Blade thickness...or...did I grind too much?

R

Ryan S

Joined
May 6, 2004
Messages
1
Have a blade I'm trying to grind out. Started as 1/8" thick O1. OAL is about 11", blade is about 5.5". have to dig out a pic I think at some point to describe the shape. Starts about 7/8" deep to 1" at the deepest part of the belly before angling back. Spine is straight. Shape wasn't what I had in mind to begin with, but hey...it's just a hobby right...... :eek:

Now i've gotten it ground out how I want, but it seems...thin. I mic'd it and it's about .110" thick now near the spine, and gets about to .96 nearing the tip. I tapered it just a hair at the spine. Tang is tapered. drilled a bunch of holes to save some weight as well. kinda messy...will have to do that a bit better next time.

Enough blather, did I grind it too thin? I did the ol' backyard firebrick and propane HT, passes a file test, tempered it at 400 for an hour, twice (using an over thermometer in the toaster oven). Should I go for 425/450 instead maybe? Or am I just being an overly worried newbie?

blade-1.jpg
 
Well, I wouldn't temper it any more than 400 degrees. The blades I have done in 0-1 hold a better edge at a lower temper. I have been tempeing at 375 to 400.

As far as the too thin issue, dont worry to much about it. If it were too thick then shoulders of the edge bevel would be too steep to cut nice and clean.

At this point I would put a temorary edge on it and chop some 2 x's to see if the edge chips out from being thin. It really all depends on what you will use it for.

If you have a caliper measure the edge. it should be about .015 to .025. Some choppers are .030 if I remenber correctly.

Hope that helped.....
 
Ryan, that's not too thin at all, especially if you are making a cutting knife instead of a crowbar. There's a reason the most used knives of all, kitchen cutlery, are thin.

As far as tempering, in addition to a file test, it is good to learn the "brass rod test".

Search the archive here and CKD.... you'll find this method of testing flexion of the edge to read tempering efficacy.

Another thing to search out is something called the "Golden Rule", I believe. It is an architectural rule of symmetry that can help one get the proper ratio of handle length to blade. It is worth reading about. A quarter inch in handle length can change the whole appearance of a knife.
 
bl is right. Your 400 F temper is fine. Temper at 400 F and you can drop the second 1 hour temper down to 375 F.

I don't see a thing wrong with the drill holes in the tang. Looks like you did that well.

RL
 
fitzo said:
Ahhh, "Golden Section". Thanks, Mr. Mike!
Click to expand...

Excellent, Mike and Mike. Also called the "Divine Ratio" and the "Golden Ratio".

The ratio of 1 to 1.618, used throughout the universe by the divine architect.

Given the knowledge of this ratio, there is absolutely no doubt that all matter was created by design, and that we are not simply an accident of chaos.
:)

Sorry for sermonizing. "Nough said. :D
 
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