machining 1045 steel after welding

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Hey all, quick question.Our machine shop thru no fault of their own, messed up turning a 8" longtaper on a 6" dia piece of 1045 normailized steel, it's 0.004 too small on the small end and correct on the large, from 6" down to 4" approximately.Question, from what I've read and found on line it's easily weldable using low hydrogen rods being on the high end of medium carbon steel, pre, during and post heat being required. What will the machining be like once it's done, or will it even be machinable, again from what I've read yes it will be but I'd like some real work experience. We'd like to salvage this shaft since it's worth $11K :-) ......Mike
Reply:Can you have this 6" diameter piece of steel annealed(normalized), after you build up the diameter of the taper at the narrow end?  If so, then it should machine just like it did when you started.  If the part is too big to anneal, then you can still machine the weld build up.  It'll machine more like 1020 steel than 1045, because of dilution.Realize that when you build up the missing material, you'll have some dilution(mixing) of the weld metal with the base metal.  So the properties will be some "average" of the two materials.If this piece sees subsequent heat treatment(induction hardening, or case hardening for example), that welded layer won't harden like the rest of the shaft.  This may or may not be important.  It depends on what the ultimate purpose of the part. Just something to think about before you jump into welding the part.Benson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector
Reply:Thanks for the reply.Yes it can be normalized after the repair, simple explanation it's a drive shaft for a ferry leg on one of our ferries, it's roughly 3' long with a major diameter of 8"± with multiple steps/diameters for bearings seals etc.I'm waiting to see what the powers to be have to say wether to fix it or start new.....Mike
Reply:Originally Posted by mrmikeyWe'd like to salvage this shaft since it's worth $11K :-) ......Mike
Reply:Matt,just a quick question for my own benefit.  The OP mentioned that the end of the shaft is 0.004" undersize.  Given this, would you still recommend a two pass weld if he uses E7018?  Is this to get some tempering of the weld deposit?  The reason I suggested normalizing after welding is that I figured the heat input from welding would distort and harden the weld deposit(due to some carbon pickup from the base material) and the HAZ.  It seems to me that you'd have to do something to restore the machinability so you could easily turn the shaft back down to the proper diameter.  Or is the hassle of machining the shaft in a hardened state the best compromise? I agree with your comment that a normalizing heat treatment would likely throw off the rest of the dimensions on the shaft. I wasn't imagining a part as large and complex as the OP later described when I made the suggestion.Benson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector
Reply:Can you take it to another shop that can spray weld the part then grind to size with a tool post grinder in a lathe. .004" isn't much. Or if other tolerances allow can you shorten the shaft at the small end and re machine the taper.  Depending on the angle of the taper you could be up to size in a short distance.   Just guessing with out seeing the part. Dan
Reply:Originally Posted by A_DAB_will_doMatt,just a quick question for my own benefit.  The OP mentioned that the end of the shaft is 0.004" undersize.  Given this, would you still recommend a two pass weld if he uses E7018?  Is this to get some tempering of the weld deposit?
Reply:Thanks Matt.Benson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector
Reply:Rather than deal with large areas of welded surface,hardening and such I'm wondering if the shaft ;A) has been cut to length yet?B) Can it be lengthened at the large end and just have the proper taper cut and then move the bearing stepping down?GizzmoSyncrowave 250 CK aircooled tig
Reply:A) has been cut to length yet?
Reply:Originally Posted by mrmikeyNope, it's a very intricate combination of steps, threads and tapers, the position of one dependant on a few others. If it's still in the shop I'll get a pic tomorrow, it seems as if the higher ups are leaning toward scrapping it....Mike
Reply:did the shop prove the taper by removing the shaft and checking over pins with gage blocks before final turn or just use a gage of some sort while in the machine
Reply:hers a pic Attached Images
Reply:Just my observation. The issue is whether the diameter can be remachined? Could you not preheat, tig it, and send it out for grind? I have had plenty of shaft repairs that I have sent down the street to my tool grinder for reclaiming diameters. All in all this type of repair would cost a few hundred bucks.Weld like a "WELDOR", not a wel-"DERR" MillerDynasty700DX,Dynasty350DX4ea,Dynasty200DX,Li  ncolnSW200-2ea.,MillerMatic350P,MillerMatic200w/spoolgun,MKCobraMig260,Lincoln SP-170T,PlasmaCam/Hypertherm1250,HFProTig2ea,MigMax1ea.
Reply:All in all this type of repair would cost a few hundred bucks.
Reply:Originally Posted by mrmikeyI agree, the powers that be have decided to scrap it.....Mike
Reply:Originally Posted by mrmikeyI agree, the powers that be have decided to scrap it.....Mike
Reply:That is a nice looking buildup/reclaim job. Had we done it, it would have been all freehand....Mike
Reply:Originally Posted by DanD78Can you take it to another shop that can spray weld the part then grind to size with a tool post grinder in a lathe. .004" isn't much. Or if other tolerances allow can you shorten the shaft at the small end and re machine the taper.  Depending on the angle of the taper you could be up to size in a short distance.   Just guessing with out seeing the part. Dan