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NB Esk

Frost damage.... Lister Blackstone.

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Thats impressive, is that stick or TIG?  what part does the can of petrol play in this process?  is it just to make you concentrate extra hard :)

 

.................Dave

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7 minutes ago, dmr said:

Thats impressive, is that stick or TIG?  what part does the can of petrol play in this process?  is it just to make you concentrate extra hard :)

 

.................Dave

 

Thanks, forgot to say it's stick 7018 rods (my favourite).  Turned the amps down as low as I dare, that's why the bead is a little crowned.  Other side not so neat, had to lay down a kind of pad, to cover those old stitches.

 

It was cold by the time I was by the petrol can, lol.....

 

 

IMG_0635.JPG

Edited by NB Esk

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Can you explain what is happening in Pic 2 please?  I'm assuming you haven't been photo bombed by a summer BBQ......

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11 minutes ago, GRLMK38 said:

Can you explain what is happening in Pic 2 please?  I'm assuming you haven't been photo bombed by a summer BBQ......

 

Cast iron is a difficult metal to weld and would be even more so if it wasn't pre heated.  The casting was placed back in the fire several times to ensure it remained hot.  The repairs took about six hours but more than half of that was waiting time, while the casting came back to temperature.

On completion the part was left in the fire to try to normalise the casting with the weld metal.  It was still warm to the touch the following day, so had given up it's heat gradually.  In short, if this process wasn't followed, the repair would be likely to crack.  Hope this is of interest.

 

 

 

 

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I’ve got a knackered K2 cylinder with corrosion that bad that pieces are missing. Do you think by using pre-heating and cast electrodes or stainless mig that mild steel repair pieces could be grafted in, or would similar cast material have to be found? 

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37 minutes ago, noddyboater said:

I’ve got a knackered K2 cylinder with corrosion that bad that pieces are missing. Do you think by using pre-heating and cast electrodes or stainless mig that mild steel repair pieces could be grafted in, or would similar cast material have to be found? 

 

It's only my opinion but I do believe small patches/pieces (of a different material) could be welded into cast iron to replace a missing bit.  Okay they're going to try to contract at different rates but that's what welding tries to do and it's why they have to cool over a long period.

 

If it's an important part, as yours sounds to be, I would try to do this on a scrap item (it's something I've never tried to do) to see what happens.

 

 

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I’ll give it a go with the worst of a bad pair, not much to lose on that one. 

I’ve got some bits of large diameter pipe, about 10mm thick, could work nicely if it welds. 

If not it looks like a trip to Glasgow with a van full of used notes! 

  • Greenie 1

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2 hours ago, NB Esk said:

 

Cast iron is a difficult metal to weld and would be even more so if it wasn't pre heated.  The casting was placed back in the fire several times to ensure it remained hot.  The repairs took about six hours but more than half of that was waiting time, while the casting came back to temperature.

On completion the part was left in the fire to try to normalise the casting with the weld metal.  It was still warm to the touch the following day, so had given up it's heat gradually.  In short, if this process wasn't followed, the repair would be likely to crack.  Hope this is of interest.

 

 

 

 

Fascinating, but wouldn't the weld material still expand/contract at a different rate to the cast during normal usage anyway?

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9 minutes ago, tree monkey said:

Fascinating, but wouldn't the weld material still expand/contract at a different rate to the cast during normal usage anyway?

It should be ok the way John has done it.  Not dissimilar to the reason why we used to have ''run in'' vehicle engines gently. Not for just so the bearings and bores run in and mate together better but all the different sized and types of metal used with different rates of expansion and contraction need to be gradually normalize and to equalize them as best as possible by keep running the engine up to normal temp and then cooling right down. An engine ran in better and quicker by doing many short runs, heating up and then cooling right down than doing long continuous runs.

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1 hour ago, tree monkey said:

Fascinating, but wouldn't the weld material still expand/contract at a different rate to the cast during normal usage anyway?

 

That's the battle when trying to weld cast iron.  It's often a fingers crossed moment.  When I initially fitted the parts together I had to tack the pieces together to ensure correct mating.  These tacks (later ground out) were made cold and I could hear the familiar tinkle as the cast started to pull.

As mentioned earlier it had previously been repaired by metal stitching, the only reason for this is no one was willing to try welding it.  Some interesting metal stitching videos on YouTube.

 

 

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4 hours ago, NB Esk said:

 

Cast iron is a difficult metal to weld and would be even more so if it wasn't pre heated.  The casting was placed back in the fire several times to ensure it remained hot.  The repairs took about six hours but more than half of that was waiting time, while the casting came back to temperature.

On completion the part was left in the fire to try to normalise the casting with the weld metal.  It was still warm to the touch the following day, so had given up it's heat gradually.  In short, if this process wasn't followed, the repair would be likely to crack.  Hope this is of interest.

 

 

 

 

Thanks @NB Esk - that makes sense.  I hadn't appreciated the need for pre-heating the whole thing rather than the norm of creating a local hotspot where the weld is taking place.  Every day's a school day....

Edited by GRLMK38
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3 hours ago, noddyboater said:

I’ll give it a go with the worst of a bad pair, not much to lose on that one. 

I’ve got some bits of large diameter pipe, about 10mm thick, could work nicely if it welds. 

If not it looks like a trip to Glasgow with a van full of used notes! 

Have a look at ghe thread on the Kelvin F4 rebuild by tom_ c, and maybe drop him a pm.  He has done some serious weld repair work to cylinders and may well be able to share some experience.

Slinden are also pretty good at welded cast iron repairs, but they will not be free!

⁹9

N

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Short update on the heat exchanger, weld dressed to remove excess material, a coat of sealing paint and it looks to have made a useable service spare.

Thanks for the interest.

 

 

IMG_0643.JPG

IMG_0645.JPG

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There was once a company called "Barimar Ltd" ,who specialized in welding broken cast iron cylinder blocks and heads....some of their repairs were incredible.Most old engine books have a pic of some of the repairs.....one point about using steel weld ,its not got the corrosion resistance of cast iron,so inhibitor must be used in the coolant.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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43 minutes ago, john.k said:

its not got the corrosion resistance of cast iron,so inhibitor must be used in the coolant.

 

True but unable to use inhibitors in this case as the welded area is raw water.  I did "vee " out before welding though, so it has some thickness.

 

 

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On 06/11/2019 at 14:14, BEngo said:

Have a look at ghe thread on the Kelvin F4 rebuild by tom_ c, and maybe drop him a pm.  He has done some serious weld repair work to cylinders and may well be able to share some experience.

Slinden are also pretty good at welded cast iron repairs, but they will not be free!

⁹9

N

The engine that is the subject of that thread is now running in Heyford. HughC

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If it all falls apart I have a heat exchanger of a similar size that could be useful, it won't be a direct fit but I think it would work. I'll post a photo later today.

  • Happy 1

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