All About Pocket Knives

I've noticed on most factory folders, that there's a crease running down the middle of the liner that keeps it from being perfectly flat. Does it have a specific purpose?
Some i've come across are really pronounced.
WB

WB,
I think it helps stiffen the liner.

What Joe said.

It increases the rigidity and helps stop any linear movement.... what Joe said.

..... Joe

It does serve to stiffen the liner, but I think also helps widen the mouth of the blade well enough so the blades don’t strike the edge of the liner as the knife wears and loosens up. It may be more important to have this on a single spring penknife pattern where the blades overlap and fit closely in the well, than it is on a camper pattern with a wider well and some shorter blades like can opener and caplifter.

I always thought that the crease was to give relief in the center to assure that the handles would fit tightly on the edges of the knife where they meet the liner .

Bob

Hmmm...that all makes sense. The only thing I could think of, was to insure that the handles touched at the edges. That seemed a bit silly. If you had 2 machined flat surfaces, you wouldn't need the crease.
I see now, that with the crease, the handles don't have to bear the brunt of the stress in the center of the knife. Also, now that Dale mentions it, on this Robeson toothpick i'm working on, the crease does seem to have the effect of funneling the well opening a bit.
Reckon I should've known the factories would have a good reason and that you fellers would know why. It's clear as a bell now that the words have been written. Thanks guys!
WB

P.S. I won't peen the crease out then.

P.S.S. What Bob said!

robinetn wrote:I always thought that the crease was to give relief in the center to assure that the handles would fit tightly on the edges of the knife where they meet the liner .

Bob

This is the reason for the crease.

IM

I'm thinkin', pretty much all of the above.