file knife

[ausfire]

I have never made a knife except for paper knives and rail spike knives, so I found an old file and forged a sort of a blade. I intend to rivet a wooden handle on later, but I guess it needs some sort of heat treatment first. I forged the blade roughly and let it air cool and then just cleaned it up  - it hasn't been near water or oil so far. Couldn't drill rivet holes in the handle so they are punched. The blade has taken a reasonable edge on the oil stone.

I have got a bit bogged down reading the stuff on heat treatment and am not sure of the next step. I could just leave it as it is and add the handle but I would like to know the right way. I know it's only a KSO (knife shaped object) but hey, you have to start somewhere.

[Latticino]

Old files are typically reasonable to good high carbon tool steel and should be able to be successfully hardened (unless they are medium carbon steel with case hardening, but that is another story).  Would have been a  good plan to chop off a small section first to see if it hardened, but since you are here I'll tell you what I would do.  A bit involved, but this will give you a chance at a final knife rather than a KSO.

Basically I would go through the conventional "safe" heat treatment cycle for unknown tool steels (do read the stickies for details, I'm not going to repeat everything that has been written on this complex subject).  Be careful when heating to not burn off your thin edges as they will heat more quickly.  You will probably have to make a less hot forge environment and move the stock in and out of the fire to heat it evenly:

1. Normalize 2-3 times by bringing the stock up to successively lower temperatures in the cherry red range and below and letting it air cool without resting on any surfaces.
2. Heat to just above nonmagnetic and quickly quench blade section only in preheated canola oil (preheat to around 140 deg. F)
3. Check if hardened with a fine file (skates on surface rather than biting)
4. Wash off all surface oil with steel wool or the like
5. Temper in oven twice at around 400 deg. F for an hour
6. Finish sand surface to remove any new scaling (reducing atmosphere during any heating will help with this)
7. Assemble blade with handle

[Bo T]

You can also do a differential temper, at step 5 above, at the forge. Use a hot piece of metal (or a torch) to heat the spine (carefully) from the spine to the edge. Try to get straw colored along the edge. Don't worry about pushing past blue on the spine.

[ausfire]

Thank you Latticino and Bo T. I like the checklist way of doing things - easier to follow for those of us with little experience. I am enrolled to do a knife-making course down south in July and I just wanted to try a few things first so that I have some idea of what to expect. I have read a lot but I hope to learn first hand how to deal with heat treatment. Thank you for taking the time to answer. Appreciated.

[ausfire]

A moment's inattention ...

 

[Mark Ling]

wow, I'm sorry to hear that. I was looking foreword to seeing the finished piece. Its all right ive done that SEVERAL times. that's one of the downsides to a coal forge, they get so dang hot! (assuming that's what you used).

                                                                                              Littleblacksmith

[ThomasPowers]

propane forges just end to melt the piece into a puddle if they are over hot...

[Rashelle]

It's better then some of my students first knifes. I'd suggest not sharpening it before hardening on the next one. Bring the edge down to not less then a quarters thickness prior to hardening.

If I may make a couple more suggestions ....... Though I'm far from an expert. You can compensate for the recurve of the blade caused by hammering out the edge bevels either by prior curving it the other way or gently straightening the curve out as you go, or both as needed.

The other thing was (and this is just the way I show to do it) when shouldering in a handle transition, I do the handle before the blade. Holding the blade section in tongs, I shoulder on near side edge of anvil, thus gently narrowing the handle to flare out towards the rear. Giving a reverse taper and dividing the material for further forging. OHHHHHHH do I hope that made sense and helped.

[ausfire]

Littleblacksmith: No, I use a side blast forge and only charcoal. I was intending to heat it to just above magnetic as per instructions above, but I was distracted and kept turning the blower without thinking. Should have left it nearer the surface too,  so I could see what was happening.

Rashelle: Thank you for the useful suggestions. I would really like to see firsthand how a knife is made. I have read so much about how it's done, but there's nothing like practical experience. A week from now I am going to a knife-making course so I hope to return with a better knowledge of the process.

[Rashelle]

You're welcome Aus. Good luck and enjoy it, I'm sure you will. Take your time, make each stage. I took a Japanese chef knife class not long ago from Arnon Kartmazov, Nitzan Lilly was there assisting. I've been meaning to put what he told me in the quotes section, he said:

"To put it all in one sentence, What we do is make clean lines."

I try to keep what he told me in mind, no matter what I'm doing. "What we do is make clean lines." Keep it clean as you go and in the end it'll take care of itself.

Enjoy the class.

[T.J.watts]

try putting a piece 2'' pipe in the forge and heat the blade inside the pipe. I use coal and if your not paying attention you can easily destroy all your work. With the pipe you can still see whats going on and get an even heat.