440c and autos

[T. Hendrickson]

I want to make an automatic knife. I have 2 questions.

1. To what temperature should I temper 440c for a leaf spring on an automatic?

2. What kind of release mechanism is best for a leaf-spring auto?

Thank you all very much and I look forward to your thoughts.

[T. Hendrickson]

any thoughts???

[Ray Rogers]

I don't think many of us make automatic knives. The ones that do may make other styles than leaf spring knives.

But, if you temper 440C between 1000 and 1100 F you are supposed to get a Rockwell of mid 50's to low 40's. This is only a 100 degree range which makes a huge difference in the hardness of the steel. Generally, spring hardness is in the high 40's or very low 50's in carbon steels. I think it should be the same for stainless but you'll have to experiment to see what works best with your equipment since that temperature range is so narrow.

Again, not making autos I can't speak with any aauthority on what release mechanism is best but I think I would have to paraphrase my Kung Fu teacher on this. When someone would ask him which style of martial art was 'the best' he would say, 'The one you master.'. That's how I see this question, i.e., any mechanism you can build should be fine .......

[T. Hendrickson]

thanks ray.

It was just a whim of mine to experiment with this. It sounded interesting, so I drew up some plans and this is where I am stuck.
Now, I know that autos are not the best using knives and that many liner lockers can be just as fast, but I just wanted to do it so that I could say that I did it!
So, what are the other opening mechanisms aside from the leaf spring? What method does Chris Crawford use? What release mechanism does he use? I wish Crawford would make a pamphlet on his mechanism that I could buy, because I don't have a dvd or vhs player or television.

[Ray Rogers]

I don't know what spring mechanism he uses but a Mini-Reflex that I used to have (made by Benchmade) used a tiny coil spring wrapped around the pivot.

I think Crawford's knives use a bolster release but I have no idea how that works.

No tv, vcr, or DVD player? Man, and I thought I was in the sticks! My best advice on how to approach that problem would be simply to take your own good advice from your tag line .... 'find a way'

[HermanKnives]

I would not use 440c for the leaf spring. J. W. Smith and I both use ats34 and have never had one break but I now use 17-4 ph ss as it is made as a spring steel and is very springy in the annealed state. I even switched from titanium for my inlaid linerlock type springs to 17-4 as it isnt sticky like ti.
The heat treat for ats34 for springs if you want to try it is 1975 then temper at 1140 twice at 2 hours each temper.
Heat treat for 440c spring temper That I got from Wolf Loerchner is 1875 then temper at 1000-1050 and should get about 51 RC.

Good luck.

[joe delellis]

I have made several auto's using the button release design
with coil spring.Bolster needs to be 1/4 thick minimum.Leaf spring should be heat treated to 44 / 46 rockwell c.

[Geno]

The scale release is my favorite design in an auto.
Kick spring will work just fine, but why not try thr s/s spring stock from TKS?
316 s/s spring stock premade, just cut to length and/or bend as neccessary.No h/t required.Go to the CKD link to TKS.You can order it online.

[joe delellis]

geno Ineed e mail address of "tks" to order pre h/t spring stock. thanks joe

[Geno]

Joe, just hit the scoll arrow down.
At the bottom of the page is a banner link to Texas Knifemaker's supply, click on it.Your there.
TKS is one of our sponsors here.

[Bob Sigmon]

If you're having troulbe finding the link here it is. . . . .Texas Knifemakers Supply

Bob Sigmon

[Geno]

Thanks Bob,
Remember that I am a computer dummy.
Can't do links, pics, ect...I just talk.
That's me, the talker!
Talk, talk, talk,talk.......
Kinda like the teacher on the Charlie Brown cartoons.