Storing autos

[ryanb]

I think I've seen pictures of autos in knife rolls in the open position. I would assume this is to keep the spring strong? It makes sense to me. Especially ones with kick springs that are not easily replaceable. Does this actually help?

[Bill DeShivs]

No, it doesn't. Springs don't get tired.

[wiseguy]

It can`t hurt

Does this actually help?

[Miller Bro's]

Springs don't get tired.

Sure they do

[Bill DeShivs]

No, they don't. They aren't alive. I have made thousands of springs. 4 have broken, from the same piece of stock.
Springs break because of work-hardening-think of bending a coat hanger until it breaks..
Properly made springs don't "get weak" unless they are about to break, or are flexed past their elastic limit.
Backsprings on slip joint folders are always under tension.

[Miller Bro's]

No, they don't. They aren't alive. I have made thousands of springs. 4 have broken, from the same piece of stock.
Springs break because of work-hardening-think of bending a coat hanger until it breaks..

Who is talking about breaking? The OP asked if the springs will get weak if compressed, (closed), I say they do. If you have ever worked in the auto repair industry you will see the difference with your own eyes, no different with a leaf spring or a coil spring on a car just a larger size compared to a knife spring.

How many autos have you worked on with a weak spring that will not fully open a knife blade? You say thousands why did the spring get weak? Did it come this way from the factory?

We could go round and round with this discussion and it has been done before on this and I am sure other web sites so I won`t go further with this thread but no matter what you believe like wiseguy said it can`t hurt to store the knife with the blade open.

[bestgear]

I'm not a metallurgy expert but I have been around vintage automobiles and all things mechanical for most of my almost 60 years. In my humble opinion, a properly hardened and tempered spring should not suffer any weakening or deformation when flexed within its design criteria and removing the load on a spring does not let it recover. That said, I rotate all of my loaded magazines every 90-days but mostly for inspection and cleaning purposes but I have never had a magazine spring fail. I would say that whatever method you prefer is the one to use and that there is no right way, just the way that's right for you.

[MITCH RAPP]

Here's My 2 Cents! Microtech Auto Knife instructions say it doesn't matter either way, can be stored opened or closed. It's really the opening and closing cycles that eventually Kills the Spring.

[orvet]

Properly made springs don't "get weak" unless they are about to break, or are flexed past their elastic limit.
Backsprings on slip joint folders are always under tension.

With all due respect, then why are there so many old switchblades with weak or broken springs?
The spring is installed in the knife and cannot travel beyond the set range of open to close, so how can they be flexed past their elastic limits? Were the springs just bad from the factory? If that is the case how do I know if the knife I’m going to buy has a good spring or a bad spring (whether buying a new or used knife)?

I grew up in the automotive industry and I have seen many old weak leaf and coil springs. Before the days of air and hydraulic suspension it was very common to change springs on cars & trucks. Aside from gross overloading, the travel of an automotive leaf spring is pretty much limited, like that of a switchblade or slip joint folder. Yet I have seen many weak (and broken) leaf springs in automobiles that were not abused. The spring action of a leaf spring and the shape of the leaf spring itself is very similar to the action of an old switchblade.

You said: “Properly made springs don't "get weak" unless they are about to break, or are flexed past their elastic limit.” I’m not sure I understand you properly, but that sounds to me like a properly made spring should never get weak. Do I understand you correctly?

If the properly made spring doesn’t get weak, then it stands to reason that it should not break. Is this correct?


You drew a parallel between switchblade springs in slip joint springs. You rightly point out that a slip joint spring is always under tension. However, the old-style switchblades springs, as opposed to the new style with the coil spring, are not under tension when they are open. I have worked on a lot of slip joint knives and yes; occasionally I do find one with a broken spring. But when I am in a flea market, garage sale, knife show or some other venue where I am looking at a lot of old knives, percentage wise I rarely find a slip joint with a broken spring. On the other hand it seems almost every other switchblade I pick up either has a broken spring or a weak spring. Can you please explain to me why this is? It would seem to me that it is part of the design, perhaps a design flaw in the old-style switchblades.

