Drawing back to spring temper with torch

[benjamin2515101]

I plan on using some 1095 for experimenting with making my first slip joint knives. I cannot find any specific information on bringing the metal down to spring temper after quenching. I've read the lead melt pot method, and the method of placing the spring in oil and burning the oil off, but these seem to be too random, since neither temperature is a set value. Can someone offer a better method of giving a slip joint spring the proper temper? I would prefer to use a torch if possible. If I should be using a different steel, I am open to recommendations, but it's difficult to find thin stock in blade steel.

 

[argel55]

temper at 675 degrees for two hours.

 

[Bill DeShivs]

I use 1095 almost exclusively for springs. I quench in canola oil.
If you are using a propane torch, adjust your flame way down and play the flame over the part. Keep the flame moving and watch for the color change to blue. Try to heat the spring evenly to blue. I usually go a shade past blue for my springs. Let the spring cool down to room temperature.
An oxy/acetylene torch is probably too hot for tempering. You need a nice, soft flame for control. Use a firebrick or other heat-reflecting surface to lay the spring on. Using pliers or a vise draws off too much heat.
I have made thousands of springs this way. 3 have broken-and they were all from the same piece of steel.

If you are doing multiple pieces, using a toaster oven to temper is probably the best way to go.

 

[kc custom]

My best efforts are very similar to Bills above. A peacock blue just going into dull sliver. I now have a hardness tester
and when checked they usually Rc out at 47-49 ish. I had a number of springs break in stainless before I had a hardness
tester but never broke a spring made of carbon steel.
Ken.

 

[benjamin2515101]

Thanks guys, that is a great help. I have just seen a lot of variation on information, I wanted some from personal experience.

 

[Don Hanson III]

I do what Bill does, but after the springs have been tempered with the blade/s. I use a propane torch.

 

[Justin Pospesel]

I do what Bill does, but after the springs have been tempered with the blade/s. I use a propane torch.

When you temper your springs with the blades what temperature is that? Are you doing it at a 400 and then using the torch to blue it?
I made two springs out of 1084 carbon that both snapped. I used my forged to heat treat them and used a torch to get them a hair past blue. One snapped on final assembly. Right as I went to work the action it snapped

 

[Stacy E. Apelt - Bladesmith]

10-year-old discussion.

Bill is still around and might pop back in with a reply.

One issue with quick tempering springs with a torch is the temper may only be skin deep. Oven tempering or tray tempering in burning oil are better methods.

 

[Justin Pospesel]

Are there any good tutorials on the oil method

 

[DanF]

Karl B. Anderson posted a video doing just that if I remember correctly.

 

[Stacy E. Apelt - Bladesmith]

Here is a recent thread on tempering 1095 backsprings. I explain Bill Moran's oil pan tempering in the end.:

Thread '1095 tempering for springs'

Oct 24, 2008

Can someone please point me towards some information on tempering a slip joint spring from 1095? I can find information on how to harden it but I'm having some trouble getting information about tempering.

I have heard that you can torch the spring to bring the hardness down but I have been told to torch the front (blade side) or to torch the back side. I've also been told to heat a scrap of steel and use that to transfer heat to the spring.

Thanks for any help.
SDS

• SDS
• Replies: 9
• Forum: Shop Talk - BladeSmith Questions and Answers

 

[Bill DeShivs]

There seems to be some confusion about "tempering." I only mentioned a toaster oven if you are doing several springs at once. The oven is used instead of a torch.
Tempering is done after hardening. Tempering draws the steel back in hardness.
Quite simply-after hardening fully- I clean the spring to bare metal, lay it on firebrick, and play a propane torch at low heat (very low) over the spring as evenly as possible. You may have to spend more time on thicker areas of the spring. Bring the entire piece to just past bright blue, and let it cool. If you get it hotter it will lose flexibility. If you don't get it hot enough, the spring will be too hard.
This may require some practice, but it's not hard to do.
It's very unscientific, but it works.
My work is on individual knives, so the torch is easiest for me.

 

[weo]

If you are using your forge to HT, depending on the type of forge, the shell might be hot enough to temper them by putting them on top of the forge and watch for the color change (after cleaning to bare metal). Have a can of water ready to drop them into as soon as they get the color you want.

 

[hodgescl]

If you have an older stove with the coil element you can get turn that on high and set your part on the element until it turns the color you want. I use it to temper the tangs or the spine of a really wide blade sometimes.