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Lord Of Crows
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Discussion Starter · #1 ·
Hi. Question for metal people: I have a knife blade blank with 3/16 inch holes in the tang but I want to expand those holes for 1/4 inch pins... I tried using a x2 cobalt drill bit for stainless steel but it just chewed the bit up... would it make sense to try and temper the blade for a few hours in the oven to try and soften the steel?
 

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Lord Of Crows
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600 Posts
Discussion Starter · #3 ·
A tungsden carbide needle file should do it
If I could precisely file it I would try it but I doubt I could do it... but I just read something online about how you can use a wood dowel in place of a drill bit to locally temper the spot then drill...
 

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Im from Holland, isnt that weird?
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6,001 Posts
If I could precisely file it I would try it but I doubt I could do it... but I just read something online about how you can use a wood dowel in place of a drill bit to locally temper the spot then drill...
So you're heating up the metal with friction, the metal is tempered and then you drill? That's pretty smart :)
 

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ruthiexxxx
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1,005 Posts
If I could precisely file it I would try it but I doubt I could do it... but I just read something online about how you can use a wood dowel in place of a drill bit to locally temper the spot then drill...
That is a VERY interesting idea ! Localised annealing would save ruining the temper of the blade
 

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Premium Member
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6,101 Posts
To "soften" the blade, a micro gas torch might work, too.
- I heated one spot 'til it was glowing bright, then left it
alone to cool slowly.. Re-hardening is not necessary, imho
(unless the full width of the handle part of the blade had
been glowing..) If you want to re-harden the steel again
(again: a softer, less brittle handle is a positive aspect!)
you will have to find out what steel that really is, how hot
it has to be to then be "cooled" in what medium (oil or water)
- And the oil has to have the right temperature!
After the oil "shock", which hardens the steel but makes it
brittle as well, the blade will have to be "tempered" at around
200 degree centigrade to result in this - and at 180 degree
to result in THAT final hardness..
Metallurgy? is complex.. I'd just glow it where I need to drill
and leave it as it is to build that knife.

kind regards,

Be
 

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Premium Member
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6,101 Posts
Here´s some "little known facts" (haha - enough to study a year or two..):

http://www.dew-stahl.com/publikationen/werkstoffdatenblaetter/werkzeugstaehle/

Should help you a little, as long as you know what steel you use,
and with the help of a dictionary..

We did this hardening stuff with Fabi´s blades, that´s why I recall we wanted to temper at 180°,
not at 200° - to get a slightly harder blade.. (Some freak might want to tell you that knives
don´t belong into the dishwasher! - not because of corrosion, but because of the steel being
affected by temps of even "only" 60°C...)

View attachment 24348

"Weichglühen" (here at 680°C) means to let it glow in order to soften it..

Öl is oil, "Härten" is hardening.

"Anlassen" means to temper steel - one can see that the final
hardness is reduced if tempering is done "hotter" - but elasticity
will increase...

I hope I don´t bore you, plus I apologize for supposing a closer
look may be interesting.- resulting in posts with more than four words..


kind regards,

Be
 

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Lord Of Crows
Joined
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600 Posts
Discussion Starter · #8 ·
Here´s some "little known facts" (haha - enough to study a year or two..):

http://www.dew-stahl.com/publikationen/werkstoffdatenblaetter/werkzeugstaehle/

Should help you a little, as long as you know what steel you use,
and with the help of a dictionary..

We did this hardening stuff with Fabi´s blades, that´s why I recall we wanted to temper at 180°,
not at 200° - to get a slightly harder blade.. (Some freak might want to tell you that knives
don´t belong into the dishwasher! - not because of corrosion, but because of the steel being
affected by temps of even "only" 60°C...)

View attachment 24348

"Weichglühen" (here at 680°C) means to let it glow in order to soften it..

Öl is oil, "Härten" is hardening.

"Anlassen" means to temper steel - one can see that the final
hardness is reduced if tempering is done "hotter" - but elasticity
will increase...

I hope I don´t bore you, plus I apologize for supposing a closer
look may be interesting.- resulting in posts with more than four words..


kind regards,

Be
Thanks Be!!!!!!! I'll let you know how it goes... :D
 

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Lord Of Crows
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600 Posts
Discussion Starter · #9 ·
I hit the three tang holes with a micro torch (thanks Be!) and was able to drill successfully... note: I had to do two heat applications on the one of the holes since it did not drill out as easily as the first two... I actually did get some red hot steel with it on one after about 5 minutes of swirling the pencil flame around the opening... it is fascinating watching the flame hit the steel and the surface color changing... I'm pretty sure some annealing went on in the whole blade but I'm OK with it.
 

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Accident-Prone
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1,513 Posts
I'm interested in the dowel-in-drill annealing process, I've tried something similar with nails instead of dowels but I never managed to get anything to come of it. Did you try the dowel process?
 

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Premium Member
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2,201 Posts
Glad it worked. Pretty much what Be said. As a side note, you can buy annealed blades too. Then you just have to harden and temper it. Also, some "cobalt" bits are nothing more than a thin coating on a HSS bit and only good for very thin stainless. Never heard of the wood dowel method. Got a link to a video?
 

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Lord Of Crows
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600 Posts
Discussion Starter · #12 ·
I'm interested in the dowel-in-drill annealing process, I've tried something similar with nails instead of dowels but I never managed to get anything to come of it. Did you try the dowel process?
I don't have a drill press so I did not. I am curious to know if it would work though...
 

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Premium Member
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6,101 Posts
It most likely WILL work..

friction produced heat..:

[ame]http://www.youtube.com/watch?v=5JbnDXw-0pM[/ame]

a pretty powerful method..

and steel is a pretty weird liquid..


kind regards,

Be
 

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Lord Of Crows
Joined
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600 Posts
Discussion Starter · #15 ·
It most likely WILL work..

friction produced heat..:

http://www.youtube.com/watch?v=5JbnDXw-0pM

a pretty powerful method..

and steel is a pretty weird liquid..


kind regards,

Be
I have seen that video before! Actually, I have this weird habit of watching youtube video playlists late at night on forging and welding (muted sound) while I crank heavy metal music in my earphones... until I am nice and relaxed and can go to sleep. :D
 
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