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Boyd C-F




Location: Nelson, New Zealand
Joined: 08 Oct 2008

Posts: 57

PostPosted: Sun 26 Jul, 2009 11:47 pm    Post subject: Arrgh - Advice please!         Reply with quote

HI all

I have a bit of a problem that I could use some help on.

I have been reconditioning older high carbon steel knives that I find in junk shoppes and through 2nd hand dealers.

Usually I just re-handle the knives using the existing rivet holes, but I have decided to be adventurous and reshape the knives into mediaeval inspired designs.

I was planning to make a matching handle set of mediaeval kitchen knives, so I need to match the rivet holes. However my standard steel drills wouldn't cut it so I purchased a new 5% Cobalt Steel drill specifically (so it claimed) to cut both high tensile and stainless.
Just over an hour ago I watched the drill get munted by the steel in the knife handle.

Was this just a s**t drill bit or should I be looking at an other kind of drill?

Any suggestions would be great!

Cheers

Boyd
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Peter Lyon
Industry Professional



Location: New Zealand
Joined: 20 Nov 2006
Reading list: 39 books

Posts: 229

PostPosted: Mon 27 Jul, 2009 2:01 am    Post subject:         Reply with quote

I have drilled through heat treated steel with a cobalt drill, they are well capable of it if anything is. The trick is to drill at low rpm's and use cutting fluid so there is minimal heat build up, use a drill press not a hand held drill, and take your time.
Still hammering away
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Boyd C-F




Location: Nelson, New Zealand
Joined: 08 Oct 2008

Posts: 57

PostPosted: Mon 27 Jul, 2009 2:26 am    Post subject:         Reply with quote

Thanks Peter

How's everything up in Welly? Have they got you busy with The Hobbit? Or are you on to something else already?

Cheers

Boyd
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Jean Thibodeau




Location: Montreal,Quebec,Canada
Joined: 15 Mar 2004
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PostPosted: Mon 27 Jul, 2009 3:30 am    Post subject:         Reply with quote

Sounds like those old knives have very good steel so at least the work done on them should be worth the effort.

I would be sure to check if some of these old knives might have " collector's or historical " value before reworking them or if they are already damages enough that it doesn't really matter ?

Some might be worth restoring to their original look but some could become worthwhile medieval type knives with the right hilt furniture and some minor re-profiling of the blade geometry. ( Being careful to not ruin the heat treat unless you plan or are capable of re-doing a heat treat on them ? If grinding just don't heat the blades beyond the point where you can hold them with bare hands ..... i.e. cool the blades often and make only light pressure fast/short duration passes with any grinder.
Belt grinders being the best to use as bench grinders using stones " tend " to vibrate too much in my opinion. Hand held dremel or angle grinders can work if one has a very steady hand and the work is held in a secure vice. This may all be stuff you already know or you may know more than I do and I could be wrong about some details, but I hope this is helpful. Big Grin Cool ).

You can easily give up your freedom. You have to fight hard to get it back!
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Boyd C-F




Location: Nelson, New Zealand
Joined: 08 Oct 2008

Posts: 57

PostPosted: Mon 27 Jul, 2009 3:44 am    Post subject:         Reply with quote

Thanks Jean

I usually go for old butchers/ kitchen knives to rework for what I'm doing - they're cheap, plentiful and it doesn't matter so much if I screw up.

Other than drilling and using a dremel with cutting wheel everything else is done by hand. It takes a lot of emery tape to polish steel...

One day I may look at redoing more sturdy blades - but they are reasonably hard to find over here. Many of our custom knife makers in NZ use old circ. saws from saw mills.

Another chap I know suggested annealing the tangs to make them softer to drill but I don't want to ruin the existing temper.

Anyhow - I'll have to buy more drill bits, luckily it's pay day on Wednesday!

Cheers

Boyd
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Jean Thibodeau




Location: Montreal,Quebec,Canada
Joined: 15 Mar 2004
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Spotlight topics: 5
Posts: 8,170

PostPosted: Mon 27 Jul, 2009 3:53 am    Post subject:         Reply with quote

Boyd C-F wrote:

Anyhow - I'll have to buy more drill bits, luckily it's pay day on Wednesday!

Cheers

Boyd


As I read recently even the best drill bits will fail or wear out very fast if used at high speeds, the way to go is with some pressure ( don't know how much ? ) and slow speeds with a drill press and the bits that burn out/get dull almost immediately at high speed last a long time at slow speeds.

Special lubricating cutting oils or grease may also be something to look into.

If the knives have very good heat treats I would also be reluctant to soften the tangs as going too soft might make the tang very " bendy " at the tang/blade shoulders.

