Four strikes, but still swinging

M

me2

Joined
Oct 11, 2003
Messages
5,112
Ruined my 4th blade during HT a little while ago. So far I'm 3 and 4 out of the 7 I've tried at home. But I learned from my mistakes, so its not a loss, just a setback. I keep saying the same thing about a particular ex-girlfriend.

For those interested, the blade was 1/16" thick, 5/8" wide, and 3" long with a stick tang. Steel was from a Nicholson Black Diamond file, softened and ground to shape with a full flat grind and a slight drop point. Blade was probably ground too thin for quenching, I'll be using oil now, whether the steel is water hardening or not, and it may have been overheated slightly. The fracture surfaces were smooth, but not as smooth as they were on the last one I did right. The point also ended up a trailing point after the quench. I was using a one brick forge and Mapp gas to heat the blade. Looked like good even heating, no twisting or curling like my first blade done that way. File just knocked the scale off the edge. Oh well, back to the drawing board.
 
Been there done that! can't tell you how many pieces of A2 and 01 I wasted before I ended up with a blade that I was actually proud to keep! Not forging my blades but man back in the days,...it was like ooops...welp, there's another paper weight! Sometimes they were salvagable and most of the time NOT! Just keep at it. I think I read earlier that a blade cracking might be caused by the blade being too hot when it's quenched. I have no idea how a nicholson file would act after it's hardened, then softened, and then hardened and then quenched again.

I'm guessing the pros will jump in soon! keep at it and don't get discouraged! It's all a learning experience!

Best of luck on your next blades!

Pohan
 
me2,

You need a cutting edge at least a 1/16th or more thick when you quiench. Use oil unless you are really experienced. Water is reallt harsh. Heat the oil to around 125 degrees. You can do that by dropping in a hot piece of steel.

Carefully judge your heat. Forget color, use a magnet. Heat to just a bit above non magnetic and quench. Draw temper as soon as you can afterwards, to a dark straw (dark yellow brown) color. Unless you have a toater oven you can use. that makes life easier.

Water should be used only as a last resort because it has a high, and expensive learning curve.

Good luck,

Gene
 
I thought I'd messed up a blade about as many ways as possible, but this one was new. There were about 4 little cracks right at the edge, but not all the way through. If 1/16" is the edge thickness I'm aiming for before quenching, then all my grinding would have to be done after hardening. Nothing against it, I just dont have the equipment to do it in less than a year. I was aiming for 1/32 before quenching, but after everything was done, it was more like 1/64". I left the surface pretty coarse too, so that was probably a bad idea. I saw some experiments that have super fine grain 1080 steel hardening fully up to about 3/32" when quenched in oil. That appears to be the way to go. The last blade I hardened in water warped a little, but didnt crack. It was a kiridashi, with a chisel edge down to about 1/64" or so, not quite sharp, but not much to do after hardening either. My blades arent big enough to use as paperweights, so their only real use is to serve as a bad example.
 
The reason for the thickness on the edge is that your heat will burn some of the carbon out of the surface of the steel. If you do not somehow shied the steel via coating, ss foil envelope or inert atmosphere, the surface and thin edge will be no good and not fully hard. If you want to keep down on the post hardening grinding I suggest you get some PBC and heat the blade to about 700f then coat it liberally and then take it to 1500f and quench, That way you could start with the blade near its finished state. I would suggest that you leave the edge a bit thicker if not protected and a bit smoother finish will help keep cracks from starting. I also agree that you need to check with a magnet and then get it just a bit hotter as you even the heat along the blade. Too hot when quenching is bad for cracks and large grain. Good luck Jim
 
Quench in oil - Forget water for a long time.

Start with a larger knife - the scalpel type you were working on is fraught with quenching and grinding problems. A simple ,full tang,drop point hunter,about 6-8" OAL is a good starter knife.

Start with thicker blades - 1/8" is the thinnest you want to learn on.

Have thicker edges at quench - .03-.04 is what you want.

Control your heat - A one brick is the cheapest forge, but has no real control. The blade will need to be evenly heated,and at a precise temperature. As soon as possible build a simple tunnel forge. You will be amazed at the difference.Cost is usually less than $100 to build one, often much less.

Get a known and first use steel - while the temptation to re-use found items is great, a piece of 1084 would be much cheaper in the long run. And it is real low in price anyway.

What all this boils down to is - START SIMPLE AND WORK UP TO HARD

Stacy
 
an important thing is to keep notes on your process so you can change known variables. when i first started i'd repeat my mistakes because i wasn't sure what i was changing in my ht processes.

Will
Formerly known as badbamaump
 
bladsmth said:
Quench in oil - Forget water for a long time.

Start with a larger knife - the scalpel type you were working on is fraught with quenching and grinding problems. A simple ,full tang,drop point hunter,about 6-8" OAL is a good starter knife.

Start with thicker blades - 1/8" is the thinnest you want to learn on.

Have thicker edges at quench - .03-.04 is what you want.

Control your heat - A one brick is the cheapest forge, but has no real control. The blade will need to be evenly heated,and at a precise temperature. As soon as possible build a simple tunnel forge. You will be amazed at the difference.Cost is usually less than $100 to build one, often much less.

Get a known and first use steel - while the temptation to re-use found items is great, a piece of 1084 would be much cheaper in the long run. And it is real low in price anyway.

What all this boils down to is - START SIMPLE AND WORK UP TO HARD

Stacy
Click to expand...

Yep, what Stacy said. If you cant regrind after heat treat you should look into a grinder that will. I dont even bevel 1/16" steel until after its hardened. Also buy some steel or ask around here for some. Dont get discouraged, just learn from it all.
 
Another way to look at it is...If you grind after heat treat and tempering, you would do less grinding, than if you were grinding the steel before and after heat treat(in theory). Are you forging to rough shape or grinding flat stock? There can be an advantage to forging to rough shape and then heat treating. after tempering you would have to watch heat build up when grinding but it night be a little less work for ya in the long run...
 
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