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Broken crankshaft? Just get yourself a lathe and stick welder.


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Hello All,

Similar to the cylinder liner video a week or so ago, here is another .

These guys always seem to have a ciggie on and there is always someone in the background, sitting in a chair and doing nothing.

3/4 hour, but an education.

Charlie

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Amazing work.   (Where would he be without a hammer).

The bits joined were from two different cranks I think.  He only removed metal to get them to fit together and you couldn't do that otherwise. At 48 seconds in, you can see where the web has been roughly hacked off the longer part to leave a stub. That means they must have a large selection of identical cranks, broken in different places.

I wonder how long the repaired ones last given that the welded join is only about half of the original diameter - the central spigot being an interference fit only?

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The way we were.

Takes me back to the days of men in brown coats sucking Fishermans friend and with a quarter of Hoburns rough rub in the pocket ready for the pipe. Points to note

Everything this craftsman (because that's what he is) did I recognised, and the easy familiarity in the way he handles his lathe and all the associated tools is remarkable.

Health and Safety...nah he's never heard of it, Spinning lathe chucks and workpiece sharp edges which can cut through tendons and rip fingers off are not figured in his work practices.

The easy use and mix of hand tools (files and emery cloth) with the machining process harks back to early man and still has it's place where fitments of tenths of thousands of an inch can be crafted by art rather than a machine.

He replaces expensive equipment with...skill and touch. Transferring an inside spigot housing bore dia (he's just turned it down and created it) measured by inside calliper... by touch to an outside spigot dia measured by an outside calliper, by touch...that's impressive.

Constant checking and clocking of the important surfaces and bearing diameters, although he's doing this all by hand I'm sure his finished crankshaft will be true. 

Wear,... wow I've never used a lathe where you can traverse the cross slide bed up the bed by hand at speed and let go the lathe feed handle and watch as the bed continues moving by maybe a further 1/4 - 1/2 an inch ! There must be 30 thou slop in the threads, and yet he is still able to achieve high tolerance work using it. 

Welding, well stick welding is very much considered old hat but he is able to weld the machined surfaces to an impressive standard with skilful side wards manipulation of the stick spreading the multiple layers and yet keeping them level and of uniform thickness. When finished and machined there is no sign of porosity or voids in the weld...he's an artisan.

Mick Richards

 

 

 

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1 minute ago, Motorsport Mickey said:

Spinning lathe chucks and workpiece sharp edges which can cut through tendons and rip fingers off are not figured in his work practices.

During my apprenticeship one lad managed to screw his index finger up an internal thread by trying to clean it before the lathe had stopped. (This was in the days before interlocked guards were fitted to machines). He lost the finger - a salutary lesson to the rest of us. 

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19 minutes ago, RobH said:

 

I wonder how long the repaired ones last given that the welded join is only about half of the original diameter - the central spigot being an interference fit only?

The majority of the strength of the weld repair will be on the outside diameter. Getting less and less towards the centre.

I was very impressed by the finished quality of the weld before machining..

 

Roger

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1 minute ago, RogerH said:

The majority of the strength of the weld repair will be on the outside diameter. Getting less and less towards the centre.

I was very impressed by the finished quality of the weld before machining..

Yes obviously that is true but it had broken originally when the metal was full-thickness......... Yes the homogeneity of the welded area was really impressive. As Mick says - a real craftsman. 

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Hi Rob,

although it was a solid section and still broke - the centre was of little use. 

During the breaking process how long did the centre last compared to the outside diameter.

Roger

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Amazing skills, especialy the welding. He must got through a fair number of rods. I wondered if the rods were hardened (I have use some like that to put a hard surface on softer metal) clearly not very hard or the lathe tool would not have coped.  Loved the straightening out jig !  he was pretty slick setting up the 4 jaw

Bob

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Absolutely agree with the above comments on craftsmanship.

That he uses a piece of old cardboard to protect his sandaled toes while welding is pathetic (in the pity sense).

You might enjoy comparing with these videos that use rather different tools, but not contrasting as they display the same craftsmanship.   Made by Kurtis of Cutting Edge Engineering (or rather by Mrs. Kurtis), he's a laconic, dryly humourous Aussie.   A pair of his recent videos  show his good diagnostic skill as well.

