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I Forge Iron

Leafsprings steel


Kenny gibbs

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I recently got some leafsprings steel from my work it's off an industrial frontload garbage truck, I was getting ready to drill holes in my tang for the scales before I quenched my blade and noticed it was already hard, I skated a file right off it, I went and grabbed a blade I forged but had not cleaned up yet and it was also hard, file tested it skated right of long story short I could not drill the blade and had to drift holes  what could have caused this 

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auto quenching or contact quenching would be my guess Hard to tell without more details like: is it high summer or the dead of winter where you are at?

Anyway some alloys will air quench in thin section where they are listed as being oil hardening in the specs---which BTW are based on 1", 2.5cm, thick cross sectional areas. Knives being MUCH thinner---I do so hope; react a bit differently.

Many hardenable alloys will harden when placed hot in a vise or laid on an anvil face due to the heat conduction of the metal on metal---especially in cold weather!

Now you will notice that many of the books on knife forging you will have read strongly suggest annealing a blade before grinding/filing drilling the tang, etc. There is a reason for this! (If you are just making it up as you go along---it's cheating to ask questions about stuff that has already be covered many times!)

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How hot and how slow? Air quench means it will get hot in still air. Many smiths will stick the blade in an insulating material like ash or vimiculite, or leave it in their gas forge and shut it off. 

Further some air quench steels quench at lowere tempechures than they aneil at. Alloys do weird things some times. 

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Kenny: Perhaps you'd save yourself a lot of time, effort and possibly valuable steel if you did a little reading in the knife making section of Iforge. Annealing, normalizing, hardening and tempering are well covered by guys who know what they're talking about, more than one are published authors on the subject.

I'm not trying to brush you off or be harsh. Unfortunately you need to know more than you do to even be able to ask good questions let alone understand our answers. Please believe me I'm not trying to run you off I LOVE seeing pics of the blades folk post here all the time. I'm no a bladesmith guy but I sure appreciate the skills and craft involved. I really want  you to join the ranks of great bladesmiths. It's all a matter of inherent talent, knowledge and practice. That's on you little Brother, we'll help but you have to get the ball rolling. 

Frosty The Lucky.

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38 minutes ago, Kenny gibbs said:

It's still summer time in Kentucky, I did try annealing the blade and to no avail still could not drill the tang. I think you are right about the heat conduction did not think about that, 

Hi Kenny welcome to the forum... If you go to your profile and put in your location you may be surprised how many of the gang (including bladesmith's) are near you and willing to help. In about ten min we will have forgotten this post.:)

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NOTHING to be sorry about Kenny, we ask that of folk all the time. I think you're going to fit right in here. We're about passing the craft along and only get curmudgeonly when folk ask questions then cop attitude about not hearing what they want to hear. 

The spot heating trick might work to get your holes drilled but having read your previous posts I feel you REALLY need to do a proper annealing cycle, there's NO TELLING what state your blade is in right now. It REALLY NEEDS some time to relax, allow the crystal boundaries to break down and the carbides come out of solution. I use garden perlite to anneal in if it's sensitive and a blade is sensitive. It's so thin it might cool too quickly taking it out of the forge and stuffing it into the perlite.

I anneal thin stock with a heat sink. I bring two pieces of relatively heavy stock to the target stock's critical temp. Then I clamp the target stock (Your blade in this case) between the two, wrap it in Kaowool and bury it in perlite. The Kaowool is to prevent air circulation and admitted over kill on my part. By clamp I mean a sacrificial pair of wide jaw vise grips, the cheapo Chinese close out store rip offs work a treat.

The heat sinks will bring the blade to critical temp and NOT above. Typically my anneal box takes over night to cool enough to touch, say 14-18 hrs. My anneal box is the bottom half of a 55gl. drum with a lid and it's full nearly to the brim with garden perlite.

For larger target stock I toss it in the gas forge when I shut it off for the night and I close it up tight with the baffle bricks and plug the holes with kaowool to prevent air circulation. If the target stock is thick, say 3/4" in any three dimensions I put it in before I shut the forge down to soak enough heat the center reaches critical. My gasser typically takes about 8hrs to cool below tempering heat and is a decent anneal. For serious annealing it's the perlite box.

Frosty The Lucky.

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Another great point that has not been mentioned is the type of drill press being used, I know from personal experience sometimes even though I aneal my steel over night in my forge I still can't drill it, my little craftsman drill press will only turn so slow and seems to not like drilling semi hard tool steel, but I can take the same blade to work and use our larger industrial press that turns slower and has more compound pressure, it will go on through. Also a quality drill bit makes a difference as well. 

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If we seem grumpy at times it's because we care; If we didn't care we wouldn't be spending time trying to help---or would have been banned for life + 247 years...

In general we're trying to help people NOT to make the mistakes we did when we started out---many of us in pre-internet days. Lots more fun to make new and improved mistakes! (And a much shorter learning curve too.)

Will you be going to Quad-State this year?  And have you met the local ABANA affiliate yet?

(Re drilling---a cole drill can usually drill through a leafspring fresh from the vehicle with a good bit!)

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As Johnny mentioned quality bits, for example... Cobalt bits are good for the harder side of things. Also drilling a small pilot hole before finishing with your chosen bit can be a massive help. Using coolant or oil to keep the bit cool and taking your time is also worth noting!

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I got mine at the local fleamarket, Friday mornings at an empty lot in a town of 10K people---when the University is in Session.  US$15 with the original paint on it and all the pieces.  Had to pay $20 for the small wilton bullet vise.  I miss that fleamarket; mostly locals rather than dealers.

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