Just had an epiphany! I now realize why slip joints have such nicely shaped blades.

[Macchina]

I never thought about why slip joints can have long narrow blades that are ground thin and streamlined while one-hand opening knives tend to have clunky blades with lots of steel behind the edge. It's all about the momentum the one-hand opener needs to carry itself to the locked position. If the blade of a one-hand opener does not have some mass to it, it won't be easy to overcome the friction of the lock and swing all the way open. Slip joints are not held to this requirement, so blades shaped like anything the Elephant's toenail to the Toothpick are possible. I am really starting to dig carrying around and using just a Trapper or a SAK lately. That streamlined narrow blade shape has a lot to do with it. I think something weird is happening to me...

 

[stabman]

Not really, as not all (or most) one-hand openers are set to swing the rest of the way with inertia.
I prefer knives where I must provide the opening force through the whole range of motion; for one thing, this keeps me from getting nailed with a prohibited weapons charge (gravity/flick knife).
Plus, there ARE very slim bladed one-hand openers as well.

 

[shecky]

It's all about the momentum the one-hand opener needs to carry itself to the locked position. If the blade of a one-hand opener does not have some mass to it, it won't be easy to overcome the friction of the lock and swing all the way open.

This really only applies to knives that are "flickable". And even then, only somewhat. One hand openers can and do come in a variety of shapes. Thumb studs can be used on just about any shape. Opening holes typically need a certain amount of blade width. Assisted openers can have very thin and narrow blades.

Thick, girthy blades are popular because knife buyers simply like them. Especially in the market that serves one hand opening tactical-ish trust-your-life-to-this-knife mentality. I tend to simplify this frame of mind as simply "macho". Bowie geometry is simply more appealing to more folks than paring knife geometry, even if the paring knife is a vastly more usable blade. A big, fat blade simply screams "badass". It also tends to add perceived value and workmanship. And thus justify higher cost.

But yes, slipjoints are not very limited in the shape or thickness of blades.

 

[messer454]

Bowie geometry is simply more appealing to more folks than paring knife geometry, even if the paring knife is a vastly more usable blade.

I think this is why. AG Russell talks a little bit about this when discussing his thin deer hunter fixed blade. I think the "market" just wanted thicker and thicker knives. Now anything thin is considered weak. As far as one hand opener specifically...the newer Spyderco Delica full flat ground is a nice thin slicer!

 

[dalee100]

Hi,

Having your slip-joint fit your pocket well, rather than hang from a clip is also a factor in thin blades and general profiles. And as has been mentioned, thin blades slice better than thick.

But I wonder if the fact that historically high carbon tool steels weren't cheap nor always easy to get also played a part. So using as little as possible was desirable. Particularly if you wanted to make an affordable piece of cutlery for the masses to buy. And reducing the thickness is pretty effective at doing this.

Dale

 

[knarfeng]

I never thought about why slip joints can have long narrow blades that are ground thin and streamlined while one-hand opening knives tend to have clunky blades with lots of steel behind the edge. It's all about the momentum the one-hand opener needs to carry itself to the locked position. If the blade of a one-hand opener does not have some mass to it, it won't be easy to overcome the friction of the lock and swing all the way open. Slip joints are not held to this requirement, so blades shaped like anything the Elephant's toenail to the Toothpick are possible. I am really starting to dig carrying around and using just a Trapper or a SAK lately. That streamlined narrow blade shape has a lot to do with it. I think something weird is happening to me...

I think this is why. AG Russell talks a little bit about this when discussing his thin deer hunter fixed blade. I think the "market" just wanted thicker and thicker knives. Now anything thin is considered weak. As far as one hand opener specifically...the newer Spyderco Delica full flat ground is a nice thin slicer!

One need only look at most Al Mar designs to understand that the OP's premise is incorrect. His blades are one-hand openers, but have thin, almost traditional, shaped blades.

A scan of the posts in General and how many of them ask about "tough" knives will confirm Messer's hypothesis.