Spring weakening with prolonged compression...

[Docv400]

I personally think it's a total myth.

To prove/disprove it I've just made up a simple spring loading rig, basically a length of 2X3 with a hole in it that can be held in a vice.

Through the hole (vertically) goes a length of 8mm studding with nut and washer at both ends.

Put the spring between the top washer and the wood, and hang a weight on the bottom.

Measure the 'free' (uncompressed) length and the compressed length, then fully compress the spring on the studding by winding the nuts up.

Set aside and leave for a period of time.

Then re-check the compressed length with the same weight.

If it's the same, as I think it will be, then it's proved to be a myth.

 

I've done two springs;

Spring 1. Systema M130

27 coils of 1.6mm wire.

Free length 174.

Weighted length 137mm

 

Spring 2. Marui standard

25 coils of 1.3mm wire

Free length 152mm

Weighted length 54mm

 

Any suggestions/requests how long I should leave them?

A month, two, or more?

[MDK_Marshal]

A month or two should be fine. IMHO, the best bet is to wander off and just forget about it for a while

[ED-SKaR]

SCIENCE!

 

 

Seriously though, its good that someone has the good sence to do a properly fair test to determin things that are fairly important, but nobody has anything like remotly accurate ideas.

 

 

I await results and findings.

[Docv400]

I think it's a fair test, although some believe (me included) that possibly only very poor quality springs could suffer the (alleged) problem, if any do.

I have a cheap and nasty MP40 springer I bought before I got into Airsoft, I could whip the spring out of that and try it.

Might be quite fitting to get to the spring by obliterating the rest of the gun with the AGM MP40 I have here at the moment

 

A month or two should be fine. IMHO, the best bet is to wander off and just forget about it for a while

Oh, I'm quite good at that .

Shall we say, Sat 20th June?

I've set a reminder on my mobile.

[snorkelman]

leave em a month or two that should satisfy the believers

 

but couple of suggestions - not going to have a material impact on what you're testing but just to head off any off the inevitable you didnt compress them enough, you're weights arent heavy enough the systema spring would compress more than that in a gearbox etc

 

find weights that compress each by the same amount as a full piston stroke would

 

then run the nuts up on them to hold them at that length

 

that should mimic the max compression anyones going to be able to apply with them sat compressed within a mechbox

 

at end of the two months measure their free length for any changes, and the amount of load now required to compress them to that 'full piston stroked' length again.

[thewallhitme]

well, i do know that a new spring will "bed in" and reduce fps by a little, but the real question is, will it reduce significantly after that? my guess is no.

[bjorn]

I have evidence of a Systema PSG-1 300% spring being compressed for like umm, 3 years in a row at least, after which it shot a mere 125m/s. A brand new Systema M160 spring in the same gun started shooting 155m/s after spring swap.

 

B.

[Docv400]

leave em a month or two that should satisfy the believers

 

but couple of suggestions - not going to have a material impact on what you're testing but just to head off any off the inevitable you didnt compress them enough, you're weights arent heavy enough the systema spring would compress more than that in a gearbox etc

find weights that compress each by the same amount as a full piston stroke would

then run the nuts up on them to hold them at that length

that should mimic the max compression anyones going to be able to apply with them sat compressed within a mechbox

at end of the two months measure their free length for any changes, and the amount of load now required to compress them to that 'full piston stroked' length again.

I used the same weight to compress them both so I can repeat the test exactly at the end of the period.

I've wound them up so that they are both virtually coilbound (all the coils touching), so more than they would be in any AEG.

If they don't lose any strength with that, they certainly won't in an AEG.

 

 

I have evidence of a Systema PSG-1 300% spring being compressed for like umm, 3 years in a row at least, after which it shot a mere 125m/s. A brand new Systema M160 spring in the same gun started shooting 155m/s after spring swap.

B.

I've heard similar claims before, and I don't dispute what you (or others) experienced.

 

However, if you stick any Airsoft gun away for an extended period, the piston-head and cylinder-head o-rings, and the hop rubber, will 'dry out' and shrink slightly, and lose their ability to seal well.

Plus you'll get dust accumulating inside the inner barrel and possibly the cylinder.

All of which will lead to a reduction in FPS.

