Can displaying folding knives long-term half-open affect them?

I

IndyF1

Joined
Jul 19, 2022
Messages
2
I have a collection of mint folding pocket knives that I keep permanently in a display case. The blades are all partially open. I wonder if this might put some stress on the various metal components and warp them over time in that unusual position. Should I display the knives closed or all the way open?

I thought of that problem because I have an Old Timer with a liner lock that I carried for several decades. One day, the liner stopped springing out enough to lock the blade. I don't know why it happened and could only guess that it just wore out over time and lost its "springyness."
 
No experience and not an engineer. Can only guess it MIGHT depend on the material composition of the spring and MAYBE other properties which vary from knife to knife depending on manufacturer.
That said, I THINK you should be okay so long as only one(1) blade is partially open on each spring. Multiple (more than one) blades partially open on the SAME spring ... is not good.
EDIT: One thing that comes to mind are collector issues that come in display boxes etc, that are packaged with blades partially open. There are not ever any instructions to close the blades for long term storage
 
If you're talking about modern knives, I don't think you'll hurt them by displaying them with the blade partially open. Now of course unexpected things can happen, we've all heard stories about backsprings breaking on knives stored closed in a drawer. There have been knives that remained thumbnail busters for twenty years of daily use, others that have become gravity knives.

I photograph my knives with all the blades posed. I know that there are people who think that even a few minutes at maximum spring flex is a recipe for disaster. I'm not one of them.

I wouldn't display old knives partially opened. How old? Danged if I know... :cool:
 
I’ve read that you can soften an overly tough back spring by leaving it half open, so I’d guess yes. But if it has half stops it might not matter if the half stop is the same distance from the pin as it is closed.
 
  • Like
Reactions: JM2
brownshoe said:
I loosened up a Queen by leaving it part open. A couple of years. Didn't change much but enough.
Click to expand...
I tried that on an older GEC 73 nail breaker..... Left it partially open for 3 months and didn't do a thing. Eventually, just learned how to open it differently.

Personally, I wouldn't leave a knife partially open for years and years unless it was at half stop, but I have no idea what would happen. I just wouldn't want to risk it.
 
Yes. It can adversely affect the backspring(s) depending on the design of the knife.
If there are two blades on one spring, never open both half way at the same time. Doing so is asking for a broken spring. To display both blades, fully open one, then the other half way.
Only If the blades have a halfstop  and the back spring is flush or slightly sunken at the halfstop position is it "safe" to open both halfway.

Note there are no guarantees.
I am not the only one who's had a knife in storage or on display with the blade closed to suffer a broken backspring on that knife between the time it was put up and taken down. ☹️
 
If the spring is stressed it can reduce the pull a little over time. I’ve left a blade about 1/3 open for extended periods to soften the pull. Does not always work, but sometimes. You see a similar relaxation on torqued/tensioned bolts.

I doubt a knife open to the half stop would experience any change. The stress on the spring would be very low. Not impossible but unlikely.
 
Properly designed springs should not fail if left in any normal range of their operating positions. What wears springs is repeated compression and decompression, and flexing beyond the design parameters. Of course, not all springs are made properly, and imperfections can also occur. I would not leave a collectable slipjoint in a half open position, for the off chance that the spring isn't within design parameters.
 
As mentioned, if the spring is ideally heat-treated & tempered, it shouldn't change much over time if left partially open, UNLESS it's been stressed beyond it's tolerable travel (also mentioned previously).

The one thing that discouraged me the most, about folding knives with blades left partially open, was getting 1/4" ovals of skin sliced off the ends of two fingers when one of those partially-open blades snapped shut while I was handling it. It was a brand new knife, just purchased and shipped to me in a display tin with three blades partially open. The blade snapped shut as I attempted to extract it from the molded insert in the tin. Bled like crazy for awhile and stung like heck, too. It was a 5-blade Case Sowbelly - and the blade snapping shut was at one end of the spring, with the blade at the other end of the same spring also partially open. So, A LOT of spring-tensioned snap on that one, when it closed on my fingers. It was the smaller clip blade seen in the photo below of that knife.
uiAju1S.jpg
 
they have this debate for automatic knives as well, im happy to read the opinions
 
Obsessed with Edges said:
As mentioned, if the spring is ideally heat-treated & tempered, it shouldn't change much over time if left partially open, UNLESS it's been stressed beyond it's tolerable travel (also mentioned previously).

