Temper 1080 for slipjoint spring.

coachcampana

coachcampana

Well-Known Member
I got my kiln, and slipjoints have been on my list to try once I got caught up on other orders. Is there a general time and temp for most steel that needs to be a spring? I've been looking online and can't find much.

Thanks !

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For 1095 I'll normally do a reguar temper cycle withe blades and springs together at about 400F (2 cycles at about 60 to 90 minutes each), then for the final spring temper I'll use a hand torch to draw it to a deep blue/purple. If using an oven I'll set it to about 670F or so. 1080 should work about the same
 
ARCustomKnives said:
For 1095 I'll normally do a reguar temper cycle withe blades and springs together at about 400F (2 cycles at about 60 to 90 minutes each), then for the final spring temper I'll use a hand torch to draw it to a deep blue/purple. If using an oven I'll set it to about 670F or so. 1080 should work about the same
Click to expand...
Oh man, thanks! With my first prototype I did the hand torch/draw to blue technique, that worked fine. However, it was super easy to mess up. I figured since I have the kiln now, there should be a better way.
How long do you leave the spring in the oven at that temp? Thanks again for sharing your information. Huge help.
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coachcampana said:
Oh man, thanks! With my first prototype I did the hand torch/draw to blue technique, that worked fine. However, it was super easy to mess up. I figured since I have the kiln now, there should be a better way.
How long do you leave the spring in the oven at that temp? Thanks again for sharing your information. Huge help.
Sent from my XT1565 using Tapatalk
Click to expand...

Long enough to hit blue would probably be ok, as long as it's been through a 1hr temper cycle or two. In the past, I've done a 1hr "snap" temper at 400F along with the blade, and then when my kiln cooled down enough from the initial heat treat temps, I'd do another 45 minutes at around 670F just to be thorough. Chances are (especially given the smaller size of the spring) that it'd be ok if it came out a little faster, but it certainly doesn't hurt to leave in a little longer either.
Lately, I've just been doing a couple of 1hr tempers with the blade at 400F and then doing a final draw with the torch on the spring, and that seeems to work just fine.

Someone else may have some different times that work as well or better, or at least a better explanation, but this is what has worked for me.
 
I have never had a carbon steel spring that snapped or that gave for too much softness. I temper thoroughly the spring with the blade (380-420 °C depending on the steel), and then draw the spring to light blue only in the flex portion, including the first hole, with a soft propane flame, taking time and care. I leave the walk of the spring (the part that engages the tang) hard as much or only slightly softer than the tang.
My concern would be if the oven spring tempering would lead to gall the "walk" spring portion with the much harder tang in the long run.
For a spring the important and foremost thing is an even lath structure and a through tempering, a couple of hrc point less would add more toughness for the ease of mind, hence the drawing to blue, but if the microstructure is sound, a well designed slippy spring could be used even in high hardness range. I tested springs for destruction and trust me....those snapped springs you hear about in slipjoint horror stories most likely had troubles before even going into tempering!
I consider this subject (in theory) a point for carbon steels over the stainless, for this application. I wouldn't selectively temper stainless as easily as the carbon steels.
1080, btw goes for a very nice spring.
If you go for the oven tempering please tell me if you have galling (sp. galding?) or not...oiling the joint of course
 
stezann said:
I have never had a carbon steel spring that snapped or that gave for too much softness. I temper thoroughly the spring with the blade (380-420 °C depending on the steel), and then draw the spring to light blue only in the flex portion, including the first hole, with a soft propane flame, taking time and care. I leave the walk of the spring (the part that engages the tang) hard as much or only slightly softer than the tang.
My concern would be if the oven spring tempering would lead to gall the "walk" spring portion with the much harder tang in the long run.
For a spring the important and foremost thing is an even lath structure and a through tempering, a couple of hrc point less would add more toughness for the ease of mind, hence the drawing to blue, but if the microstructure is sound, a well designed slippy spring could be used even in high hardness range. I tested springs for destruction and trust me....those snapped springs you hear about in slipjoint horror stories most likely had troubles before even going into tempering!
I consider this subject (in theory) a point for carbon steels over the stainless, for this application. I wouldn't selectively temper stainless as easily as the carbon steels.
1080, btw goes for a very nice spring.
If you go for the oven tempering please tell me if you have galling (sp. galding?) or not...oiling the joint of course
Click to expand...

I have also wondered about potential galling/wear of the softer spring. That's one reason I opt for the torch method, as I do much the same, trying to leave the tang end of the spring untouched. That said, I also make sure to polish both surfaces as much as I can, and have a good radius on the corners of the tang, to reduce wear/friction as much as possible there as well.

Now, whether there's a noticeable difference, I haven't really tested. I know production folders don't really account for this, and there doesn't seem to be a problem there, but it is always in the back of my mind.
 
As a folder maker I find this very interesting.

I don't know if it's luck or skill, but I have only had one spring fail on an early folder. Looking back I agree with Stefan that design had to have had some part in its failure because it failed after about 6 months of use.

the idea of tempering a spring differenchally is interesting. Having a better hard to hard surface intellectually seam like a good thing. My concern comes in on having a transition zone from hard to flexible that could add a tremendous stress point that could fail.

i have had folders come back for service and haven't noticed any trouble with gauling that changed the walk an talk smoothness so far. I too string temper with a torch but to a light blue well back through the first spring hole.

This is sounds like a chance to do some testing for all of us. Never can stop learning!

Erik
 
Thanks for taking the time to post fellas. After reading what you're saying, I think I'll just stick to the propane torch and draw to blue. I'll just have to practice more to get comfortable with it.

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I must add that i don't have so many springs under my belt to be sure i wasn't just lucky up today; but i underline that first step is subjecting the spring to a full temper, only then i draw the flex portion + central hole, to blue. Considering the minimum required flex range i'd say i don't see radical failure points in the transition area. Even the tempered blade, at those thickness could be flexed those little amounts.

As far as the galding another question mark is the finish... i sand the contact areas up to 2000g, but somebody suggest a coarser finish (lenghtway) to "retain" more oil and ensure smoother walk and talk.
A lot of subtle details...make the slipjoint builds a very interesting journey.
 
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