Should Speedsafes be stored open or closed?

J

James Y

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Feb 18, 1999
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I have heard that regular automatics should be stored open to avoid weakening the tension, etc., of the opening spring. Is the same true with the Speedsafe and other "semi-automatics"? (I know the Speedsafe is not technically an automatic, but wondering if the torsion spring (bar??) is subject to the same potential problems).
Jim
 
Seems like a good time for a newbie to jump in and reply...

I know from firearms experience that it is the repetitive cycling of a spring that causes it to weaken and/or fail, not the constant load that is placed on them. A firearm magazine can stay loaded for years, and still function properly. Mag springs wear out when they are used (compressed and decompressed) repeatedly.

I would assume the same thing is true of any coil or torsion springs in a knife. There should be no damage if left under tension.
 
Originally posted by James Y
I have heard that regular automatics should be stored open to avoid weakening the tension, etc., of the opening spring. Is the same true with the Speedsafe and other "semi-automatics"? (I know the Speedsafe is not technically an automatic, but wondering if the torsion spring (bar??) is subject to the same potential problems).
Jim
Click to expand...

Jim, that's a very good question. There is an article regarding the storage of autos in the current issue of Tactical Knives. The writer suggests that autos should be stored in the open position, however, I don't know how the tension on Kershaw's torsion bars affect the knives when closed for a long period of time. I would have to ask, does it depend on how long the knife is to be stored? For instance, a retailer may have an auto or a Speed Safe knife stored in it's original package for months before it is sold. Perhaps Ken himself can jump in and offer some advice?
 
I think maybe the man best suited to answer this question is the man who designed it!

Are you out there Ken?
 
Originally posted by shane45-1911
Seems like a good time for a newbie to jump in and reply...

I know from firearms experience that it is the repetitive cycling of a spring that causes it to weaken and/or fail, not the constant load that is placed on them. A firearm magazine can stay loaded for years, and still function properly. Mag springs wear out when they are used (compressed and decompressed) repeatedly.

I would assume the same thing is true of any coil or torsion springs in a knife. There should be no damage if left under tension.
Click to expand...

I'm going to have to disagree with you.
Springs wear out both from constant stress and from repetetive cycling. There are names for both kinds of wear that the spring experiences. Constant stress will cause a spring to "fatigue" which means it loses its ability to extend its full length as it once could. I forget what the name is for the stress it undergoes from repetetive use.

If you think that a magazine can stay loaded for years and not suffer you are quite wrong. If you are doing this then you are not treating your firearms well. There are many people out there who "download" their magazines. They keep one or two less than the full capacity in them which greatly increases the life of the spring. I don't personally do this but I check my springs often on my Glocks and my Mossberg.

As to the speed safe knives: I would store them open just to be safe.
 
ThinkOfTheChildren is right, up to a point.

Trying not to "fatigue" you with engineering jargon, I only need to point out that a very important factor is the Elongation of the spring, or, in simple terms, "the percentage of travel that you have used up".

Let's say that we have a magazine spring with a "free" lenght of 20cm that can be compressed up to 3cm before it is "coilbound". So, 20-3=17cm total "possible" spring travel.

When you load the magazine to its full capacity, you almost use up the entire spring travel, but when you only load one or two cartridges, the spring only measures e.g. 16cm (2cm already tensioned when assembling the magazine, another 2 from the two rounds), so you have transferred the "zero point" only 4cm from the possible 17cm, loading the spring much less than full capacity. This has a very large effect on spring fatigue (which is almost negligible with 2 rounds, as opposed to a full magazine).

In conclusion: with a "speed-safe" knife, it seems that the percentage of spring travel from the open to the closed position is very small as opposed to the total possible travel of the spring, so there should be absolutely no problem storing the knife closed. Remember: we measure the total possible travel of the spring OUTSIDE of the confines of the mechanism of the knife: from the "free" position of the spring to the point that the spring is "coilbound" or it "fails" (breaks or bends) in the case of torsion bar springs.
 
Originally posted by ThinkOfTheChildren


I'm going to have to disagree with you.
Click to expand...

No need to disagree with me! Disagree with Mr. Wolff who makes the springs that are probably in your Glock right now! Maybe firearm springs are different than knife springs, and I should stick to what I know?

www.gunsprings.com

By the way, I don't advocate keeping tension on a spring for years - I change my mag springs once a year, regardless if they have sat, or been used. :)
 
I asked this exact question a couple months ago ("Storage of Onions") and the consensus at the time seemed to be that the mechanism is not under significantly greater stress closed than open. However, it would still be interesting to hear from the man himself.
 
Shane45-1911,

This is from the site you linked me to:
5. Should I unload my magazines, rotate magazines, load with fewer than the maximum rounds? How often should I change magazine springs?

