the hero breaks his blade (warping when dif/hardening)

Knifemaker87

Knifemaker87

Joined
Jan 2, 2006
Messages
1,073
well......
i forged out this bar of 7/8" W2 from "Sunfishman" and made this beatuful tanto blade... big... straight and strong... or so i though.
i clayed to hoping to get a nice choji hammon on it.. (and for i know i did) but it bent the blade to the left slightly... so i normalized it and went back and did it again... i let it soak a little longer int he forge this time. and it bent again!... so i tried to straighten it (becasue of the soft back) but it was too much torque on the edge and i took a chunk out of the hamon
Photo66.jpg

major badness... as it had taken a week of work (i work and go to school) to get it finished...
anyway... my question is would having the blade on the left side of the forge (of of the flame) would that heat one side hotter and therefore make it bend? or was it just... something else? how can i avoid this in the future?
thanks a bunch!
~Chris
 
Anything you do different from one side to another can cause warping ! If you want to straighten the blade do it at 400 F or higher .
 
well... know that one for next time... 400... will do

sigh... well i shall keep it even next time

i was planning on making type of nakiri knife with the rest of the blade as it does have a good hammon on it and doenst require any other real shaping (therefore not having to reharden)

opinions?

thanks
~chris
 
What Mete said. Try a forge like Don Fogg's where the blade is not in direct contact with the flame. Barring that, try using a pipe, capped on the far end, in your forge when heat treating--it will help even out the heat.

John
 
Man, that's a bummer and part of the learning curve. I get little to no warpage because like mete said I do the same to each side of the blade through out the whole process. Like John said also, Don Fogg style forge is tops for heat treating, very even heat on the blade from underneath and the point can stick out the back door. When I have to, I staighten blades right out of the quench, you have a few minutes to do so and at this time the blade is very easy to bend but be careful not to over bend, I wipe the oil off with a rag and holding with welding gloves, I bend straight with my hands and sometimes over my knee. I rarely have to do this but used to a lot years ago. Also over heating the blade can cause warpage. Practice, practice, practice :)
 
i have a little squareish forge...
what is this Fogg forge? i have heard of it before but i dont know what it is. plans? pictures? if i can get pictures i can make one... (i think)

also... i am quenching in water... would that make it warp?

so you take the clay off and then see if it is straight? while it is still rather hot? hmmm.. i will have to get some welding gloves...

any thoughts on useing the remant of the blade? is that gonna be okay?

thanks
~Chris
 
Tough luck Chris, good advise above. What's the pattern in the blade? Almose looks like a "W" pattern. May just be crude and scale, hard to see in the photo.
Ok, so Mete you indicate to try and take the curve out of a blade at over 400 degrees, and Don, you say to do this after the quench. Usually when I've taken any blades out of my heated Brownells super quench, it's at maybe about 150 degrees or less. So would I then heat it back up to the over 400 mark before attempting a bend? Maybe I'm trying to complicate things.
 
Robert, we're talking about two different ways to do this. I quench in a fast oil for about 8-10 seconds, pull out and scrape clay off with a putty knife, sight down blade to check for straightness and straighten by hand all while the blade is hot. You have only a few minutes to do this. I find it nearly impossible to straighten after temper, unless I have a lot of unharden steel in the spine. I have done it in the past but have also broken or cracked blades. With a water quench, I would think you have to straighten after only a 3-4 second quench then back into the water, work fast.
 
I have had that happen to a few of my blades when i quenched them, and i think, note that i`m not entirely certain, that it happens more frequently when the blades are overheated. It might be due to being hotter on one side than the other, and as such affecting the grain-growth in such a way that there`s larger grains on one side of the blade than the other, and then they warp when it hits the quench.
Also, this is just theoretical mind you, if the clay-coating on a blade is thicker on one side than the other, could this also affect it so that one side is cooled slower than the other, and causes it to warp? It could be. I don`t know as i don`t do clay-coated blades.

But i`ve learnt the hard way that steel really doesn`t need to be as hot as i first thought it would need to be. Generally, in my last forge, i was firing the damn thing so hot, that i actually melted a few blades.
 
I straightend a W2 blade right out of the 450 degree temper oven the other day, but is was a totally hardened blade. Did afte the 2nd temper. I discovered that i pretty much need to temper 3 times at 450. I had a little chipping on a hunter after 2. Did the 3rd at 465 and it worked like a charm. Did my big bowie at 465 2x and it came out great. Chopped on a maple board a bit and no damage at all. This W2 apparently either gets screaming hard or not at all....nothing in between....lol
 
RHrocker...
you asked if it was a "W" pattern... i am not sure what you are talking about.. all i did with the blade after it came out of the quence was took the clay off..
so... lots of good advice! thanks guys
~Chris
 
From the looks of the missing piece of steel I would suspect there may have been a crack there before you straightened it. Welcome to the club! With as many blades as I have made stuff like that still happens but not as frequently. You need to get back on the horse and try again......
 
You can put an inch or two, of a tempered blade in the vise, heat with a propane torch on the spine only where you see the warp to be, while over flexing a tad, and pour water on it. Bring the heat to at least a straw color, and be careful to not let it run into the edge. You may have to repeat, but this works very well. Compliments of Bill Moran.
 
LRB said:
You can put an inch or two, of a tempered blade in the vise, heat with a propane torch on the spine only where you see the warp to be, while over flexing a tad, and pour water on it. Bring the heat to at least a straw color, and be careful to not let it run into the edge. You may have to repeat, but this works very well. Compliments of Bill Moran.
Click to expand...
That is what i did, but I did it right out of the temper. No need to use the torch. I just made sure that it wasn't the final temper cycle
 
Knifemaker87 said:
RHrocker...
you asked if it was a "W" pattern... i am not sure what you are talking about.. all i did with the blade after it came out of the quence was took the clay off..
so... lots of good advice! thanks guys
~Chris
Click to expand...

W pattern is a damascus pattern in wich you cut and stack to form bend in the pettern resembling W's. The scale and clay on you blade almost make it lok like damascus.
 
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