Thank you, I look forward to hearing your opinion on this matter.



Note: I do find a good number of slip joints that have weak snap or no snap. However when I examine or repair the knife I usually find that the round end of the blade tang has worn down and rounded off. There is no cam action left to the round end. The weak snap is not due to a weak spring but to a worn down blade tang.
When I replace the blade with a new blade that has a full round end then the knife snapped properly. Weak snap in a slip joint rarely means a weak spring.

[Bill DeShivs]

Wow!
Of course it can't hurt to store knives open. If the spring is going to break it will break upon closing.

"Weak springs"- Springs don't get weak. I'm going to assume you are generally speaking of American autos.
Older Schrade-type automatics did not have strong springs to begin with. Dirty pivots and dinged/crimped liners usually cause these knives to not fully open. Additionally corrosion of the spring can be a factor. Even stronger-sprung Italian and German knives are affected by the above. So, the springs aren't getting weak-the opening resistance is getting stronger. Many springs were bent by users to make the knives "open harder."
Much like your worn tang experience, this has been my experience with autos.

I have seen many 150 plus year old springs in both guns and knives that worked fine.

Springs will eventually work-harden and break from normal cycling. Otherwise, the spring should not weaken beyond an initial "set" upon the first cycle or two. How long it will take for the spring to fail has many variables, but number of cycles is at the top of the list. If the heat treatment of a spring is on the hard side, the life will be shorter. People like to play with switchblades.
Car springs (or any spring) when properly designed, made and heat treated do not weaken under normal use. The spring has to have been overheated, flexed beyond it's elastic limit, or have experienced shock or corrosion. Immediately before a work-hardened spring breaks, the spring will weaken considerably as it begins to break. Springs that are "bad" fail immediately within the first few cycles. Remember-the metallurgy is what it is, and it doesn't change with age, and the only variables are external-work hardening, over compression, corrosion, overheating, etc.
And yes, Miller Bros- I have literally made thousands of springs and worked on many thousands of autos.

[SamM]

This is the same debate I commonly heard about M16/M4 rifle magazines, that if you kept them loaded the spring would eventually weaken resulting in misfeeds. That isn't the case.

The weakened springs causing misfeeds were due to the constant cycle of being compressed and released. I have several magazines of my own I've kept loaded for a few years now, if anyone is interested in knowing if the springs have weakened or failed in that time, I'll dig them out, strip them down and report.

[Colonel26]

I don't know anything about auto knives. But being a gun nut the practice of storing an old gun cocked or decocked is often debated. A buddy of mine on a shotgun forum did a test with 1911 recoil springs. This guy works for the Air Force setting up and maintaining measurement equipment, so this stuff is right up his alley.

Basically, he took two springs, compressed one for a year in a jig, and left the other uncompressed. At the end of the year the compressed spring took a 1mm set. There was no other deformity and the spring flew across the room when the jig was released.

I have no dog in this fight. Just thought I'd share the information.

http://www.shotgunworld.com/bbs/viewtop ... 34&start=0

[zp4ja]

So I am a man of common sense which I use to make up for lack of knowledge at times and it has worked well for me so far. That said...

I think the point is here does an uncompressed spring last better as far as function and life expectancy than a spring that is compressed. I would venture to say yes. And by the way, the 150 year old auto and springs we are referring to I assume the person making that comment was not in possession of or witnessed effect on spring for that time period not do they know the history of the knife housing sad spring as far as being stored with spring compressed or not, IE knife stored open or closed, for whatever owners had it previously.

Sam, I too store many magazines loaded with no sign that I can tell yet but I do rotate and give them a rest every 3 months (and mark them as to date) just in case. Just not a debate I want to risk my life on if you know what I mean when it comes to possible FTF or failure to chamber. Worked well for me so far and of course, to each his own...

Weak sanp slipjoints happen for a variety of reasons I am sure and no mechanic here but I can say first hand, I have knives that had good snap and stored in half open or partial open (with no half stop rest) that did in fact weaken the spring of the knife.

