Slipjoint blade thickness

R

Randy3000

Joined
Jun 3, 2017
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I have been using 3/32" steel for 2 overlapping blades on a 3.5" overall length knife. The blades have a little flex to them, but not too much. I actually kind of like this thickness. I grind them asymmetrically where the thickness at the tip is about 1/2 to 2/3 as thick as the base, depending on if it is a full length blade or not. So something like 0.060" at the base to 0.035" at the tip and then finish sanding after heat treat on a slack belt and make sure blades pass each other.

Some of my friends do not share the same appreciation for thin blades. I am thinking about trying 1/8" steel or maybe even thicker. Just curious what thickness you guys like?
 
As a user....

I like both. If i had to choose 1, it would be 3/32. If I could design my own, I wokld make a two blade wharncliff trapper. The clip would be 1/8 and the wharncliff would be 3/32. Or a stockman with the two small blades the 3/32, not unlike the GEC 81 stockman.

The thinner blades are better for slicing, cutting cardboard etc, while the thicker is stouter, less flex, yet still thin enough to slice an onion.
 
Traditional slipjoint design was meant to be thin. The intended purpose and use of the knife should dictate material selection. I much prefer a thin blade material 3/32" which will be plenty strong for most slipjoint cutting tasks. If I wanted or needed thicker material then I would consider a different style knife like a small fixed blade. The slipjoint was created long ago to transition from Bulky Belt Carry Sheath(think hunters, outdoorsmen,trappers) to Citified Office workers who needed a small string cutter that fit a pocket without being bulky.

That GEC 81 Stockman is a very fine example...
 
I like 3/32, maybe 7/64" would be the thickest
here are two different blades, both 3/32"
the profile and grind can have an impact on the way the friends feel about the same thickness

zdTl8U2.jpg


mOIorp8.jpg
 
HSC /// said:
I like 3/32, maybe 7/64" would be the thickest
here are two different blades, both 3/32"
the profile and grind can have an impact on the way the friends feel about the same thickness

zdTl8U2.jpg


mOIorp8.jpg
Click to expand...

Well, the question is about two overlapping blades that have to fit in a single space. So each blade loses half its starting thickness, on average, over the blade length. So 3/32" steel gives on average 3/64" thick blades, 1/8" steel gives 1/16" thick blades, and so on. Asymmetrical grinding makes the blades thicker at the base and thinner at the tip, so the two right triangluar blades fit together to form a rectangle the same thickness as the stock steel thickness and backspring thickness. The asymmetrical grinds make the blades stiffer feeling than if you were to have uniform thick blades, since the bases are thicker.

So what i guess i am asking is at what point is the backspring so wide it all just looks and feels dumb?

I prefer 3/32 and doing things the way i am now, but if someone tells me it is too thin i have to either do what they want or just flat out refuse.
 
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I can't give measures, but you can have a thick backspring and an ok knife if you have thin liners/scales.
Personally i am not too much happy when a knife thickness starts to approach its height, one of the reasons i like single or 2 opposing blades models.
The benfit of having two blades in my opinion is that one of them can be very thin, for delicate tasks. Often a catch bit is included in the design, to allow for a difference in opposing blades thicknesses or to simply give more cleareance when you don't want asimmetrical grinds and same thicknesses.
 
While I make the bulk of my folders with 3/32" steel, I am in no way against using 1/16" thick steel. To
me they can get clubby pretty fast on a slipjoint the thicker they are. I actually like using the thinner steel
and the one in my pocket for the last couple of years is a 1/16" thick sheepfoot. I have also not broke any
blades on steel this thin. Day in, and day out, I don't baby them
Ken.
 
The liner thickness, is just as important. Honestly most makers use way too thick liners IMO, but I understand, because it's a lot easier to work with. Once you get around 0.040 thick, stainless wont stick to most mag chucks, and even a little uneven pressure lapping or grinding will cause things to go out of flat, however, considering you've got 2+ of these on every knife, the extra thickness adds up real quick. Compound that with thicker than necessary bolsters and liners, and really, the blade thickness (within reason) is the least of most knives problem. They get chunky fast.

I also like very thin, and sleek slipjoints, and many antique ones had 1/16 or thinner auxiliary blades, however, in a single spring, multi-blade, ground to clear, there's nothing wrong with using 1/8" thickness for the spring and tangs, just make sure and keep the rest of it as thin as possible.

Also, if a customer is telling you that a slipjoint blade is too thin, and it's over 1/16", I'd use that as a good litmus to identifying a "know-it-all", that doesn't know much. They'll likely be more of a pain in the ass than the profit from the knife justifies, even after you're finished with it. Maybe best to encourage them to look elsewhere.
 
stezann said:
I can't give measures, but you can have a thick backspring and an ok knife if you have thin liners/scales.
Personally i am not too much happy when a knife thickness starts to approach its height, one of the reasons i like single or 2 opposing blades models.
The benfit of having two blades in my opinion is that one of them can be very thin, for delicate tasks. Often a catch bit is included in the design, to allow for a difference in opposing blades thicknesses or to simply give more cleareance when you don't want asimmetrical grinds and same thicknesses.
Click to expand...

I tried a catch bit a while back and it came out awful. I have been just starting with 3/32 stock and plunge grinding all the way. It does kind of suck to grind over half the side off of a small blade though. And if you really look at it up close it is weird to have such a deep plunge, and sometimes the bolsters dont quite hide the steep plunge completely. I make mostly 2 blade patterns now. I will try the catch bit again, it is something i need to know i think. A little extra length on the master blade never hurts and i think it can be more elegant than having deep plunges. Maybe less warping issues too.

Ultimately i think javand is right and i probably wont ever make them happy. I will just keep making knives the way i want to i think.
 
Just wanted to thank stezann for suggesting catch bit. I had tried it, failed, and didnt want to try again. Now with more experience i can pull it off, and i believe i will make all my 2 blades this way now. Now i need to order more steel..

hnEgL4J.jpg
 
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