Broken Shaft

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I was asked to weld this back together.  Its a post hole digger drive motor shaft.My son and I couldn't drive the piece of shaft out of either end of the coupler, so he sliced it in half with the plasma.  We tried the portaband first, but its hard steel.Here is the shaft the customer took out of the motor.The coupler.  The only thing driving the coupler or the bit(auger)  were bolts.  No hex or square drive.I ground the shaft flat, and cut a bunch of 45* angles on the end of the 7/8" square stock with a grinder.  Tacked in place and straight.After a couple of passesReal world weldin.  When I grow up I want to be a tig weldor.
Reply:Checking straight again while its hot in case I need to adjust it.  It stayed put.Finito!Arcmaster 185 turned all the way up  I used what I needed for amps.  misc colored 3/32 tungsten, 3/32 er70S-6, 15 Cfh Argon, #7 gas lenz.A couple hours total.  I let it cool between passes.But wait, there is more.Real world weldin.  When I grow up I want to be a tig weldor.
Reply:I also got to put it together. Here are the partsand instructionsThis is where those balls went.  The customer said "when I saw those bearings fall out I decided to have you put it together, I have seen you do that before."Its assembled and now uses square drive augers.  Whatajob!Real world weldin.  When I grow up I want to be a tig weldor.
Reply:Nice job....i like your turn table.Millermatic 25230A Spool GunDynasty 350 Trailblazer 302HF251D-1
Reply:Nice work, DavidThose bolts where not shear pins were they? I am wondering I think I might be missing something.Miller bobcat 225d plusLincoln sa200Victor torches Chevy totes it on the flatbed It does not have to easy, just possible.
Reply:Any auger I have seen drives from a spline, hex or square drive.  The bolt is supposed to keep the bit from falling off.  This was a cheesy setup.It belongs to a rental company....DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:Sweeeeet Job....Those are hard to do, having to get it straight and all.  I imagine the positioner came in rather 'handy', eh ?I've rented a few of those crappy post-hole digger things and yeah,.. they Suck !Cheers,/Jman...Miller Diversion 165120 amp Buzz BoxVictor Oxy/Ace Oxy/LPGSmith "Little" Oxy/LPGHypertherm Powermax 30Lot's of Misc. tools n' crap....
Reply:Awesome job as always David.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:Looks good David. weld it like you own it
Reply:David, I've heard two schools of thought on welding shafts.  Full rotational weld, and a bevel two sided weld.  I still don't know which is best.  I do the two sided bevel because I don't have a positioner.Another thing that's been argued is whether the shaft will break in the welded area, or on one side, or the other, of the welded area due to the extreme heat during welding.  I've had it put to me that a shaft doesn't have the ability to dissipate heat from welding like a piece of plate, and the HAZ is where the problem occurs.........not the weld.I got a pretty severe dope slap for the blued area around the weld.  It was a sign of very high heat.I dunno, but it is a good thing for all to discuss.I know this isn't the main propeller shaft on the QE2, but the theory is interesting.Was there any way to do a runout measurement on the shaft after welding?  The coupler will probably take up a few thou anyway.  It's a common coupling on augers.  Those things get beat to a pulp  The bolted assembly is a shear pin to take up the stress, and break, to protect the gearbox."Any day above ground is a good day"http://www.farmersamm.com/
Reply:Originally Posted by farmersammI know this isn't the main propeller shaft on the QE2, but the theory is interesting.
Reply:Farmersamm  I have done this before.  Usually its cut off the square shaft and weld on a new one.Look at the size of the shaft and the size of the new "drive".  The drive will break first.  A few years ago I bought 5' of that 7/8" square stock just for post hole diggers.  I have 4' left and none have broken yet.  The square piece drilled pretty easy, its not hardened.I used to weld them all the way around with out a positioner, its just easier and faster now.  First I refused the job, then the customer had no other way to fix it with out buying a new drive motor, so I said I would give it a shot after he took it apart.David Real world weldin.  When I grow up I want to be a tig weldor.
Reply:Nice fix David R.I like the run-out gauge.  The original design doesn't seem like it has much motor shaft for direct driving an earth auger, does it?I don't know where the 7/8" square habit got started, but that's sure a popular size for drives; much more so than 3/4" or  1" square.Good Luck
Reply:Thanks, David for posting this repair. This is what makes this forum so interesting, seeing how different welders approach a repair. I like your approach and I definitly learned something. Great job.