Turning down weld

This topic has 14 replies, 10 voices, and was last updated 12 October 2014 at 11:59 by IanT.

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1 October 2014 at 20:57 #165256
nigel jones 5
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@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?
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1 October 2014 at 20:57 #7320
nigel jones 5
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@nigeljones5
1 October 2014 at 21:08 #165260
Michael Gilligan
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@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.
1 October 2014 at 21:34 #165266
Neil Wyatt
Moderator
@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
1 October 2014 at 23:38 #165284
nigel jones 5
Participant
@nigeljones5
Neil…what on earth are you on about?? Dogs?? Rabis??
2 October 2014 at 07:25 #165298
JasonB
Moderator
@jasonb
Fizzy have a look at this its JS's thread which shows plenty of welds being turned down.

J
2 October 2014 at 20:44 #165378
nigel jones 5
Participant
@nigeljones5
Ive got it! Im confusing this job with one where I welded cast iron….it was so hard I couldn't turn it!
2 October 2014 at 20:57 #165385
ronan walsh
Participant
@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.
4 October 2014 at 09:19 #165545
John McNamara
Participant
@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
4 October 2014 at 12:29 #165566
WALLACE
Participant
@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.
11 October 2014 at 17:26 #166285
Carl Wilson 4
Participant
@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.
11 October 2014 at 18:08 #166288
nigel jones 5
Participant
@nigeljones5
Job completed – turned down perfect! Thanks
11 October 2014 at 18:18 #166289
IanT
Participant
@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
11 October 2014 at 18:48 #166295
JohnF
Participant
@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
12 October 2014 at 11:59 #166353
IanT
Participant
@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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