Stack welds to fix aluminum head?

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I had a bolt break off when tearing down this old cb750 head. It holds a small cam chain guide.   Needless to say the extraction did not go well... After trying a left-handed bit, and breaking an extractor which left a piece lodged in the hole I was forced to grind down the mangled post.    I think I should be able to drill further, tap the hole and use a spacer. But then I started thinking about rebuilding the post by stacking tig beads.Any advise?
Reply:Is the bolt steel? Can you weld to the bolt and unscrew it? It should get hot enough to expand and come out without too much force. At least I would think.I did this with the harbor freight 80amp stock welder a few years back on an aluminum head.Torchmate 2x2 CNC with Flashcut CNC controlsHypertherm Powermax45 Esab ET220i Razorweld 195 MigRazorweld 200ac/dc TigTormach 770, Tormach xstechRazorweld, Vipercut/Vipermig, SSC Foot Pedal Dealer
Reply:Originally Posted by GambleIs the bolt steel? Can you weld to the bolt and unscrew it? It should get hot enough to expand and come out without too much force. At least I would think.I did this with the harbor freight 80amp stock welder a few years back on an aluminum head.
Reply:Many, MANY a bolt broken off below the surface have been extracted by building up with weld (stick, TIG and MIG), a nut welded on and unscrewing the bolt.  Often, a washer is welded on first for protection and larger surface to work with before the nut is welded on.  Very routine and common process.  Just do a search and you'll find a number of threads and posts on the subject.At this point, I would build the area up using TIG and have machined back to dimension and drill/tap a new hole.  Walk in the park for a number of members here with castweld (do a search) being the most popular.MM200 w/Spoolmatic 1Syncrowave 180SDBobcat 225G Plus - LP/NGMUTT Suitcase WirefeederWC-1S/Spoolmatic 1HF-251D-1PakMaster 100XL '68 Red Face Code #6633 projectStar Jet 21-110Save Second Base!
Reply:Hello ncoloqerojr, I'll try to include a couple of photos to show a repair done on an aluminum intake manifold, might give you some idea of "stacking" beads. In your case you would not be using a bolt or anything to keep the center clear and would want to provide a solid build-up to allow for drilling and tapping when you are done. Best regards, Allan Attached Imagesaevald
Reply:Nice work aevald.Miller Maxstar 200 SDPiperliner #10 Gold
Reply:Originally Posted by duaneb55Many, MANY a bolt broken off below the surface have been extracted by building up with weld (stick, TIG and MIG), a nut welded on and unscrewing the bolt.  Often, a washer is welded on first for protection and larger surface to work with before the nut is welded on.  Very routine and common process.  Just do a search and you'll find a number of threads and posts on the subject.At this point, I would build the area up using TIG and have machined back to dimension and drill/tap a new hole.  Walk in the park for a number of members here with castweld (do a search) being the most popular.
Reply:Originally Posted by aevaldHello ncoloqerojr, I'll try to include a couple of photos to show a repair done on an aluminum intake manifold, might give you some idea of "stacking" beads. In your case you would not be using a bolt or anything to keep the center clear and would want to provide a solid build-up to allow for drilling and tapping when you are done. Best regards, Allan
Reply:after you get it done take it to a auto machine shop and have it checked for straightness, on the alum heads they normally use a huge beltsander type machine to bring them back flat.
Reply:Hello again ncoloqerojr, I was fortunate with this situation, this was a "new" engine that students had broken so it did not have all of the grease/dirt/chemicals that are all too often present. If I were dealing with cleaning the part that you have in this thread I would first either use a pressure washer with soap to clean as much surface contaminants as possible or put it through one of the hot water/chemical parts washers and then afterwards use a bead blaster to clean the immediate area of the repair and then likely use acetone/alcohol to assist with embedded oils/chemicals. Then, I would attempt the weld bead build-up. Good luck and regards, Allanaevald
Reply:I was able to get the job done . It is certainly not the prettiest, but should work out just fine. At least I learned a few things.