Straightening fork tines

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Stephen
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Straightening fork tines

Postby Stephen » Sun Sep 22, 2019 11:19 pm

Once they are bent, can I use a blowtorch to enable me to bend them back or will it not be hot enough?
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Re: Straightening fork tines

Postby peter » Mon Sep 23, 2019 1:43 pm

Heat may make the steel more bendable on a permanent basis unless you do the appropriate cooling techniques to make it springier.
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Re: Straightening fork tines

Postby Geoff » Mon Sep 23, 2019 4:53 pm

I agree with that. I had somebody weld a broken tine for me once, the weld held but the tine bent. Research the tempering before you try anything, it might just be a quick quench but I'm not sure. Cold straightening is no use, they just bend again.
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Re: Straightening fork tines

Postby Geoff » Mon Sep 23, 2019 6:23 pm

What a nightmare when you try and research tempering! Here's one I found:

The process of tempering is to remove some of the hardness, hence the term 'temper'.

To do this successfully, and assuming it is a good quality fork, (i.e.one manufactured from medium to high carbon steel), you would have first to normalise the whole fork by heating it to cherry red and allowing it to cool.(don't forget to remove the wooden handle. The steel will now be in it's annealed (soft) state and you will be able to straighten the prong with relative ease.

You would then need to heat it to cherry red and quench it in water. This will make it very hard indeed, but will also make it very brittle. Any attempt to remove a root with this will result in prongs breaking off.

You would then need to temper it by first cleaning it with emery cloth until it is shiny. (if you don't do this you will not be able to see the tempering colours).

You would then need to heat it uniformly; you should notice the shiny steel starting to change colour to light straw, through brown, then various shades of blue to purple. When the correct colour is reached for the degree of temper you require, the fork should then be quenched again. It will now be ready for use.

I am guessing that the colour at which you would need to quench would be dark brown, but you could check this by referring to a good metalworking reference book. A wood chisel which needs very little hardness removed would be tempered to pale straw, while a spring would be blue.

Too much trouble? You're damn right, but I just thought you might be interested to know just how much trouble.
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Stephen
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Re: Straightening fork tines

Postby Stephen » Mon Sep 23, 2019 8:31 pm

OK.
Yes, too much trouble. I'll show you why the tines have bent.
IMG_20190923_110350.jpg
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Re: Straightening fork tines

Postby robo » Mon Sep 23, 2019 10:29 pm

When I was an apprentice joiner I was taught never to let a chisel go blue when grinding them as it would soften the metal I presume it's the same when heating forks ,which wilkies have on offer for £12 at present
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Re: Straightening fork tines

Postby Stephen » Mon Sep 23, 2019 11:16 pm

I'm just naturally in favour of repairing and mending, rather than disposing. (I suspect most of us here are like this)
Fortunately other forks are about, so one or two may have to go the recycling.
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