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Biddlesby
10-03-07, 03:54 PM
Am going to rehandle my frosts mora - plastic handle started to wobble. I would like to put a pin through it, so need to drill a little hole through the tang. Read on a tutorial about locally annealing the metal. Three questions (1) to what colour do I heat the tang (will just a gas cooker hob be ok?) and (2) do I allow the tang to cool slowly, cool it quickly, or drill the hole while it is still hot (how hot) (3) will a normal metal drill bit be ok.

Cheers!

Good thing is if I mess it up - it's only a mora.

narsil
10-03-07, 04:18 PM
You can locally anneal for drilling by putting a blunt metal rod or a scrap drill in your drill and attempting to drill the hole. It wont actually make a hole of course but the heat generated should be enough to locally soften the tang.

If you decide to do it on a hob you will need to protect the blade from the heat. You can do this by either wrapping it with a wet cloth or sticking the blade into a cucumber and keep an eye on the progress of the oxide colouration and don't let it reach the blade. Allow to cool in air. A dark blue colour should be ok.

The best bet is a cobalt HSS drill, but you might get away with a standard drill if you're careful, go slowly and use oil or WD40 as a cutting fluid, be carfeul not to overheat the drill.

PS_Bond
10-03-07, 04:23 PM
You can go through it with a masonry bit & some steady pressure (or use a cobalt bit); an alternative would be to anneal just the area you want to drill. Use a drill bit shank ground to a bullet shape, then run it fast in the press & in contact with the area you want to anneal. It's somewhere on Bob Engnath's site, I just can't find where at the moment.

If you're determined to anneal the thing by flame, I'd take it up to a nice orange glow, then touch it with a magnet to see that it doesn't stick, then stuff the tang into some vermiculite to cool. Sticking the blade in a cucumber (or very large potato), or even wrapping it with wet paper towels should give enough protection to prevent the blade being annealed too...

G.Lamontagne
20-03-07, 03:53 PM
i think what i would do is put the blade in water and fire up a O/A torch with a #1 tip on it (really small) and hold the flame fairly close to heat a smaller area and let it air cool....thats what i would do but im a rookie....im sure there are better ways

CPLPUD
20-03-07, 04:00 PM
You can do this by either wrapping it with a wet cloth or sticking the blade into a cucumber and keep an eye on the progress of the oxide colouration and don't let it reach the blade.

:D Such innovation, I just had to smile when I read this. :D

Inspector71
20-03-07, 04:10 PM
Tried an interesting (but failed) approch to this at Owen's Hammerin.

I inadvertantly hardened my tang and wanted a quick fix. One suggestion was to put a single spot of weld where you wanted to drill, then file it off once cool and aim for the 'hot spot'. It didn't work - even though a nice range of colours radiated out from the spot...

Should have worked well in theory. Wonder why it doesn't :S

Will do it properly with a torch in future. Or just not harden the bleedin' tang in the first place :lol:

Cheers,
Rod

Knife-Man
20-03-07, 04:14 PM
remember that O1 and I wouldnt be surprised if some other steels as well have a horrible tendency despite being oil hardening to air harden right when you don't want them to .. Ive had O1 harden when Ive been grinding it before .. usually eats at least one file before you notice its not cutting :mad: .

CPShines
20-03-07, 04:19 PM
remember that O1 and I wouldnt be surprised if some other steels as well have a horrible tendency despite being oil hardening to air harden right when you don't want them to .. Ive had O1 harden when Ive been grinding it before .. usually eats at least one file before you notice its not cutting :mad: .I messed up a brand new HSS tap that way the other week.

G.Lamontagne
22-03-07, 08:45 PM
Tried an interesting (but failed) approch to this at Owen's Hammerin.

I inadvertantly hardened my tang and wanted a quick fix. One suggestion was to put a single spot of weld where you wanted to drill, then file it off once cool and aim for the 'hot spot'. It didn't work - even though a nice range of colours radiated out from the spot...

Should have worked well in theory. Wonder why it doesn't :S

Will do it properly with a torch in future. Or just not harden the bleedin' tang in the first place :lol:

Cheers,
Rod

mmm it depends on the wire or rod you used while welding...some rods are machine better than others (softer) ect ect...alot depends on what your filler was...machining a piece that has been welding usualy is a bit harder on bits ect though

MushiSushi
22-03-07, 08:54 PM
Sticking the blade in a cucumber

:D :D :D :D

Longstrider
22-03-07, 11:23 PM
I did a lot of work on air rifles in my youth, and whilst brazing a piston head back onto the piston rod I couldn't afford for the heat to reach the sear and soften it. I can remember my metalwork teacher (yes, they let me play with bits of air rifle at school! :) ) sending me out to the local greengrocer to "Buy the biggest baking spud they've got, to stick the sear end in so it stays cool". Worked a treat and that rifle is still going strong.

G.Lamontagne
23-03-07, 07:47 AM
yup iv heard that with knives too....some people stick just the edge in and then temper the blade...the back get soft and leaves the edge hard...things sure are different back home in NA, in finland i made a knife at school (and i carried it in my bag almost every day while making it)...it canada i would be expelled for that

Biddlesby
25-05-07, 11:22 AM
Well I've tried annealing the thing with a flame a few times, got it to blue and tried beyond. Used cutting oil and a rectifer to slow the drill down. At least now I have made a small dimple..before the drill bit broke. I think I need a better drill bit, or I was thinking of getting some professional help. I can appreciate now how hard hardened steel is!

CPShines
25-05-07, 11:30 AM
Well I've tried annealing the thing with a flame a few times, got it to blue and tried beyond. Used cutting oil and a rectifer to slow the drill down. At least now I have made a small dimple..before the drill bit broke. I think I need a better drill bit, or I was thinking of getting some professional help. I can appreciate now how hard hardened steel is!If I'm reading you right, you've heated the tang up to blue and a bit beyond. That's not hot enough to anneal it. You've tempered it a bit, hence it's a little bit softer than it was.

You need to heat the area of the tang well into red hot range. The bit about the colours is that you don't want the blue colour to go down the tang and onto the blade. You can have the end of the tang orange, and the colours will travel down the tang towards the blade as the rest of the tang heats up. Keeping an eye on these colours and stopping the blue from reaching the blade (which would indicate the blade has gotten too hot), whilst getting the far end of the tang red/orange, is the aim. The best way to do this is to be actively cooling the balde whilst heating the tang, hence the cucumber and potato comments :)

Unfortunately even if you do all this correctly, O1's air-hardening ability means that the tang may harden a bit as it cools down and leave it too hard to drill. It's worth a go though.

shing
25-05-07, 11:42 AM
Instead of drilling, how about grinding some notches into the tang with the edge of a grinder, angle grinder or old file for the glue to grip on or you can silver solder an extra piece of metal with a hole in it or a threaded rod to the end of the tang.