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Basic sequence for forging knife


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I have been trying to read all I can, I think I have the basics down, but have seen some variations in methods. I certainly want turn down detailed responses here, but just looking for confirmation of the right sequence if forging a knife out of a leaf spring.

 

Here's what seems to be the most common from what I have read thus far.

 

1. Forge to shape.

2. Normalize ( 1 - 3 times)

3. Anneal

4. File, sand, partially sharpen / finish

5. Harden (1 - 3 times)

6. Temper (1 - 3 times)

7. Final finish and sharpening

 

Does this look right? Would you ever want to anneal before forging?

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Why do you think you needs to anneal right after normalizing, please read the heat treat information, I will not re type that all again.

 

I'm not asking yout to retype, I have read it. As mentioned, I have read a few sources, and not all follow the same process , which is why I am asking just for basic clarification of the sequence. With it all being new to me, it can get a little confusing.

 

Here is a quote from a mastersmith heat treating article, which is where I got it from.

 

"After I forge a carbon steel blade to shape, the blade is brought to critical (non-magnetic) in the forge, and allowed to air cool. I do this process twice (normalizing). The blade is again brought up to critical and allowed to cool slowly in Vermiculite. Once the blade is fully annealed (softened) it can be ground, filed, etc."

 

You and Rich have posted lots of info, which is great and I have read quite a bit of it. Plan to read more, THANKS!

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looks fine to me.The fire really doesnt care whether the steel is hardened or annealed,once it gets hot it is soft anyway

 

While I am referencing things, this quote was from another article on here, in the knife classes section, which is not the same sequence as I posted above, it says anneal first, before forging.

 

"Let’s say that you have acquired a piece of leaf spring from a car, first clean it up with a wire brush to get most of the gunk and rust off of it. Inspect it for obvious cracks or fatigued areas. Then cut it into manageable chunks with a chop saw or hot cut. Use a gas axe if you must. After the material is in manageable pieces, you should anneal the steel to make it as workable as possible."

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And lastly, and this may be what confused me a little, the Annealing Methods article I read in the knife classes was presented seperately from the heat treating, so I got a little lost in the sequence.

 

"Before we can sand, grind or file our work, we should get it into a soft state. As explained in the heat treating section, there are various internal physical forms that steel can take. I also explained normalizing. In many cases annealing is just a variation of this."

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Eddie,

 

First, I don't see any advantage of annealing before forging. I am willing to be corrected, but I don't see what good it would be.

 

Also, I use a lot of 1084 and 1075 and find that it is plenty soft after normalization for filing and drilling, so I rarely take the time to anneal. Besides, what we back-yard bladesmiths call "annealing" (vermiculite, wood ash, etc.) can be very hit-n-miss depending on the alloy. I say that if a file and drill will cut it after normalizing, just go with it.

 

I have found great merit in 3X normalization.

 

Don

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Eddie, I think that a few of your steps are out of sequence.

 

 

1. Forge to shape.

2. Anneal

3. File, sand, finish to 220 grit

4. Normalize ( 1 - 3 times)

5. Harden (1 - 3 times)

6. Temper (1 - 3 times)

7. Final finish and sharpening

 

I work with sandpaper and files exclusively, so I need my steel to be in it's softest state. I also don't allow my cutting edge to get any thinner than a dime. In my primitive set-up, a nickel thickness is even safer to prevent warping.  Robert

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There's a lot of great reading material on this site.  Not all of it coincides, more than one way to skin a cat(fish) and dependent on the type of steel you're using.

 

Have you read the Richard Hanson Knife Making post? 

 

I'd been struggling with getting holes drilled in an old file which was annealed by heating to non-magnetic and smothering in ashes.  Fortunately I saw somewhere on this site the suggestion to rub chalk on the area before drilling which worked. 

