Please help!!!

R

Razor Back

Joined
Nov 11, 2016
Messages
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Ok guys, first off thanks in advance for any advice. I need some help in a bad way!! I have been making knives for awhile now but by no means am I any kind of expert. I could stand to learn a great deal more. I am using .064 1095 wear resistance spring steel. Have been for quite a while now with no issues. Now all of a sudden my blades are cracking!!! In short here is my method
Shape blade, with grinder
Do rough bevel shape
Heat up to just under non magnetic to apply my makers mark
Heat to non magnetic and quench in pre heated cooking oil
After file test, finish grind bevel being sure not to over heat
Buff to mirror finish, again being sure not too over heat, or do a vinagar wash
Apply handle

Obviously this is a condensed version, I will be happy to go into more detail if necessary. My last four blades have just cracked with no warning. I know that I am skipping a themper step but I have never needed it in the past. I'm not sure if I have just be lucky or what?? I have made 30+ knives over the years for friends and family and they have always held up great. One is 7 years old and has cleaned 10 or more deer and holds a good edge!! No deveation in my build process. And now they are just breaking. Please help!!
 
It sounds like in the past you were not getting a good hard HT, and the last few you've got good HT which does REQUIRE a temper step. i.e. in the past perhaps your HT was getting 58 Rc (?) which might "get by" without temper. This time you could have got a good hard HT which gave 65 Rc which most likely would cause the cracking you're mentioned if you don't temper.

Ken H>
 
Ken H> said:
It sounds like in the past you were not getting a good hard HT, and the last few you've got good HT which does REQUIRE a temper step. i.e. in the past perhaps your HT was getting 58 Rc (?) which might "get by" without temper. This time you could have got a good hard HT which gave 65 Rc which most likely would cause the cracking you're mentioned if you don't temper.

Ken H>
Click to expand...
Agreed +1
 
Yes, I even changed to a different piece of steel once the third blade broke. Still same outcome. Has to be something I'm doing wrong!
 
Ok, thanks guys!! At least I'm on track to fixing the issue!! Having a blade snap that I have invested 10 hours in sucks!!! Can someone suggest a temper process that would work best for my steel and ht methods?
 
After ht and still warm put it in a preheated oven 400-450°, for 2 hours quench in water and do that again. Thats it
 
Personally I would do 400-450 for 2 hours twice letting cool to room temp in ambient air in between. Works with my spring steel.
 
Have not used much 1095, so not 100% on the tempering temps, but otherwise correct. If you can find a toaster oven at a flea market that works they make decent tempering ovens. Get a toaster oven, put a 1/4" or so piece of mild steel in the tray to help even out temps, use a separate oven thermometer to set your temps, after the oven cycles a few times and evens out on the correct temp put your blades in. I normally do 3 temper cycles at 2 hours each, letting the blades cool to room temp between cycles. Do at least two 1 hour temper cycles and you should be good.
 
I guess my question would be, WHEN are they breaking. Are they breaking in the quench, shortly after the quench, or during use after finishing? 1095 straight out of the quench, provided that the heat treat worked properly, should be too brittle and chippy to use without tempering.
 
They are not all breaking in the same place, and are not breaking at the same time. One broke while peening brass in handle, one just cracked while buffing to shine, the others I broke trying to see how many blades I've screwed up on. None have ever drove in the quench. And one of my little things I do is right after quench and blade is back to room temp, I file test and then chop on a 4x6 block to make sure I get no edge deformations. All have passed with flying colors and then later in the process Bang!!
 
Razor Back said:
They are not all breaking in the same place, and are not breaking at the same time. One broke while peening brass in handle, one just cracked while buffing to shine, the others I broke trying to see how many blades I've screwed up on. None have ever drove in the quench. And one of my little things I do is right after quench and blade is back to room temp, I file test and then chop on a 4x6 block to make sure I get no edge deformations. All have passed with flying colors and then later in the process Bang!!
Click to expand...

Well congratulations! It sounds as if you have gotten better at the hardening of your knives. This is a good thing! Once you get the tempering down you will notice that your knives will perform better than any others have previously. A solid hardening and tempering of spring steel will hold a decent edge and be slightly flexible.
 
So, you are chopping before tempering the blade? My guess would be this being the issue. Since it is very brittle right after the quench and hardening, i think that it's very likely that you give your blades little stress cracks with chopping on a block without tempering it beforehand.
 
10-4 I will go pick up a little toaster oven and get back after it!! Thanks again to everyone!! One more question, how do you test a blade (non destructive) after temper. Is there a way to check and see if the temper is right? Perfably without giving to a friend to have it fail later?
 
If you were not tempering your blades, you should be questioning the hardness of the ones that didn't break. Conversely, if they were hard enough, I would be worried that they will break in use. NOT GOOD.
 
Razor Back said:
Heat to non magnetic and quench in pre heated cooking oil
After file test, finish grind bevel being sure not to over heat
Buff to mirror finish, again being sure not too over heat, or do a vinagar wash
Apply handle

Obviously this is a condensed version, I will be happy to go into more detail if necessary. My last four blades have just cracked with no warning. I know that I am skipping a themper step but I have never needed it in the past. I'm not sure if I have just be lucky or what?? I have made 30+ knives over the years for friends and family and they have always held up great. One is 7 years old and has cleaned 10 or more deer and holds a good edge!! No deveation in my build process. And now they are just breaking. Please help!!
Click to expand...


Heat to non magnetic and quench in pre heated cooking oil
That's important

You're not getting it hot enough.

Because you had incomplete hardening, it was less prone to cracking.
Properly hardened Hard 1095 is SO breakable



If you KNOW you are skipping a temper step, they WHY skip it?
Blades not breaking without temper should have been a clue to examine your hardening process for failure.

The source of your info was bad, time to get new info



Try some 1084, it's better for eyeball heat treat.

Read the stickies by Kevin Cashon for temps, and why
eutectoid and hypereutectoid
 
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