First video: https://www.youtube.com/watch?v=bpMD48wb3_s

John

 

Edited by john.r.davies
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4 hours ago, Lebro said:

Amazing skills, especialy the welding. He must got through a fair number of rods. I wondered if the rods were hardened (I have use some like that to put a hard surface on softer metal) clearly not very hard or the lathe tool would not have coped.  Loved the straightening out jig !  he was pretty slick setting up the 4 jaw

Bob

Hi Bob,

 he wouldn't use a hardened welding rod. The original material was not hard in the first place.

Indeed cranks can be case hardene but not with an arc rod.

Roger

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Wow that,s old fashion skills not many could do that today alas. As for welding very good but you should have seen what the coded guys could do with stick welding on some of the oil sites I was involved with! Anyhow that,s recycling at its best. 

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Now if only they made TV programmes showing things like this, I was hooked!

Gareth

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Fred Dibnah would have been impressed with this demonstration of the back street mechanics art at it finest. 

Amazed what necessity brings out in people, sadly I suspect there would be few people now in the UK with more tackle that could undertake a repair. Or am I wrong to think that?

Andy

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Andy,

Have a look at the video I linked to above.   That Aussie's complete business seems to be repairing similar kit for the construction industry.   Not cranks, but hydraulic cylinders and pistons.  He uses much more modern kit, but the same craftsmanship.

John

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On 1/26/2022 at 1:35 PM, john.r.davies said:

Absolutely agree with the above comments on craftsmanship.

That he uses a piece of old cardboard to protect his sandaled toes while welding is pathetic (in the pity sense).

You might enjoy comparing with these videos that use rather different tools, but not contrasting as they display the same craftsmanship.   Made by Kurtis of Cutting Edge Engineering (or rather by Mrs. Kurtis), he's a laconic, dryly humourous Aussie.   A pair of his recent videos  show his good diagnostic skill as well.

First video: https://www.youtube.com/watch?v=bpMD48wb3_s

John

 

Two interesting points came out of the video in the first few minutes.

Back in the 70's a North East DH121 Trident made an emergency landing at LHR as it had a problem controlling its tailplane.

The tailplane is operated by three hydraulic jacks similar to the ones in Johns video. Although the jacks were identical the operating valves had issues.

One of the three valves (one per jack) had rusted ball bearings in its ball race and gave about 1/4" slop in the control valve.

This meant that two jacks were doing one thing and the third doing another.  This caused a panic through the whole Trident fleet.

Eventually one of the jacks pulled out of its mounting in the fin structure (it made a great big hole !!). 

 

The second issue - he did a Dye penetrant test on a steel item - Why!!!  Mag Particle is the correct  choice

 

Roger

 

 

 

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On 1/27/2022 at 10:45 AM, Mike Collins said:

Hi Robh, finger in threaded bore sounds familiar, levelling jack part of apprentices tool kit by any chance?

You've got it Mike.  

( I've still got my jack somewhere but never did find a use for the sine-bar ).

 

 

Edited by RobH
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31 minutes ago, RogerH said:

The second issue - he did a Dye penetrant test on a steel item - Why!!!  Mag Particle is the correct  choice

Roger

Educate us, please, Roger?   Why use one test and not the other?

  I imagine that's what he had available.

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2 minutes ago, Mike Collins said:

We were there at the same time then. Chaps name was Neville if I remember right.

I think you were in the year ahead of me Mike.  It could have been 'Neville '- long time ago now - but the name John Young seems to ring a bell for me.   I've never seen anyone sprint down a workshop like the instructor did though.

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47 minutes ago, stillp said:

The dye penetrant worked though Roger.

Pete

It could quite easily have not.  Dye Pen requires the crack to be very very clean and open to the surface .

Cleaning the gap where the crack faces are is very difficult and needs a repeatable process - often involving HOT chemicals.

Mag Particle on the other hand requires very little cleaning and even the simpler black ink contrast method would show up.

And it can find sub surface cracks.

Preferably for serious detail work one would use Fluorescent Mag particle.

However as the video clip shows Red Dye Pen being used this could easily jeopardise  the use of any Fluorescent method.

Roger

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