It is "metal memory" not unlike the memory foam pillows and beds we all love. Just my opinion...

Jerry

[zp4ja]

I don't know anything about auto knives. But being a gun nut the practice of storing an old gun cocked or decocked is often debated. A buddy of mine on a shotgun forum did a test with 1911 recoil springs. This guy works for the Air Force setting up and maintaining measurement equipment, so this stuff is right up his alley.

Basically, he took two springs, compressed one for a year in a jig, and left the other uncompressed. At the end of the year the compressed spring took a 1mm set. There was no other deformity and the spring flew across the room when the jig was released.

I have no dog in this fight. Just thought I'd share the information.

http://www.shotgunworld.com/bbs/viewtop ... 34&start=0

Exactly Wade! Good point. Does the damn gun or knife still fire (rhetorical question)? Likely! Is the spring compromised or have "memory" as I sated, Likely! I think so!

Jerry

[orvet]

Interesting experiment though. The fellow who did the experiment said the spring was 1 mm shorter and also weaker than the uncompressed spring after sitting compressed for 1 year.

It seems to me that the same thing would happen to a switchblade:
The knife is made, spring compressed and boxed to sell. Lets assume it takes a year to sell the knife and the knife sits with the spring compressed; why wouldn't the switchblade spring be weaker like the pistol spring?

I am not trying to be argumentative Bill, I am just trying to understand what happens to the springs and why.
I appreciate you taking the time to explain.

[Bill DeShivs]

Perhaps he over-compressed the 1011 spring? 1mm in the overall length of a 1911 recoil spring is an insignificant amount.
If spring got weaker while compressed, every car would sit gradually lower. I personally have pistol magazines that have been constantly loaded for 35 years. They work fine. Lots of things have springs that under constant compression-if springs got weaker none of them would work.
All this is well proven fact. Allowing springs to "rest" offers no benefit.

[Colonel26]

Yes that was discussed in the thread. In other threads we speculated that after the initial set of the recoil spring there was no other change until some of the factors you mentioned caused the spring to fail. Like I said, I know nothing about auto knives. But I do know I have guns from the 20's, 30's, 40's, 70's up to 2015. They stay cocked with springs compressed and as far as I know they all have their original springs and still go bang every time.

[wazu013]

For my money the most important thing is to keep the spring oiled and clean. How it's stored is always up to discussion. I have a 70 year old pick lock that wants to jump out of my hand when fired. I'll bet it's been fired thousands of time and stored either way.
For the record I do store my autos open mainly because they display better

As far as the Tractor Trailer spring comparison, we used to have spring failure all the time. I've had pieces of them slide out on the road many times over 35 years in the business. I suspect if you drag your knife through road salt and temp changes for a few years and 300,000 miles open or closed it will fail.

[jw517]

I know nothing about cars but have trapped all my life. Trap springs,coil,long,jump,all weaken with use. Nobody,would store them set who cares about longevity. The quality of the spring steel matters a lot too. It’s not convenient to store all your knives open though. Hmmmm.

[No youre wrong]

This discussion always fails to mention the obvious things about storing a knife open or closed:

Tension on the liners and torquing them over time and tension on the sear and the springs that hold the sear in place

That all does get affected when keeping a knife closed.

So yes they should be stored open

[Bill DeShivs]

That tension does absolutely nothing until the parts move.
Metallurgy is a complicated subject that is above many people's heads.
Here's the simple man's answer:
If you NEVER close your switchblade, the spring can not break.

[Madmarco]

I don't think that no matter how many times you state this, Bill, everyone will EVER agree!

[jw517]

If one believes what others tell them then I have to say springs don’t lose their ability to store kinetic energy unless pushed past their designed limits. (Hyper extending). I guess I don’t know why traps get weak over time. I’ll agree with Bill. Maybe trap springs are not really “spring steel”?

[Madmarco]

Wouldn't traps be made of iron, jw, if that makes any difference at all.

[jw517]

Yes they are! Iron that was turned into steel.