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Shaft build up

Yes, I agree with you, I prefer a stick weld such as 6012 or 6013 and have done many shafts with stick and machined them afterwards but I also happen to have a flux core welder so the convenience of continuous welding has some appeal. However the wire is high tensile E70. which is another disadvantage. I'm not worried about the quality of the weld just if there is any discernable difference.
Clive
 
First shop i worked for repaired stamping press parts,so the worn or broken crankshafts got welded.Back in the 70's it was stick,and as wire came in we were using NR 311.
Before the machines got to cut on them,they went to a charcoal and coke fire or the large
gas furnace.Then they cut like butter.
jim
 
I tig weld a fair few sharfts up with a 70 grade filler. Cuts with no issue. That said theres no flux inclusion. If you have a little flux inclusion it will turn with carbide ok ish :-(
 
With the fluxcore there will be inclusion if you dont stop and chip also with the hard wire.

To tig there can be no oil or other impurity

I do like to tig ss on where the seals wipe though
 
I prefer the gas shield. not that it matters.

I get my best results from undercutting the worn area on the lathe before welding, it leaves it nice and clean for welding and dont get hard spots where the work hardened areas and the weld mix. Most of the time you cant even see it was welded up, even good enough for seal surfaces.
 
Yes, I agree with you, I prefer a stick weld such as 6012 or 6013 and have done many shafts with stick and machined them afterwards but I also happen to have a flux core welder so the convenience of continuous welding has some appeal. However the wire is high tensile E70. which is another disadvantage. I'm not worried about the quality of the weld just if there is any discernable difference.
Clive

There MAY be a slightly "tougher" to machine deposit that "may" give a HSS tool a workout,but no problem for a carbide tool. Also, in general FCAW has more penetration and admixture of the base metal than say E6013/ stick. I suggest, as with any welding...try a sample piece of same steel stock scrap with FCAW and cut it.
 
Thanks guys for your responses, I have found a spit motor so if I gear it down I will be able to mount the hand piece to do a continuous run. Of course I will try out a bit first. We always used to turn down to a lesser dia. before welding and a rough finish is preferable for bonding too.
Clive
 
There is a young guy on youtube with many videos showing repair of worn bulldozers shafts ect. I've never heard him say type of weld used, but if you leave a comment or question he will respond. He always responds to me quickly. He lives in Latvia in northern Europe so his English is not perfect but definitely understandable.

Here is one of many videos:

First chips on my Horizontal Boring machine - YouTube
 
Thanks for the link, I couldn't find one on making an automatic weld but for practicalitys sake it makes sense to get the shaft turning and sit there with the hand piece, wouldn't take long. And it's not like it's an everyday occurance.
I imagine there would be a special earth clamp that allows rotation.
 
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I personally will not machine a shaft that's been built up with solid wire. I've had some bad experiences with it. I've had a few customers over the years bring in parts that they welded up with a mig gun using solid wire and it made the welds very hard. This has mostly been cast steel parts. Flux cored wire works much better, even better is to stick weld with 7018. That's all I use when building up steel shafts, and I've done many. If the area needing build up has spun there may be some hard spots and it's advisable to undercut the area first them build up. Use a 7018 or flux core wire with gas and you shouldn't have any problems.
 
If the shafts in good clean condition i would personally just weld it. I know im easily going to get enough penetration to melt - infuse with filler any slight work hardening or impurities regardless of stick tig or mig. I would only under cut if its really ugly - corroded. Even then i would only take off enough to clean up, never turning a length down to the minimum wear. Why remove metal you have to rebuild latter? Lot easier to build up one layer 1" long and another on top 2" long to cover uneven wear! Than it is to build up 2" twice. All the more so as shafts get bigger. its a long way around a 3"+ shaft with a stick.

Comments about straighten, ruff turn and then re straighten are spot on. Even with careful preheat and slow post weld cooling it will be a highly internally stressed weld, it will naturally be shrinking and trying to grip the shaft, relive it as much as you can! needless to say don't quench any weld you want not to crack, all the more so if you want to machine it!

As for seal surfaces, i don't like stainless, to soft wears to quick. My customers don't care how long it takes me to turn of or if i go through a insert or 2, they care about what the down times costing them! Far better to go for a high nickel hard facing rod. But don't try that if you want to turn it with Hss! Carbide cuts it fine and in my experience it really will hold up to most lip seals very very well! So long as its turned to a good finish and lightly honed. Remember though the seal rides on the surface, so don't build up a really worn shaft with hard metal and deeper than you need, start of the base layers with something as near to the parent metal as you can get. Once that seals eaten into the shaft less than a 1/16" it will be leaking again!
 
Abom79 (or others),

Better to weld around the shaft (ie shaft turning in a fixture, welding rod/wire stationary)? Or parallel to the shaft?
Curious minds want to know...

Andrew
 
Welding around is easier if you have a rotating fixture, or in the case of a bore a rotary welder (there really nice but make you feal dizzy eventually) By hand lines are the simplest. Either will still need straightening to some degree.
 
Welding around the shaft is a little better for keeping the shaft as straight as possible but there's still a high probability that it will warp slightly. The best way that I have found is to weld in the lathe using a steady rest and live center. After the shaft is welded keep the center tight as it draws in. An example of what I'm talking about is having to weld one of the journals on a rotorshaft. I have had to weld the entire end of shafts up before because of warpage. In these cases i will weld stringer passes since I have to re-center and machine anyways.
 
Thanks for the info guys! I've done both ways before and wasn't sure if one was better than the other or not. (My 20" lathe gets down pretty slow, so I tried welding a shaft that way once...still holding!)

Andrew
 
If you're gonna mig it, even a 20" lathe's slowest speed would be too fast for me! I would spin it by hand
 
KEF791 on YouTube has a great video on shaft build up.

That was a good video. In the end I built up the bearing area and the threaded end with straight passes. Filled in the centre, redrilled the centre and remachined for the bearing to go on and recut new threads for the nut. It was a stub welded in a tube that is the element for a flail mower. The tube had to be straightened but they pull all over the place anyway when the lugs are welded on for the flails. Redrilled the lugs by turning down a length of bright shafting and drilling out the end of a drill and silver soldering them. Able to drill all the length in one go, about 8 foot long. Now carries 10mm bolts which last longer on the flails.
With the element just worked down along the length using a scribing block, when you find a high point heat that part red about 1 inch dia and use the cutting oil to quench and then move on to the next bit. Got it pretty good in the end and the mower ran without the huge vibration that was the problem in the first place.
 
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