Questions on ( historically correct) blade tempering from a beginner

M

Mr. Standfast

Joined
Aug 12, 2008
Messages
53
Hello,

I am making a pocket knife based on the construction and style of those made during the Civil War era (built from scratch and I'm trying to make it as historically correct as much as possible).

I have finished the handle and my brother tempered the spring for me, but he doesn't know how to temper blades. Since this is a reproduction I want it to be tempered with methods used in the CW era.

But before I get into that, shouldn't the blade be annealed before tempering? I didn't hand hammer out the blade (I ground it, not authentic I know:rolleyes:), but I did have to heat it up about seven times to stamp the nail groove in the blade. A blacksmith told me he thought it might be a good idea to anneal to reduce strain and to keep it from getting brittle (he is not a knife maker though!). So, should I anneal it and how is this done?

Now questions on the actual tempering of the blade. I was going to use an old Sheffield recipe, but I want to see if it makes sense first (remember I'm a complete ignoramus). Here it is:

"After the marking, the blade is hardened by heating it red, and immersing it in water. In this state it is too hard for use, and requires tempering. The blade is now rubbed bright on one side with sand-stone, in order that the progress of the tempering might be seen. It is then placed with back downward on a plate of sheet-iron, which is put on the fire, and the workman very attentively watches the changes of color in the blade, till they attain to a straw colour approaching a brown, which is the test of the proper degree of temper; he then slacks(slakes) it to arrest further change."

Things that don't make sense (yet)
1. I'm assuming the blade is heated red and immersed in water after annealing if that is done?
2. Approximately how thin/thick is the sheet metal supposed to be that the blade is on while being heated?
3. End of process, slaked in what, oil?

If you can help me with any of this that would be great!
 
Last edited:
First, it would help to know what steel it is. Second, a simple water quench is not recommended. Too much chance of it breaking, cracking, or forming micro cracks. Color tempering is a poor way of tempering. your kitchen range would do better. Without knowing what the steel is, it would be difficult to recommend a proper heat treat. Do you know what the steel is?
 
With-out knowing the steel it would be a tough one.
On most 10-- series steels this simple method should work
Heat the blade to critical (where a magnet will not stick) let it air cool.Do this 3 times
heat the blade to critical again and place it in bakealite or wrap in insowool and let it cool as slow as possible. 6-8 hrs
set up a quench tank (can be a metal pan) fill with peanut oil till about half as deep as the blade is wide (from spine to edge)heat to about 100 deg F
Heat the blade to just above critical again and put the blade in the quench, edge down , starting at the point and rocking to the tang.Do this quickly. Keep rocking the blade from tip to tang until all color is gone from the blade then submurge the rest of the blade in the oil and let it cool. You can check edge hardness with a file. See if a file will cut the steel or if it just skates across. Try a couple times with the file the first couple swipes may just be decarb if the file skates its hard.
Have a oven (or toaster oven pre heated to 450 deg F, ) place the blade in the oven edge up for 2hrs. remove blade final grind and sharpen
I don't know what tools you have but this is a primative rough HT & temper.
Hope this helps many others may have better ways.This is just basic.
 
The carbon steel is D2 according to my brother (he got a lot of my materials for me, now I'm on my own though;)).
 
If your going to try the recipe you showed above I would suggest you use a water quenching steel such as W2 But you can do it with 5160 and quench in oil...A half inch plate should work as long as your using a coal or charcoal fire,this method wont work with gas...The slacking means to quickly quench the blade in a bucket of water after reaching the desired straw brown color,the reason they call it slacking is that the blacksmiths call the bucket of water they keep near the forge a slack bucket..

Good Luck,
Bruce
 
D2 is one of the worst possible choices you could select for making a knife by the method you desire. It is an air-hardening (read: NOT water) high alloy steel which requires extended heating at a very specific temperature well above "red" and is intended for use with higher technology like heat treat furnaces or molten salt baths. It also requires at least two tempering cycles of 2 hours apiece to properly temper (draw) the hardness back to a usable level.
You need to change steels.
 
Last edited:
:D I don't think D2 was readily available during that time period :D

However blade could have been ground (stock removal) back then, starting with a flat piece of steel.

However, if you have your heart set on using that D2 blade you've already put much physical and emotional investment in; I would send the blade out to be heat treated and cryo treated with modern methods.

There are plenty of sources for the 10xx series steels that you could heat treat in the 'traditional' manner. I could be talked into sharing some of my 1075-1080 steel that is in my shop (especially since I have over 100lbs of the new 1084 that my nice UPS guy carried up the stairs over the last few days :eek:)
 
Joe Cabaup said:
:D I don't think D2 was readily available during that time period :D
Click to expand...


Everybody, thanks for being "brutally" honest.;) I will tell you the truth and say that I have collected these old knives for some time, and know how they are put together and what shape the parts are, but I know absolutely nothing about steel (a very slight exaggeration).

It looks like the next knife I make will be more authentic, as I will take the recommendations you-all gave and use the correct steel for this particular process.

Mr. Cabaup, where would you send a blade of D2 to be tempered? The blade must go into the pocket knife as the process is too far along. I have been working on this knife for a long time, and it would crush me if I warped the blade or made some other mistake! It's coming out so well thus far.
 
Mr. Standfast.

When I was working with D2 I had the heat and cryo done by another knifemaker, who doesn't offer that service any more. A quick internet search shows that Texas Knifemaker still offers the heat and cryo service for under $10.00.

The MAN to go to though would be Paul Bos but I've never worked or contacted him as I've moved to simple carbon steels. I am sure (and hope) others will know of resources I don't know about and post them for us to see.

BTW, the last D2 blade I had heat and cryo'ed is still in the shop, wearing away the grinding belts. I wasn't happy with the profile and I've been trying to thin it down for the last two years. Once I get it to where I am happy I am sure it will last forever.
 
Thanks Firebart. I think I'm all set now.

I appreciate everybody's help and advice getting me on the right track. Thanks!
 
Just a note about your spring, if the temper is not correct your folder will be junk. If not tempered properly the spring will either break or bend. After the knife is assembled this is really dissapointing. I know because I did not get the right temper on my first folder spring.

To test the spring you can mount the spring and blade on a hard surface such a micarta or really hard wood or a piece of steel. Just drill pin holes like you plan for your liners. Then you can flex the spring and fit the blade in the open and see if the spring in really a spring. I may have a photo of a setup if you need.

good luck
 
You must log in or register to reply here.
Back
Top