Building up grey cast iron for machining

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I've posted this on a few other forums, so if it's redundant, my apologies.So I came across this Alva Allen 5 ton punch press, set up for shearing angle iron on Craigslist.  Price?  125.00.  Been sitting outside forever and day.  Guy says it needs TLC but is in solid shape.  Get it home (story intself, with stand it weighs about 1200lbs).  Take the flywheel guard off and lo and behold the crankshaft that operates the punch is snapped, the crank journal cap is cracked.  these two items by themselves are not that big of deal because the can still be purchased.  HOWEVER a portion of the main casting was chipped off and is gone forever, the lower portion where the crank cap bolts to.  I go back and talk to the guy and we come to an agreement.  New price, 50 bucks.  The stand it sits on is worth 50 for me so I am happy.  Per the manufacturer this is made of Grey Cast Iron.  Is it feasibly to build this up via stick welding and have it machined?  Am I completely foolish to attempt this?  These presses go for for anywhere from 800 - 1500 in used condition.  Opinions appreciated.
Reply:looks like someone has welded and ground on this before? last pic lower left?
Reply:i think you would be better off doweling and inserting it..tackleexperts.comwww.necessityjigs.comhttps://www.facebook.com/groups/mach...dingequipment/
Reply:I think you're pretty much toast. The portion missing could be studded and brazed but the cost would use up the total value before you bought the crank and cap I think.Then if you did find a small starving shop that would do it, any angularity between the crank bores after machining likely would cause another snapped crank at radius. I would bet that whatever bore is left there is no longer in line so everything would need brazed up, milled and then line bored...Matt(edit) looking again I suppose it could be bored for a thin wall bushing after brazing but I'd prolly not do it.Last edited by Matt_Maguire; 01-08-2011 at 08:36 AM.
Reply:Looks like a pretty straight forward braze repair.  You could almost build it up with braze and bring it back down with a file.  I mean, how precise does this have to be?  We're not talking high rpm, are we?
Reply:Originally Posted by weldbeadlooks like someone has welded and ground on this before? last pic lower left?
Reply:Thanks for the replies guys.This crank is not subjected to high RPM.  One stroke everytime the foot pedal is depressed.  It will experience high pressures on the upper portion of crank journal on the down stroke.  My intial thoughts were to build it up by brazing, file the land where the cap mounted, set the cap in place which would give me the location of the bolt hole.  Drill and tap the bolt hole.  torque the cap in place.  Now there is divergence here on my thoughts of completing this:1.  Take the whole thing to a machine shop have them line bore BOTH journals and insert sleeves.2.  The cap and intact portion of the journal is about 3/4+ of the contact area needed for the crank, with the majority of the pressure on the upper portion of the journal, I could just clean up the surface after filling to allow smooth movement of the crank.  Again it is not high rpm.  Again thanks for all the input.Last edited by jbyrd; 01-08-2011 at 04:02 PM.
Reply:Originally Posted by Oldiron2As I see it, the question is more whether you have the equipment and experience to do it or would need someone else to, and yes, cost then enters into it. What are your capabilities?  Do you know any friends with shops that could do any of the work? Also, if it's scrap without being repaired, what would the experience of trying the repair be worth?  Good advice depends on the answers to these questions.
Reply:I think your biggest concern will be the new threaded area. I'd see if there's enough material to make the new hole deeper and/or larger in diameter to try and get more hold so you are not relying on the patched area too much..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:Originally Posted by jbyrdNo machining equipment, welding equipment I have.  Experience with cast iron? Nil.  I have a fair amount of personal brazing experience.  Not including this website I have a few contacts that can help with knowledge/experience.  At this point I can't break this thing anymore, will attempt the filling myself, and get help with the rest.  I have some grey cast iron that I can practice on.  Thanks!
Reply:Would I attempt it?For a new customer, no.For one of my regular customers, yep but I'd tell them no promises..For myself, Hell Yah!!Never surrender a machine before it's time.I have to agree with Oldiron2 on this:Also, if it's scrap without being repaired, what would the experience of trying the repair be worth?
Reply:If it was mine, I'd braze it then have it line bored. Grind out bolt hole to bottom of bore wide enough so it can be brazed fully. Use cap to locate hole, drill and tap bronze. Most bronze fillers have a higher tensile than cast iron.PeterEquipment:2  old paws2  eyes (that don't look so good)1  bad back
Reply:Originally Posted by castweldIf it was mine, I'd braze it then have it line bored. Grind out bolt hole to bottom of bore wide enough so it can be brazed fully. Use cap to locate hole, drill and tap bronze. Most bronze fillers have a higher tensile than cast iron.Peter
Reply:Originally Posted by castweldIf it was mine, I'd braze it then have it line bored. Grind out bolt hole to bottom of bore wide enough so it can be brazed fully. Use cap to locate hole, drill and tap bronze. Most bronze fillers have a higher tensile than cast iron.Peter
Reply:Originally Posted by 76GMC1500Looks like a pretty straight forward braze repair.  You could almost build it up with braze and bring it back down with a file.  I mean, how precise does this have to be?  We're not talking high rpm, are we?
Reply:It's hard to tell from a photo, but the casting looks like it has been broken for a while . . . and the two pieces have been rubbing on each other.  Are there additional cracks in the casting?  (There are lines parallel to the bore near the crack).   You sould remove any damaged material before welding.  As for the crank, it's a fatigue failure.  You can see the starting point in the high stress area . . . opposite the connecting rod.  If you machine a piece of carbon the size of the crank and clamp it in the casting, you can make your bronze weld and will not have to line bore.  As you stated, the bottom of the bearing is lightly loaded and does not need to be perfect.  Just make sure the crank turns freely after you've finished.I've made the same type of repair on a 15 ton horn press . . . including welding the crank (it shut down production).  Only hand tools were used . . . total time about 6 hours.  The bean counter was too anxious to let me make a drawing of the crank (it was an old machine), but it ran for over a year before the crank broke again.  That was about 3,000,000 cycles.  The second time I made a drawing before making the repair.  JimDynasty 300DXSmith He/Ar gas mixerMM350PHobart Handler 120Smith LW7, MW5, AW1A