Temper mistake?

Nick EBK

Nick EBK

Joined
Nov 25, 2015
Messages
66
So this is a Christmas knife, for my cousin. The fit and finish isn't amazing, there are small scratches and whatnot (made worse by the camera). When I went to temper, I used a new toas- umm temper oven. I tried to be cautious and set it to 425f, but I ended up getting plums and blues, mostly in the handle. Now, this blade looks and feels sharp, but no matter what I do, it will not get shave/papercut sharp. Am I correct in thinking that this is due to overheating on the temper? Sorry if this is an obvious question, but I haven't actually gotten blues before.

1084, black palm, attempted hamon, hot vinegar etch.

2015-12-17 14.14.12.jpg
 
Tough question to answer. Temper colors are a poor judge of temperature unless you start with perfect clean steel. You may have over heated, maybe not. Still should be in the 56-57 range even if you made it to 500. Unless that's built off of 3/32 stock, your edge bevel is pretty thick. Thick like that, it would be hard to slice paper even if it was sharp and full hardness.
 
Do you have a separate temperature gauge inside the oven? toaster ovens and home ovens can be off by a lot compared to what they are set at it seems
 
The main bevel is roughly 25 degrees, its 1/8 stock. I took the cutting edge to 20 using a lansky set. I could try the lansky set again, starting a grit lower... If that is still too thick, I'll just tell my cousin it's a micro chopper! :D

Do you have a separate temperature gauge inside the oven?
Click to expand...
I do not... normally I would use my super cheap oven, and dial it in to 450 using an infrared thermometer, before I began to temper. But this time I tried to use the convenient in-home one. It will be nice when my PID stuff gets here.
 
Most likely a geometry issue. On the next one bring the bevels up at least to 75% height, preferable to full flat.
 
Maybe I'm wrong, but poor temper wouldn't effect it's ability to cut paper, but would effect it's ability to cut it more than once. A poor temper would effect edge retention. I agree with the others that it is an issue with geometry. For a mini-chopper it would be a good edge, but a poor edge for shaving or slicing.
 
If you are using a toaster oven, just get a cheap oven thermometer, its about 5$ and will give you relatively accurate temps. I would always set for a lower temp than you want, that way if it goes higher (almost always) it wont affect the temper you want. Dont worry about the colour, anything can affect that. I have a toaster oven I use for one or two blades but otherwise I use my kitchen oven. If you really want to be careful, a pan of sand will help regulate your temps (barring using a full PID setup).
 
Well I'm glad everyone mostly agrees that it's a geometry issue. This was a test knife on several fronts, which is why it's a gift and doesn't have my maker's mark... I liked making this simple design, and I'll take the grind up a great deal higher next time.
 
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