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Well, for some particular steels, you need a little of annealing before forging (i found it useful on d2, d3, ecc if they have been already forged previously, to prevent cracks, those steels are pretty nasty) but for a leaf spring it's useless. After forging you have lits of stresses in the metal structure so you may need a first normalization (SUB critical heat) and air cooling a couple of time, and then, I suggest to bring the knife blank to austenitic temperatur (amagnetic) and turn off the forge leaving the knife inside the coal. In my forge, which is closed on sides and top, the coal keeps being hot for hours and sometimes the day after it is still warm. Work the knife as you like leaving some meat before the heat treating, if you're using a grinder, if you are working with file and sand paper, there's no way after HT to get the eccess of meat from the knife so it should be almost done. A 220 gri finish wi be appreciated by your hands if you are working by hands only. When wirking with grinders I found useful, to prevent warping, to leave 20/30% of the edge thickess to do after ht, on razor up to 60/70% or, on some kind of steels, I grind completely after HT. But I have also ground finished up to 400 grit before HT with good result and jad warps leaving meat to grind after HT so it really is a matter of luck. In any case, the thickness to leave on the ege on a FINISHED knife before SHARPENING it's 1 to 0.8 mm, it depends on the size of the knife. On razors it's 0.1 mm.

When you work your knife, you create more mechanical stresses in the molecular structure so, before quenching, it is better to notmalize at least 3 times. I noticed that normalization gives its best results if it is SUB critical and it helps prevent from warping (it refines the molecular structure too) normalization. I use to quench in oil 3 times. When I get crazy I quench in oil 2 times and then in water the 3rd. Plus, do the HT in a metal square tube so that the the knife doesn't touch the coal, that will prevent your finish to get ruined by the coal touching the hot metal, it can be annoying if you want a good finish. If the tube is closed at one end, you can also introduce wood chips continuosly to help bunr the oxigen to prevent oxidation/decarburation but this part I am not sure it's not only a myth. I tried sometimes and it doesn't look so different but trying is not bad.

If you are working with bearings steel you'll appreciate a good finish before the HT, that metal in nasty on sand paper. I love it. Cuts lake a laser.

Finish your knife. Assemble it. Make the sheath, THEN sharpen. No good to handle a sharpened blade while making the sheath...

That's the way I use, i am sure it's not the only way but it works for me.

Cheers

Fra

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i do not anneal after forging if...like I showed in the knife making classes...If I can cut the blank with a file after it air cools from forging.

i do not like to make a  knife a long project, I have refined my work steps to be efficient. To have to anneal puts that next in line finishing step into the next day.

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There's a lot of great reading material on this site.  Not all of it coincides, more than one way to skin a cat(fish) and dependent on the type of steel you're using.

 

Have you read the Richard Hanson Knife Making post? 

 

I'd been struggling with getting holes drilled in an old file which was annealed by heating to non-magnetic and smothering in ashes.  Fortunately I saw somewhere on this site the suggestion to rub chalk on the area before drilling which worked. 

 

The Richard Hanson post is one the ones I quoted above : ) .

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Quenchcrack is a metallurgist on another site, and about 4 years ago, he talked about annealing on plain carbon, high carbon steel. He suggested normalizing rather than annealing, because with annealing, you retain large carbides in the steel, and he said that "large carbides are undesirable."

 

In the old books on toolsmithing, the authors almost always say to forge, anneal, harden, and temper in that order. However, the old time authors didn't always know about normalizing and how it better prepared the steel for its austenitizing phase prior to quenching for hardening.

 

Annealing will make the steel slightly softer than normalizing. Some current authors may recommend annealing in order to make your abrasives last longer. This would be an economic reason, not a steel property enhancement reason.

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  • 2 weeks later...

Just to add another reference I thought I would share the learnings from a recently purchased book  "The Complete Bladesmith" (which I have found to be a great book BTW).  The basic sequence in it is:

 

1. Forge to shape.

2. Anneal

3. Rough grind.

4. Harden

5. Temper

6. Final finish and sharpening

 

 

I think that the variation in the proceses used to normalize and anneal kind of blurr the line between normilization and annealing. If I allow to air cool, I have normilized, if I allow to slowly cool in a container with insulating vermiculite I have annealed, but what if I do something inbetween. What if I stick the blade in sand and the cooling rate is slower than air but faster than vermiculite? Which have I done?

 

My take away at this point, while there might be a "best" way for a particular steel, there are many perfectly acceptable methods to achieve very similar results. I will of course continue to read and learn and ask questions, but feel that I am now going to just have to put them to practice to see what works for me, and my forge and my materials.

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