ductilitythe train casting was grey cast Attached ImagesLast edited by WeldorWes; 06-06-2012 at 05:25 PM.Miller Xmt 350Lincoln Ln-25Ahp 200xSmith Gas Mixer AR/HTig is my Kung FuThrowing down dimes and weaving aboutInstagram http://instagram.com/[email protected]
Reply:Originally Posted by WeldingWookiei would  bevel it then media blast it then preheat it then use some ni55 tig it up then post heat it ohh and peen it after each lil beadNi99 is for thin cast Ni55 is for thick casti just had some train castings come into the shop that needed welded up the Ni55 has good ductilitythe train casting was grey cast
Reply:If that sprocket does not encounter high temperatures, bronze would be a good option (you could TIG braze it using something like Aluminum Bronze A2), and it is much cheaper than NI-ROD, yet less likely to cause cracks than 309. (which I believe should only be used as a last resort... e.g., you don't care about the part being welded very much, and it's all that you have on hand.)Just my 2c... based on testing all of the above and welding cold.  Others may have different opinions, there are no "hard" rules with it comes to repairing cast iron, there are a variety of different techniques, with pros and cons.PS - you can buy NI-ROD in 1# increments, if you know the right places to shop at.  If you have a good local welding supply, they may sell it to you by the stick.  It's definitely spendy stuff to buy though, no matter how you cut it!
Reply:Originally Posted by castweldThat looks good, was it fun?Peter
Reply:Cant really comment on the 309 for your repair as Zap recommended as i have not used that on castMiller Xmt 350Lincoln Ln-25Ahp 200xSmith Gas Mixer AR/HTig is my Kung FuThrowing down dimes and weaving aboutInstagram http://instagram.com/[email protected]
Reply:Originally Posted by zapsterNickle rod costs mega $$$$ and you can only buy it in 10 lb tubes..Cost VS free...zap!
Reply:309 does not have enough nickel to get into a low coefficient of thermal expansion mode, which is likely what helps NI-ROD weld cast iron (when performed "cold", without preheating) without cracking.You need over 20% to get into a low coefficient of thermal expansion.  It seems to "peak" at 36% nickel content in a nickel-iron alloy, such as invar:http://en.wikipedia.org/wiki/InvarBut as you add more nickel than 36%, it also raises the temperature at which the alloy has low thermal expansion.source:http://www.cartech.com/techarticles.aspx?id=1664Also, when welding cast with NI-ROD, the 55% nickel may be diluted by the cast iron and the weld deposit at least at the weld joint interface, will be less than 55% nickel.  Maybe that gives it low coefficient of thermal expansion right where it is needed to prevent cracking along the interface between weld joint and parent metal.Some Nickel-iron alloys of 52% (pretty close to NI-55's composition of 55%) are used to approximate the thermal expansion characteristics of glass.  I couldn't find much about why 55% nickel was determined to be useful for cast-iron welding, but if anyone has any references about this, please post it, as I'd be curious to know.  Thanks
Reply:Originally Posted by zapsterNickle rod costs mega $$$$ and you can only buy it in 10 lb tubes..Cost VS free...zap!
Reply:Got this thing stuck together. I really hate to post the pictures after seeing some of the smooth welds posted on here but here you go.I guess it went well for the amount of arc time I have using Tig, which is about two hours total, using a Hobart stickmate buzz box and scratch start. Thanks for all the help and suggestions, now to find some cast to practice on with the Tig.A special thanks to Zap.That black spot in the last picture is a sand hole in the casting. This is off an Amish corn binder. Attached ImagesTrailblazer 302Hobart Stickmate AC/DCLincoln SP 135 TSmith torchSpoolmatic 30A
Reply:Seeing that you "Scratch Tigged" it, where was where was your current setting approximately?Thanks!Aprox. 100 ampsTrailblazer 302Hobart Stickmate AC/DCLincoln SP 135 TSmith torchSpoolmatic 30A
Reply:Originally Posted by drujininSeeing that you "Scratch Tigged" it, where was where was your current setting approximately?Thanks!
Reply:LOL!!!I read it 3 times, went back your post, couldn't see the "stutter".  Suddenly I saw it!! I don't think it's the keyboard, I an thinking "hand, eye, brain coordination!