The one thing that discouraged me the most, about folding knives with blades left partially open, was getting 1/4" ovals of skin sliced off the ends of two fingers when one of those partially-open blades snapped shut while I was handling it. It was a brand new knife, just purchased and shipped to me in a display tin with three blades partially open. The blade snapped shut as I attempted to extract it from the molded insert in the tin. Bled like crazy for awhile and stung like heck, too. It was a 5-blade Case Sowbelly - and the blade snapping shut was at one end of the spring, with the blade at the other end of the same spring also partially open. So, A LOT of spring-tensioned snap on that one, when it closed on my fingers. It was the smaller clip blade seen in the photo below of that knife.
uiAju1S.jpg
Click to expand...
Wow that sucks. Sorry to hear of that. I’ve had similar wounds but not from a knife closing on me, so I know how it burns. I had a piece of tin roofing slice through my leather glove and take a round slice out of my fingertip once. It turned a big man into a wuss real quick.

To address the OP, well, every case display I ever saw had the knives open partially for display.
 
JM2 said:
Wow that sucks. Sorry to hear of that. I’ve had similar wounds but not from a knife closing on me, so I know how it burns. I had a piece of tin roofing slice through my leather glove and take a round slice out of my fingertip once. It turned a big man into a wuss real quick.

To address the OP, well, every case display I ever saw had the knives open partially for display.
Click to expand...
Some vivid and interesting memories around that event. It was part painful, part embarassing and a little bit comical in retrospect. I'd picked up that knife in a package at the Post Office and brought it home. Had plans to meet a friend for a steak dinner that evening. So, after getting home, I opened it up and immediately got bitten by it. I vividly remember dropping the knife at the pain and watching one of the skin slices from my fingertip sort of flutter in snowflake-like fashion to floor, following the knife as it dropped.

Still went to dinner with my friend that evening. Trying to cut my steak on the plate, in a crowded restaurant, with blood-stained Band-Aids on two fingers handling the steak knife was both the comical and embarassing part of that whole event. But it was still a good dinner with a very good friend, and a memorable lesson learned. :)
 
Many have already mentioned this, but wanted to elaborate a bit.

Maybe it is somewhat different from structural steels but steels, in general, exhibit similar stress/strain behavior, having an elastic range and then, 'beyond.' In structural steels, there are definitive yield stress points and plastic curve beyond it. For springs, yield stress is defined a bit different but similar concept regardless. The spring is suppose to work within the elastic range and as long as it is not pushed beyond the yield stress, the form will retain it's shape indefinitely. Given this, unless the back spring is bent close to or beyond yield, I can't imagine any adverse changes.

I grabbed the below stress/strain curve off of Google (doesn't really matter as properties of steel are 'mostly' very similar). Most importantly, it is the straight ramping part in the beginning of the graph that relates to this post. It shows that the steel deforms as stress increases but comes back to 0 when the stress is released. As it is pushed beyond the straight portion of the curve, the metal doesn't 'spring' back...

1658328124597.png

HOWEVER! We've all seen posts with broken back springs here, but those are posts regardless of whether blades were open or not and in some cases just sitting in a box somewhere. I'm guessing this is a defect of the material from the factory, such as moisture or differing particles in the batch...just a guess.
 
I have both of these knives. Remington Mini Trappers manufactured in 1991 and stored as shown in the last picture since they were make.

1658331287251.png
1658331329859.png
1658331395067.png

Both knives have "half stops" and the Muskrat Blade on both knives is snappy, solid, firm, on both knives; however, the Spey Blade on both knnives while still having plenty of snap is somewhat soft both opening and closing. I believe that is because the knives were stored for 30-years with the Spey Blade partially opened as shown placing some strain on the springs. Both knives are perfect users and I carry both regularly with great satisfaction.

This Remington Mini Trapper made in 1983 came in a box as shown with both blades fully closed. Both blades have crocodile snap blades even after 38-years in the box.

1658331966013.png

I think we have to consider that some say one of the remedies for overly strong springs (hard pull) is to leave the particular blade effected half open to weaken the spring/pull.

Hopefully this post has made some sense.
 
Last edited:
I will never forget the look on Stan Shaw's face when Duncan politely suggested it might not be best to open two opposing blades on a spring at the same time! :eek: 😂 :thumbsup:
 
You must log in or register to reply here.
Back
Top