Magazine springs in semi-auto pistols are one of the most critical springs and the subject of much debate and concern. Magazines which are kept fully loaded for long periods of time, such as law enforcement applications, will generally be subject to more fatigue than the weekend shooter's magazine springs which are loaded up only when shooting. Magazine design and capacity also affect the longevity of the spring. Older designs where maximum capacity was not the goal such as the 7 round 1911 Colt magazines will last for years fully loaded. There was a lot of room for a lot of spring which reduced the overall stress on the spring. In recent hi-capacity magazines, the magazines were designed to hold more rounds with less spring material. This puts more stress on the spring and will cause fatigue at a faster rate. Unloading these magazines a round or two will help the life of the spring. Rotating fully loaded magazines will also help the problem somewhat but is not always practical. In applications where the magazine must be kept loaded, a high quality magazine spring such as Wolff extra power magazine springs, will provide maximum life. Regular shooting will verify reliability and regular replacement of magazine springs will provide the best defense against failure from weak magazine springs.
Click to expand...

So mr. Wolff is saying what I'm saying. He is just making the point that there is not much of a problem in 1911 single stack mags. He even makes the reference to downloading that I was talking about and specifically mentions spring fatigue. I don't see how the site disagrees with what I said above.
 
My first reply to this Question

After taking this blade apart I know the answer.

The torsion bar is an L shaped, basically, piece of ?spring steel.

Now, with the knife open there is NO load on the spring.
This is a statement of fact! In that first post I misspoke and was far from precise in my statement, sorry.

As for the knife in the closed position, the bar HAS a load on it.
Without taking measurements, in other words, it's my opinion, the spring is under 90% of its total load.

Opening the knife using the flipper is fairly easy, so before that magic point, when the blade opens, the load on the spring increases the remaining 10% to its full monty...er.. load.

peace!
 
Thanks for all the replies!
This has created some very interesting discussion, to say the very least. Looks like I'll have to find a clear, safe place to store my (only 2) Speedsafes open! :)
Jim
 
I have no personal knowledge of which storage condition is better, but over on the Knifeforums General Discussion Forum, Tom Mayo says that the mechanism is under the same stress closed as open.
 
Yeah, but what does Tom Mayo know! ;) Just 'cause he hangs out at Ken's shop whenever he feel like it, he thinks he knows sometime about knives ;). j/k

Actually I've taken apart my Random Task, and when it is in the OPEN position the torsion bar has no load/tension; when it is in the CLOSED position there is some tension, but I have no real idea how much tension. In any case, I store my knives closed, because I think it'd be pretty unsafe to have open knives lying around in a drawer. :eek: Plus, if it's a Kershaw knife, they'll replace it if it fails. If it's one of Ken's custom knvies he'll replace it if it fails.

I would tend to agree that cycling the knife would cause more wear on the torsion bar than having it sit in a case/drawer open or closed. A friend cycled his knife about 50-100 times per day, and after about a year the torsion bar broke. Kershaw fixed it, no problem.

~Mitch
 
Many materials when under constant stress "creep". That is they permanently deform or take a set. Wood and concrete are good examples of this. Wood will deform just under its own weight. This all takes place in the elastic stress range. So short duration loads that are not constant do not affect the material if the material is in its elastic range. Creep does not effect the stess capacity of the material like fatigue.

Fatigue is the wearing out of the material in the elastic range causes by repeated cycling load unload of changing stess. The higher stresses tending to lead to shorter life. Stresses need to be high to really shorten the life of the spring.

To my knowlege steel does not creep so I store my Mini-Task closed.
 
My own personal opinion is to store the Onions in a cool dry place and to chuck them out if you start to see stalks growing. :D j/k

Actually, steel can creep.

Steel will not creep when subjected to repeated cyclic loading. It will fatigue. Fatigue is what happens when the micro-structure of the steel (atomic bonding and/or crystalline joints) breaks down after repeated cyclic loading. Fatigue can cause the steel to break even if there is no associated creep.

Creep occurs when the steel is subjected to a static load that is within a certain percentage of the maximum yield stress of that type of steel. This percentage is lowered when the component is subjected to cyclic loading or elevated temperatures.

Why do we associate creep with cyclic loading? Because, quite often, there is a certain amount of static load included in the cyclic load. This is almost unavoidable in many of the applications we subject steel to.

Why do we not see steel structures around us creeping? This is not a simple subject and I will only be touching the tip of the reasons.

The stress required is quite high for immediately visible creep, or the length of time required is quite great (decades). Sufficient stress to cause 10% strain will result in a permanent deformation for most steels, but you can see that steels will strain (elongate) under even low tension. However, this elongation (the amount of stress required to create it and the amount of resultant strain) is also highly dependent on the ductility of the metal. Most structures are designed to never go close to the 10% limit for safety reasons. Even then, the cyclic loading it is subjected to will promote creep. We still are unable to see it because it happens in small increments over long periods of time. Objective measurements over extended time frames are needed to expose this.


Not sure if all that helped any, but my own personal take on storage of spring-assisted-opening devices is to store them in the opened or semi-opened position, whichever places the least amount of force on the spring/torsion bar.
 
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