Turning down weld

[nigel jones 5Participant @nigeljones5]

I need to repair a wheel with steel weld – mig low carbon steel. I know its a pig to turn , anyone got any solutions?

[nigel jones 5Participant @nigeljones5]

[Michael GilliganParticipant @michaelgilligan61133]

A good mig weld should be no problem to turn … as easy, or easier than the parent metal.

I haven't turned any for a while; but I very recently had some holes in a steel tube mig welded … the welder left them with nice 'mounds' that I filed down to match the tube profie. Absolutely no problem, and the join was barely visible.

MichaelG.

[Neil WyattModerator @neilwyatt]

Sir John of S repairs bearing journals on electric motors that way day in day out. I'm sure I've even seen his dogs doing one.

Neil

[nigel jones 5Participant @nigeljones5]

Neil…what on earth are you on about?? Dogs?? Rabis??

[JasonBModerator @jasonb]

Fizzy have a look at this its JS's thread which shows plenty of welds being turned down.

J

[nigel jones 5Participant @nigeljones5]

Ive got it! Im confusing this job with one where I welded cast iron….it was so hard I couldn't turn it!

[ronan walshParticipant @ronanwalsh98054]

I used to work making and adapting hose and pipe couplings for the pharma and food industries. They were nearly always stainless steel and had to be tig welded and then turned to hide the weld. When done you wouldn't know they were separate pieces, but sometimes the weld metal (316l) would be just noticeable as a slightly different colour. I never had any trouble turning the welds down.

[John McNamaraParticipant @johnmcnamara74883]

Hi Fizzy

Turning a weld inevitably means an interrupted cut, keeping the speed low will reduce the chance of the tool chipping. Also reducing the depth of cut and feed will help. Most of the problems I have had turning welded parts are caused by the rapid cooling of the weld chilling the parent metal and hardening it, particularly if it is a hardenable carbon steel. This problem it is pretty easily detected… there will be a shiny or different colour line between the parent metal and the weld metal

Carbide tooling usually stands up better if you have hard spots. However the shiny areas do have a tendency to stand proud of the work caused by the tougher metal deflecting the tool. These sections will have to be filed or ground down if you need a high tolerance fit.

Regards
John

[WALLACEParticipant @wallace]

Probably a reason why Sir J’s weld turning down looks good is the heavier machinery he probably has don’t complain as much with an interrupted cut !

W.

[Carl Wilson 4Participant @carlwilson4]

I'm sure there are people here who know more, but I have done a little bit of this. Turning down TIG welds…might be worth taking a file over it first, as I had one where the tool dug in at a high spot and the work was literally ripped out of the chuck. Scared the living crap out of me.

[nigel jones 5Participant @nigeljones5]

Job completed – turned down perfect! Thanks

[IanTParticipant @iant]

I've got a B56 type AC motor with a very worn shaft (both ends) and I'm afraid I don't think I'm up to the 'MIG & Turn' solution. I'm thinking about something more within my skill set. On one end (the short one) I think a simple 'sleeve' might work but for the other (longer) one, I am playing with the idea of turning a fairly deep 'trench' and fitting a split sleeve into it. I would epoxy it on – just sufficient to turn it gently down to size. My "theory" is that once in place, the outer bearing surface will hold it all in position (epoxy or not).

I understand the shaft will be weakened but if it works – it's saved a new motor and if it doesn't – I'm no worse off (I hope!). Anyone tried this approach before?

Regards,

IanT

[JohnFParticipant @johnf59703]

Ian, another solution is to "shrink" a sleeve in place, make the sleeve an interference fit on the shaft, I would suggest a wall thickness of about .050" to .060" as a minimum providing of course this does not leave the original shaft too small. After preparing the shaft allow approx 0.002" per inch of dia of the shaft for the interference, heat the sleeve to deep blue and keep the shaft reasonably cool — NO water here !!! this will cool the sleeve to fast, drop the sleeve onto the shaft and have soft hammer handy just incase you need it. there is of course a limit to the length you can do due to the rate of cooling.

I have repaired pots of shafts and altered flat step pulleys to V belt with this method.

John

Edited By JohnF on 11/10/2014 18:49:48

Edited By JohnF on 11/10/2014 18:52:30

[IanTParticipant @iant]

Thanks John,

I will try that at the short end – but I think I'll try another approach at the longer (and 'keyed'  ) end. I've got a few other things to do before I get around to this but I will update this thread on what I actually did (and how successful it was) when I do get around to it.

Got to be worth a try, the motor is a write-off otherwise and a new B56 type 'replacement' will be about £130 (ish).

Regards,

IanT

Edited By IanT on 12/10/2014 11:59:43

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