shaft repair

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I have an old cement mixer that has a gear reduction box under it and the previous owner welded the chain sprocket to the shaft then did not install it straight. I cut the sprocket off but the sprocket had been spinning on the shaft before it was welded so the shaft is undersized and I gouged it while cutting the sprocket off. Can I just weld it up with build up rod and turn it back down to size? Its not something worth replacing so Im trying to repair it on the cheap otherwise the mixers going to the junkyard . The other option is turn it from 1 7/8 to 1 1/2 and just turn the bad area out of it. it has about 30 horse running through it. thanks for any advice.
Reply:Most of this old equipment isn't made of anything special so can be rebuilt using just plain 6013 or 7014 or E70s-6. Was the sprocket keyed or clamped originally? What amount of wear is there? For just a little wear, brazing may be easier if that will work without interfering with the gear fit/holding. I know you know to just keep the shaft straight while you build it up.What kind (brand, size) of engine drives this? Anything old and neat like a Novo?
Reply:Originally Posted by idacal ...The previous owner welded the chain sprocket to the shaft then did not install it straight.I cut the sprocket off but the sprocket had been spinning on the shaft before it was welded so the shaft is undersized and I gouged it while cutting the sprocket off. Can I just weld it up with build up rod and turn it back down to size?Its not something worth replacing so Im trying to repair it on the cheap otherwise the mixers going to the junkyard.
Reply:there is no engine on it I was setting it up to run off of a  tractor hydraulic system its a 2.5 yard mixer so it will be nice to have it running. The sprocket was held by a key way and two set screws and when it spun they just kept running it. Its probably undersized by 3/32s and then there is the gouges from when I torched it off
Reply:I would weld it up and machine it down on this sort of thing. I have done it many times. If welding legthwise run beads on oposite sides. If you have a means to rotate it while welding do that, it keeps the stresses radial not axial but don't run more then a few beads before letting it cool.-DanOwnerDW Metalworks LLCMiller Trailblazer 302Miller 8RC FeederMiller Passport PlusMiller Dynasty 200 DX W/Coolmate 1Hobart Handler 135Hypertherm PowerMAX 30Smith O/A Torch SetPlus much much more
Reply:Originally Posted by idacal ...I was setting it up to run off of a tractor hydraulic system ...The sprocket was held by a key way and two set screws and when it spun they just kept running it....
Reply:Im converting it to a hydraulic motor and there is only about 2.5 inches of shaft sticking out of the gearbox I was hoping to do away totally with the gear box but it would take 3 jack shafts to get it down to 7 rpm without having huge sprockets and lots of moving parts to keep in order. edit I dont understand hydraulics enough to be sure that the pump and motor would have enough torque to turn the drum without the gear box.I had a 3 horse electric motor turning at 1750 and turning the drum at 1.8 rpm in low gear (high gear is 11 rpm) and it didnt have quite enough torque at 9 ft lbs to turn it with two yards in it. I am looking at a 100 ft lbs hydraulic motor that turns at 1000 rpm Im hoping my math is correct and it works this timeLast edited by idacal; 10-14-2008 at 02:28 PM.
Reply:If you want to do it on the cheap, build up the shaft, trim it till a good fit with a grinder and weld the sprocket back on straight as you can get it.I would take the shaft out of the gear box so you don't cook the seal and bearings when building it up.David Real world weldin.  When I grow up I want to be a tig weldor.
Reply:Originally Posted by David RIf you want to do it on the cheap, build up the shaft, trim it till a good fit with a grinder and weld the sprocket back on straight as you can get it.I would take the shaft out of the gear box so you don't cook the seal and bearings when building it up.David
Reply:I spent most of the day getting the shaft out, had to build a puller the whole works finally got it out a little while ago. I have access to a lathe just its a joke to use, its to small, and chatters to bad. the shaft is 1.945" Im just going to turn it down to 1 3/4" rekey it and call it good. the local machine shop will do it for about 60.00 so I think thats the best route to go. I found a tapor hub and sprocket for 75.00  but the only issue is it a double chain its at a surplus outfit the proper one is 200.00Last edited by idacal; 10-14-2008 at 07:42 PM.
Reply:Originally Posted by idacalIm converting it to a hydraulic motor... ... I am looking at a 100 ft lbs hydraulic motor that turns at 1000 rpm Im hoping my math is correct and it works this time
Reply:Excuse the non-standard abbreviations, I don't know how to type the "cube" symbol.
Reply:Thanks Sandy,I'll 'speriment with that some time.
Reply:denrep thank you, thats the information I have been trying to understand how it works and that made some sense to me. still not a 100% clear, now here is another thing this gear box is a 20:1 reduction it is going to have a 8" sprocket on it, the drum has an 35" on it so I need about 600 rpm if I am running through the reduction box right? or did I screw up again? my excuse for sucking at this is I had brain damage as a child  at least thats what I TELL EVERYONE.edit my pump will do anywere from 12 gpm to 30 gpm its an 90 horse power packLast edited by idacal; 10-15-2008 at 12:43 AM.
Reply:Originally Posted by idacal...gear box is a 20:1 reduction it is going to have a 8" sprocket on it, the drum has an 35" on it...
Reply:this is the motor Im thinking of using but I havent ordered yet, those numbers are what I came out with roughly so I must be figuring somewhat close http://www.surpluscenter.com/item.as...name=hydraulic
Reply:Originally Posted by idacalthis is the motor Im thinking of using but I havent ordered yet, those numbers are what I came out with roughly so I must be figuring somewhat close http://www.surpluscenter.com/item.as...name=hydraulic