hardening

[johnno]

I have a question about selective hardening, selective tempering ect . What in your opinion is better. Is it better to have a soft drawn spine or springy spine I have tried both and there are benefits to both methods but what is YOUR opinion, is clay coating better than drawing with a torch/forge.
I'm not trying to open a can of worms here but I'd like to here what other people think.

[Jerry Hossom]

I'm going to move this to Ed Caffrey's forum where I think you'll find more folks who can answer your questions.

[Tom Ferry]

Hi Johnno,
Well in my opinion how hard or soft the spine is all depends on the knives intended use and function and chance of warpage during the quench. I will fully harden my hunters unless I want to show a hamon or temperline. I normally seletive harden or edge quench my larger knives, not necessarily for aesthitics or for a soft tough back, although this can be a bonus, but more for less risk of warpage during the quench.
For example when I make a rope cutting competition knife I edge quench but do not temper the blade at the temp I would for a camp knife. I more or less stress relieve the blade, meaning the edge is about as hard as you can get away with without chipping under its intended use. If you used the same blade for chopping wood it would possibly break out. That doesnt mean its a bad heat treatment but the knife was heat treated for a specific task because the edge holding will go up a little which in competion can be crucial.
Currently I am mainly using clay and water quench for the 10xx series steels with great results but I still use oil for most of my damascus and either a full quench or an edge quench. I have never had much luck with the soft back draw with a torch personally but some do.
What you said about benefits of both heat treatments is right on and as an individual smith you must employ the technique you feel meets the needs of the overall package of that knife as each knife usually has a specific or intended use.
Have fun!

[johnno]

thanks tom I'm currently trying to make a rope cutting/skining knife. I forged the blade from 5160 triple quenched in 60
degrees C water and tempered to 350 F three times. I want to start making blades that will perform very well and pass a 90 degree bend test thats why I'm asking about harening styles. I have made a couple of D2 blades that met these tasks and passed very well but I want to learn more about different materials.
Thanks again for the help.

[Bob Warner]

Go to Ed Caffery's site. He has step by step instructions on how to make a blade that will pass the journeyman test. Including answers to all of your questions.

[Gene]

Good day, Gentlemen:

I have a long blade, the cutting edge of which I would like to very precisely harden for 2' 1/2", but I was wondering if you have had any particular experience with:

INDUCTION HARDENING, where the sharp edge is placed inside an AC electrical coil, which energizes the steel and heats it up, depending on the frequency and amperage, for an extraordinarily precise edge hardening, or

Similarly, I would appreciate hearing from any of you who have had any experience with LASER BEAM HARDENING. A phosphate coating is applied over the sharp edge to facilitate absorption of the laser energy, and then the edge is quenched and tempered.

Or finally, have any of you tried any experiments with ELECTRON BEAM SELECTIVE EDGE HARDENING: Electron Beam Hardening is similar to laser beam hardening.

Thank you very much.

Gene

[jbgatlin]

Laser beams, eh?

[Gene]

Yes, Sir.

A lot of the kit knives today are laser profiled, and there are companies which do selective hardening on knife blades by laser technology.

And I'm trying to learn more about it.

Thank you anyway.

Gene

[jbgatlin]

And all this time I have been using a torch! I need to get out more.

[Gene]

Alas, JB, this particular blade is not quite that simple.

The blade is 24 3/4" x 2 1/2" x 3/8", 1084, and only 5/8" up from the sharp edge, I have to cut in an inlay channel, the entire length of the blade, and inlay it with twisted copper and brass wire. Thus, although the sharp edge needs to be hard, the blade needs to be soft enough, only 5/8" up, so that I can cut in the channel.

And, being a dumb, novice and old, I don't believe I am skillful enough to handle that.

Thank you, again, anyway.

Gene

[Tim Adlam]

..........0]

[whv]

let us know how it turns ou for you, gene 0]

[Gene]

Good mornin', Wayne, from the Suwannee River!

Truthfully, I'm shootin' in the dark here.

To cut in that bottom inlay channel, only 5/8" from the sharp edge, I'd normally cut out the channel with a graver and chase hammer, but you can't do that if the steel there is hardened.

But it's a fairly wide channel - has to be large enough for two wires, twisted copper and brass - so just maybe it would be large enough for me to GRIND in the channel with a Dremel tool, and I plan to give that a try this morning, on a hardened junk blade.

But thank you for the encouragement, and yes I'll keep you posted.

Gene

[paul harm]

maybe i missed something, BUT- couldn't you cut the channel before the heat treat ? paul

[Gene]

Good morning, Paul -

No, all the experts tell me you CAN'T first cut the inlay channels, then heat treat and temper the blade, and then come back and do the inlay. All the experts agree that the delicate little channels - with their almost microscopic edges - will be unusable after heat treating, because of the scaling, oxidation and such.

But thanks for the thought!

Gene