Shaft repair ideas

[Spark plug]

Right I’ve chucked it up on the machined surface in the centre, and clocked it on the journal behind the flange, to within 0.01mm. Then measured the runout at the journal at the very end and it’s 0.97mm

So looks like it’s already warped :

But going to have to think about it for the rest of the day, evil back shift

 

[daedalusminos]

I'd indicate the flange and determine what's bent.

 

[Kram]

So looks like it’s already warped

You need two references to clock something in. With just one, it will have whip, where it is only concentric at the point where clocked, with opposing high and lows at either end. To adjust the second point it needs to be tapped.

Depending on the chuck and how its held, whip can return if it decides to chatter. Great fun! I was doing this yesterday..

 

[My Old Landy]

Looks, to me, like the shaft is chucked on the rough part of the shaft. That would introduce errors.

I think he has it on a journal if you zoom in:

 

[brightspark]

a tap on the end with a copper hammer probably will correct it .stuck that far out its not much off center .then u can center drill it for machining

 

[8ob]

I have welded/reclaimed a few cast steel shafts, I dont know what happens to the weld but have found in some cases it can be really hard to turn in a lathe, it can end up glass hard for some reason

Bob

 

[brightspark]

I have welded/reclaimed a few cast steel shafts, I dont know what happens to the weld but have found in some cases it can be really hard to turn in a lathe, it can end up glass hard for some reason

Bob

yea carbon steel and cools down too quick and hardens

 

[Brad93]

Press
On sleeve or spray weld

 

[Seadog]

You need to clock it at the chuck, so you need to have some of the journal protruding, then clock it on the next bearing surface.

 

[Brad93]

You need to hold it on the journal then clock the journal and the free end in. Or you turn between centres.

I've done a few of these with TIG. They always warp.
Personally I'd sleeve or spray weld. PM me of you want it spray welded and you're not in a rush.

 

[8ob]

Right I’ve chucked it up on the machined surface in the centre, and clocked it on the journal behind the flange, to within 0.01mm. Then measured the runout at the journal at the very end and it’s 0.97mm

So looks like it’s already warped :

I would turn the jaws around on that 4 jaw and mount the flange in it , get the stub running true and centre drill it. Then remount with the shaft in the chuck and the stub/flange end in the revolving centre. Soon see what`s going on then.

Bob

 

[Spark plug]

Thanks for the input chaps I shall have anothe go in the morning before work and see ware I get

 

[Laurie Tedcastle]

For anyone that is not familiar with the late John Stevenson's techniques for shaft repair, I would suggest a browse here

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www.model-engineer.co.uk

Laurie

 

[Spark plug]

Ok round two, I’ve chucked the shaft, ware the drive gear mounts, clocked on the bearing journal just in front of the Chuck. Then set the steady and knocked it true with a clock on the same bearing journal as the steady and a clock on the journal right at the end of the shaft:

I’ve got the runout at the very end of the shaft down to under 0.002”, which is a slight improvement upon yesterday’s attempt

 

[daedalusminos]

What's the runout on the mounting flange?

 

[Spark plug]

There’s a little rust putting amplifying the error but the runout is measuring around 0.004” axially and radially.

 

[addjunkie]

There’s a little rust putting amplifying the error but the runout is measuring around 0.004” axially and radially.

Its a mower, not a race care engine. .002 is good.

Id suggest taking it out again. Bore out your sleeve. Then put shaft back in turn to be an interference fit with your sleeve. Shaft in the freezer, sleeve in the oven, and press together. Then machine as one.

 

[daedalusminos]

Id suggest taking it out again

I'd get a centre in it first then clean up the journal so you know rougly what size to make the sleeve.

 

[Munkul]

Spray or sleeve as Brad suggests, but if it was me, I'd see if i could TIG braze it. It will still warp a little unless you do opposing weld runs, but I've had great success with a few built up shafts that way.
If its cast iron then TIG brazing won't work, but sleeving or spraying will.