Blade warp from Temper??

M

Maineiac1

Joined
May 3, 2017
Messages
339
I just HT'd an O1 knife blank in a Kiln at 1500 degrees for 20 minutes. blade is 1/8" thick, bevel is .45" tall and the edge was left at .023"-.02", 5.5" blade, 4.5" handle. After the quench in canola oil I checked for straightness and was perfect, filed checked good, then I threw it in a Cuisinart toaster oven at 425 for 1 hour and after that I noticed it had a significant warp to the left and the blade was laying on the right side. I tried to straighten but not much success. I then laid the blade on its left side and again at 425 for an hour. After that I quickly bent it straight with a hair warp still in it that the average wouldn't notice, I can tell by laying it on something totally flat and flipping it.

Is it something from the temper process? Ive noticed this before but thought I may have forgot to check after the quench... Hate to waste a good blade and a few hours of work
 
Always temper with blade upright. For now, clamp it to a flat thick piece of steel, maybe over bend slightly the other way and re-temper. No need to waste a good blade.
 
Was the right side directly exposed to the heating element? If so, it heated up (expanded) faster than the left side, which made it curl. So do what Don said, or put a piece of steel in the oven to act as both a thermal mass as well as blocking direct radiative heat - or better yet, do both.
 
Nice tips, thanks. I experimented with the heat from this oven as I use it for kydex also and I found on convection it heats as evenly as I can get it where the coils on the bottom get hot and the top (but not as much) and also there is air circulation... I will try vertical next time and if that fails ill start clamping it.

Ive bent it enough now during the last temper if I lay it on a flat surface I can barely get a piece of paper started under the center (highest point). But may try another clamp and temper.
 
i bent a strip of sheet metal into the shape of an "M" making the point in the center of the M touch the bottom. it stands the blade up in the oven, so the spine is closest to the heating element.
 
john april said:
i bent a strip of sheet metal into the shape of an "M" making the point in the center of the M touch the bottom. it stands the blade up in the oven, so the spine is closest to the heating element.
Click to expand...

great idea, what setting do you use? I have the option of Warm/Bake/Broil/Convection..
Bake??
 
I watched an interview with Martha Stewart once where she said it's only "baking" if it's bread and that otherwise it's "roasting." Therefore tempering of steel is roasting. The weird things that you remember in life... I'm not sure the dictionary necessarily agrees with her though.
 
Larrin said:
I watched an interview with Martha Stewart once where she said it's only "baking" if it's bread and that otherwise it's "roasting." Therefore tempering of steel is roasting. The weird things that you remember in life... I'm not sure the dictionary necessarily agrees with her though.
Click to expand...
Larrin said:
I watched an interview with Martha Stewart once where she said it's only "baking" if it's bread and that otherwise it's "roasting." Therefore tempering of steel is roasting. The weird things that you remember in life... I'm not sure the dictionary necessarily agrees with her though.
Click to expand...


Haha I believe the dictionary would, as I was roasting at 425!
 
I temper blades on there side and never have a warp problem from tempering. If I have a warp or bow it was allrrady there befor the temper. I use a thick sheet of steel in the oven and preheat for around an hr. then I lay the blade right on the steel. This helps regulate the temp of the blade and smooth out any fluctuations and swing in temp.
 
JTknives said:
I temper blades on there side and never have a warp problem from tempering. If I have a warp or bow it was allrrady there befor the temper. I use a thick sheet of steel in the oven and preheat for around an hr. then I lay the blade right on the steel. This helps regulate the temp of the blade and smooth out any fluctuations and swing in temp.
Click to expand...

That's how I do mine. Got a piece of thick flat bar that lives in my oven. Never had a blade come out with a warp.
 
I have the convection fan set up on mine so it stays on when the power is turned on to run constantly and it doesn't seem to "create" any issues. I've not run it with it disconnected, but once mine gets up to temp it maintains a +- .5*. Mind you all the wiring in mine is redone running off a PID and INK BIRD timer when I'm heating full power is going to both the upper and lower elements.
 
I’ve tempered about 30 blades in this oven and this is the second to get a warp. I’m positive they were straight before. I don’t normally use convection or a bar of steel to lay it on, it was on convection since I found that’s what works best for me for Kydex and never changed the setting after. I’ll have to try the steel bar or use the pan that cane with it. I was able to get the blade straight so that’s good news! I was going to try and use my paragon to temper but as you may know as I am new to a kiln is that it takes forever to get from 1500 to 400
 
You must log in or register to reply here.
Back
Top