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Broken tang

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No skills

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Hi folks!

I've got an old Mawhood gouge from evilbay that needs some attention, the tang has been broken/snapped off of the chisel and I want to weld a new bit on and shape it to form a new tang (then re-handle it) - question is how long should the tang be for a good attachment in the handle?

Thanks for any thoughts...
 

matthewwh

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Couple of inches should be plenty.

If you can clamp it with the blade suspended in water while you weld it you will avoid altering the heat treatment.
 

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Right ok, plan is forming - hopefully will get some 'spare' time at work to fit this in :)

Point taken about the heat, will be prepared.

Thanks chaps.

8)
 

soulboy

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Hi All, as a small aside to this post, can you clarify some terminology so I don't make a fool of myself (again)?
The OP has (correctly?) specified 'broken tang', I understand this to be the metal part which goes into the handle and not the blade/working part, is this right or am I being unduly pedantic? (again) :)
thanks chris
 

Cheshirechappie

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It'll be interesting to see how this goes. I don't want to be negative, but I fear that a good result may be difficult to obtain. Welding high-carbon steel is fraught with pitfalls, except possibly by using a blacksmith's weld, then allowing the finished chisel to cool very slowly before re-hardening and tempering the blade. The problem with other methods is that the welding heat will inevitably cause somewhat unpedictable, and relatively uncontrollable, changes to the heat treatment of the steel. You may end up with a brittle joint. All is not lost if you do, but you'll have to anneal, re-harden and temper as with the blacksmith's weld to get a reliable result, I think.
 

matthewwh

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Hi Chris,

The tang is the bit that ends up inside the handle, followed by the bolster, neck, shoulders and blade.

Sometimes the word tang is also used (possibly incorrectly) to describe an un-handled tool.
 

soulboy

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Thanks Matthew, it is that exact use, on that auction site, that was causing my pedantic head some consternation :)
chris
 

Tinbasher

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Brazing or Silver Solder might be better but I think you are bound to draw the temper out of any hard edged tool. You could polish it and retemper if you kow what it should be.
 

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Its going to be interesting to see what happens, I think the heat will be pretty localised assuming I can get it into a bucket of water quickly - all an experiment really but if you dont try you dont learn...

The offending item is at work ATM so best I can do is link to the ebay listing...

http://www.ebay.co.uk/itm/350582914443? ... 26_rdc%3D1


Which ironicly has better pictures than I can take anyways :lol:
 

No skills

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Just thought it should have some sort of bolster really (thanks Matthew!), not sure how I'm going to achieve that yet - too busy thinking about the tang itself, hmm.
 

No skills

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I know I know... but then I lose the makers stamp :oops: :oops: :oops:

Been hanging round this place too long I think :-" I went to see my parents yesterday and my dad pulled out a carrier bag of wooden jack planes/smoother and said somebody he knows is selling them and am I interested #-o #-o #-o defo been here too long :shock:



:)
 

jimi43

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No skills":32bmva5l said:
I know I know... but then I lose the makers stamp :oops: :oops: :oops:

Been hanging round this place too long I think :-" I went to see my parents yesterday and my dad pulled out a carrier bag of wooden jack planes/smoother and said somebody he knows is selling them and am I interested #-o #-o #-o defo been here too long :shock:



:)
Ah...yes...I see...it is high up isn't it.

Oh well...good luck then! You should be ok if you heatsink the first half at least...stick it in a bag of peas! (frozen of course!)

Jim
 

Cheshirechappie

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Actually, I think Tinbasher and Jimi may have the basis of a solution to this one - silver solder and frozen peas. Here's how.

Make a new tang/bolster piece, with the tang and bolster a close copy of a proper Sheffield gouge. Something like EN8 machinery steel might be better for this than plain mild steel, because it'll be a bit stronger in service - less inclined to bend. Don't use silver steel, or anything that'll harden when heated. On the blade end of the new piece, make it about an inch long after the bolster, and cut a sort of 'bird's mouth' in it, in such a way that it'll embrace the maker's stamp on the blade, but not cut it. That'll also increase the joint area, giving the silver solder a better chance than a plain butt joint would have of lasting. Then carefully grind the remaining tang so that it fits into the 'birds mouth'. Silver solder needs a joint gap of about 0.005" at the most, so a nice fit would be needed. Care, patience and diamond needle files might be in order.

To make the joint, use a low-melt silver solder like Easy-Flo No.2 or Silverflo 55, and Easyflo flux. Clean the joint surfaces THOROUGHLY - absolutely clinically clean, no oxide films or finger marks (a really good rub with wire wool is good for this). Set the two pieces up with careful support to prevent them moving during soldering, and see that they're in line both side-on and front-on. Pack lots of frozen peas around the cutting-edge end of the blade - you don't want this bit to reach tempering temperature, less than 100C for preference. Use a heat source that concentrates the flame on the business area; a welding torch with a soft flame might be best, but failing that, a Sievert torch with a small nozzle. Flux thoroughly, and assemble the bits. Heat up and make the joint, using as little heat as possible. Then allow the whole lot to cool down as slowly as possible - DO NOT QUENCH. You want the tang end of the chisel to anneal, not harden. When it's all cool, trim up the joint with files and emery cloth.

It might be a good plan to do a couple of dummy runs with bits of scrap mild steel to get the bird's mouth about right, and make sure the blade end stays cool during the operation.

Sounds complicated, but it might work, and would give a strong, lasting joint if it did. It would also be far more controllable heat treatment wise than welding.
 

xy mosian

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With a nicely detailed explanation like that, from someone who obviously knows what he is talking about, I think even I could manage the task. Well done Cheshirechappie, and just in case I ever do need to do a job like that Thank You.

xy
 

Pete Maddex

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Hi, Chaps

I bought a very nice 1/8" chisel with a not so good handle, I had a nice boxwood one so I decides to swap it. I clamped the blade in the vice and wiggled and pulled the handle an it cracked by the bolster and broke.
After saying a few colourful words I removed the broken tang filed the bolster flat, it was soft enough to file, and drilled a shallow hole in it, I filled down the blade to fit the hole. Then I clamped the blade in some aluminium soft jaws I have for the vice to act as a heat sink and brazed it together, leaving it to cool slowly.
Its not a chisel I am going to hit with a mallet so it be o/k to use and it seems quite strong.
DSC_0153.jpg


Pete
 

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Cheshirechappie

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xy mosian":3odm8h9e said:
With a nicely detailed explanation like that, from someone who obviously knows what he is talking about, I think even I could manage the task. Well done Cheshirechappie, and just in case I ever do need to do a job like that Thank You.

xy

Thank you, xy - that's very kind of you. Mind you, it was Tinbasher who thought of silver soldering, and Jimi who suggested the method of keeping the blade cool; all I did was 'join the dots' as it where, and Pete has since shown that it's not just a theoretical possibility, but a practical, achievable method of repair.
 

xy mosian

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Cheshire, you have to know which order the dots are to be joined in. Seriously I was thinking particularly of the recommendations for solder, heat source and material. I don't know if the OP is a beginner in this area, but if so then that is exactly the sort of information which would be essential, for non-beginners then this sort of post is a good quality refresher.
Thanks again, xy
 
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