You can easily give up your freedom. You have to fight hard to get it back!
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Maurizio D'Angelo




Location: Italy
Joined: 09 Feb 2009
Likes: 3 pages
Reading list: 3 books

Posts: 649

PostPosted: Mon 27 Jul, 2009 4:36 am    Post subject: Re: Arrgh - Advice please!         Reply with quote

Boyd C-F wrote:
HI all

I have a bit of a problem that I could use some help on.
I was planning to make a matching handle set of mediaeval kitchen knives, so I need to match the rivet holes. However my standard steel drills wouldn't cut it so I purchased a new 5% Cobalt Steel drill specifically (so it claimed) to cut both high tensile and stainless.
Just over an hour ago I watched the drill get munted by the steel in the knife handle.

Was this just a s**t drill bit or should I be looking at an other kind of drill?

Any suggestions would be great!

Cheers

Boyd


If I have understood and translated well.
maybe the steel is tempered. The points with 5% of cobalt is not hard. Need a tip from normal cement, the tip is widia. (Translation from German: as diamond)
Are the tips that are used for wall tiles. is easy and cheap. Wink

Maurizio
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Sean Flynt
myArmoury Team


myArmoury Team

Location: Birmingham, Alabama
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PostPosted: Mon 27 Jul, 2009 7:58 am    Post subject:         Reply with quote

LOTS of pressure and very low rpms. Do that and you probably won't need oil. It's also helpful to drill a pilot hole with a smaller diameter bit.
-Sean

"Everywhere I have searched for peace and nowhere found it, except in a corner with a book"- Thomas a Kempis (d. 1471)
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Michael Pikula
Industry Professional



Location: Madison, WI
Joined: 07 Jun 2008

Posts: 411

PostPosted: Mon 27 Jul, 2009 8:14 am    Post subject:         Reply with quote

You should look into getting a Carbide drill bit. Cobalt is good for un-hardened steels, Carbide just doesn't care and drills the hole. With carbide you will have to use a drill press, either no coolant or lots of it (carbide doesn't like temp changes) and clamp your work. I have drilled hardened L6 with carbide, it works but can carry a $15 price tag. I get mine from www.knifeandgun.com, the website isn't showing the drill bits for some reason, if you have a size you are looking for send me a PM and I can shoot you a part number or just give them a call.

Another thing, dish out the $ for a better quality carbide bit, the carbide tipped ones are not worth the money, a good carbide bit should last a very long time.
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Hanns Wiechman




Location: Minneapolis, MN
Joined: 17 Jun 2007

Posts: 21

PostPosted: Mon 27 Jul, 2009 8:23 am    Post subject:         Reply with quote

I second Michael's comments about carbide tipped drills. Since they're a ceramic they'll cut the old steel with no problems but you want to make sure that everything is held very tight as tungsten carbide will chip if shock forces are applied to it. The other solution would be to use a small grinding bit in a Dremel and use it to drill the new hole through. I've used Dremel chainsaw sharpening bits to grind out hardened steel taps that broke in holes before, if they'll manage that any knife steel will pose no problems. Good luck with the endeavor, post some pics of your creations.
Hanns
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Ben Potter
Industry Professional



Location: Altadena, CA
Joined: 29 Sep 2008

Posts: 342

PostPosted: Mon 27 Jul, 2009 9:45 am    Post subject:         Reply with quote

Third one for Michael's post, more expensive but well worth it, use oil or other lubricant and you should be fine. HARD and low RPMs is the way to go. AND be careful about pegging (bringing the drill out and in during a cut to clear chips, like pounding a tent peg) if you build op too much friction heat (>1450F) and bring the bit out the cold steel around the hole will "quench" the small hot part.
Ben Potter Bladesmith

It's not that I would trade my lot
For any other man's,
Nor that I will be ashamed
Of my work torn hands-

For I have chosen the path I tread
Knowing it would be steep,
And I will take the joys thereof
And the consequences reap.
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Maurizio D'Angelo




Location: Italy
Joined: 09 Feb 2009
Likes: 3 pages
Reading list: 3 books

Posts: 649

PostPosted: Mon 27 Jul, 2009 11:14 am    Post subject:         Reply with quote

This cuts up to 60 HRC. Cheap. The tip is carbide. Here in Italy 4 euro, in U.S. maybe $ 6. Use an ordinary drill, fix the part.
Uffa.



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Boyd C-F




Location: Nelson, New Zealand
Joined: 08 Oct 2008

Posts: 57

PostPosted: Mon 27 Jul, 2009 1:27 pm    Post subject:         Reply with quote

Thank you one and all.

I have a date with the workshop tonight!

Cheers

Boyd
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