first kitchen knife disaster!!!

[kansas stik man]

I forged my first santuko chef knife and it went really well i have been grinding for two days to get where i wanted to be and fired up the forge to quench.  this is where disaster struck.  i quenched the knife and when i pulled it out of the oil it looked like a snake.  i try heating and quenching several more times but the waves just got worse even after straightening them.  i finally made the call that the knife was no longer usable and put it in the vise to see how hard i had gotten it and how easy it would break at full hardness(a little self taught lesson) the blade snapped right off at top of the jaws.  nice clean break.  didnt take but about 10* angle before it snapped.  after inspecting the grain size it seemed to be not super fine and not super coarse but a happy medium.  and looked the same all the way through.  all and all i wish the blade would have turned out but i learned that longer, thin blades are super hard to work with and require alot more delicate touch.  i also think that normalizing should have taken place several times in my process, but didnt and ill do it next time.  if anybody has any more advice for me im more than happy to hear it.  and i still wanna make my santuko chopper so any advice on thin kitchen knives would also be of great appritiation.  

thanks for reading ,
                      J.D.

[gudspelr]

I know guys who make kitchen knives and they end up quenching thicker and grinding the rest of the way hardened.  They had the same problems trying to quench too thin-warpage and/or cracks.  Also, I'm sure normalizing would definitely help out a few things.  Good luck with the next one-it's rarely fun to not succeed with a knife but can definitely learn a lot.

Jeremy

[Auzoutdoor]

I made a chef knife for my nephew a while ago ffrom a piece of Damascus I bought over here from the US and payed a bit for it too as it was about 14 inches long.I ground that blade for a few days getting it super fine and was sick in the guts when I quenched it.I normalised it getting it non magnetic and let it cool between 2 other bits of steel to slow the process down and plunged the blade in light oil tip first straight down when quenching.It came out straight as I was very lucky.I would def not quench unless I normalise first but that is just what has worked for me.
Cheers KIM
 

[Todd Robbins]

A lot of times you can correct warpage that occured in the quench, even if it is severe.  The way I do it is to clamp warped blades between two big worn out files (any two pieces of flat steel that are big enough will work, I just have a couple of worn out files that are big enough), then put them in the tempering oven.  This usually works, but you might have to temper two or three times, or even clamp the blade with a slight bend in the opposite direction of the warp.

edited to add:  I haven't tried it, but I bet you could use a c-clamp to clamp a warped blade to a piece of leaf spring giving it a little flex opposite the warp.

[kbaknife]

What kind of steel? how thick? How wide?
What type of quenchant? How much?
What type of quench tank/motion/etc. i.e. point down in a vertical tank or edge straight down in a large tank?

[kansas stik man]

KARL,  steel was 5160,  blade thickness was about 3/32 to 1/8" , blade was about 2" wide, the quenchant used motor oil( i do not like useing it but i have no quench oil and dont know where to get some) there is 4 qrts of oil in a 15"x 11"x 4" sqaure roasting pan. when i quenched i put in length wise cutting edge down with blade ligned up north and south(did not know if that would matter but tried anyways) i move the blade side to side cuz there is no other space availible.  im not really to upset about it just wanna make it a learning experiance and gather some knowledge for the future.  cooking is one of my favorite things to do and id like to be about to make a full set of chef knives but at this rate ill be a long time. lol thanks for advice fellas.

[gudspelr]

kansas-

It looks like you read through M.S. Cashen's thoughts on the ABS forum about quenching.  One thing I'd highly recommend is not agitating your blade (moving it in the quenchant) from side to side.  Instead, move it through your quenchant from tip to tang.  Sounds like your "quench tank" size makes that a bit difficult, but even if you've got the knife positioned diagonally, could you get a little room that direction?  Either way, from everything I've heard from those who've gone before me, moving it from flat to flat will darn near guarantee (especially with such a thin blade) warpage.

I saw your other post first about what kinds of oils for quenching and responded to that one.  If I were you, I'd look into the engineered quenchants.  If that's more money than you'd like to spend, I'd definitely look into canola oil or vet grade mineral oil.  I remember M.S. Cashen mentioning peanut oil got some popularity because it had a higher smoke (and/or flash) temp than the canola.  Even so, his research showed the peanut oil wasn't quite as effective as canola might be.  There are certainly guys out there that can get some really good results with a few of those mentioned oils and I'm sure you could too.

Also, I'd look at getting a longer quench tank so you can agitate that blade into cooler oil for those long chef's knives.  If you've got a welder or a friend who does, a little scrap steel sheet cleaned up, cut into pieces and welded up makes for a good project.

Good luck and keep trying.


Jeremy

[kbaknife]

Good advice, Jeremy.
Absolutely never move a blade side to side. Read about the vapor barrier.
Also, with 5160, a chromium higher alloy steel, vet grade mineral oil would be much better than any type of motor oil.
Again, read the link I posted.
I can not stress how important it is to try to get a basic understanding of what we are doing inside that piece of steel during ALL of the steps of making a knife.
With just a little grasp of what's going on. many blunders and problems just disappear, and the quality of the knives we make greatly improves.
Google is your friend.
Knife-type forums are your friends.
The ABS is your friend.