As for the 'improvement' noticed with the replacement spring?

I'll wager that whoever rebuilt the gearbox after the spring swap re-lubed everything nicely before testing it .

[bjorn]

Actually I took the compressed spring OUT OF THE PSG-1 and then put it in an A&K SR-25. Since we did not get satisfying results we decided to try the M160 spring which gave what was looked for.

 

So same system, nothing was changed expect the spring. A few weeks later the M160 still shoots same.

 

B.

[Danke]

I"ve heard both ends of this. One that it is the cycling of the spring that causes it to loose it's temper and take a weaker set. Two that being held under load will sack out a spring. I do unload my mags, and back off my torque wrench at the end of the day.

 

I'd say try this with a bit of a smaller weaker spring, like a magazine one.

[Yuri]

Like Doc said, there are so many parts in an airsoft gun that any drop in fps could be atributed to lot of things. The only way to get real data is to remove all other variables and isolate the spring.

 

Make sure you don't use brand new springs. This way any 'breaking in' will not affect the experiment.

 

[Hammerfall]

I've never really thought about isolating the spring and seeing if it is fact or myth. From my limited engineering knowledge i think it be myth, but i'll be happily proved wrong.

 

Slight digression, but in my 5 years of playing airsoft only once have i heard of a spring actually snapping in a gun. Has anyone else heard of this?

[The General]

Heat causes steel to lose its temper. Not the action of movement unless its causing huge friction and thus heat.

 

The kind of heat needed to cause a steel spring to lose temper would melt the rest of the gun.

 

Low quality steel and poor tempered steel would result in a loss of compressive strength until it reached its set point.

 

Otherwise, its the result of other parts settling or bedding in. Its normally noted in new guns that they settle FPS wise after a few thousand rounds.

 

A well made spring from good steel with a good temper would not noticably change in years with little use, compressed or otherwise. The important part being "with little use"

 

The other important issue being how good are the springs in our guns? How consistant?

[Tom Andrews]

I've never really thought about isolating the spring and seeing if it is fact or myth. From my limited engineering knowledge i think it be myth, but i'll be happily proved wrong.

 

Slight digression, but in my 5 years of playing airsoft only once have i heard of a spring actually snapping in a gun. Has anyone else heard of this?

 

Yes, I've changed quite a few springs (at least five) due to physical breakage over the years, some had broken in several places. Of course you have to wonder what punishment the springs took to break in several places, I suspect continuing to use the gun despite it making a horrible noise.

 

To the best of my recollection none of the springs were Marui, at least two were Systema and one from a JG.

 

Its possible that penny pinching or poor quality control of the manufacture of the basic wire was the cause rather than failures of the actual spring manufacture.

[Yuri]

Slight digression, but in my 5 years of playing airsoft only once have i heard of a spring actually snapping in a gun. Has anyone else heard of this?

 

I've had a Systema spring snap in two. It lasted four years so it had a good run.

[MDK_Marshal]

Systema and element springs have snapped on me, or people who's guns i've fixed, over the past few years.

 

Think it totals up to three or four now. Only one was an element spring, too...

 

I've said it many times before; systema stuff is WAY overrated, and DEFINITELY overpriced!

[Delfi]

Rather than using weights etc for this test would it not be a better idea to use a long bolt with a washer and nut at one end?

 

Put the spring on the bolt and tighten the nut down on the washer to a desired compression length.

 

D

[Kiki-Jiki]

Very cool idea. Though do you think you could do it with a few other brands of springs? I've heard PDI springs are pretty good at keeping their strength over time, but that's just kind of a myth (until somebody proves it), so I think it'd be cool to test a PDI spring.

[Docv400]

Slight digression, but in my 5 years of playing airsoft only once have i heard of a spring actually snapping in a gun. Has anyone else heard of this?

I've had two AEGs in with snapped springs, both close to the end (2 or 3 coils from end)

 

Rather than using weights etc for this test would it not be a better idea to use a long bolt with a washer and nut at one end?

Put the spring on the bolt and tighten the nut down on the washer to a desired compression length.

D

Read the description again Delfi

Put the spring between the top washer and the wood, and hang a weight on the bottom.

Measure the 'free' (uncompressed) length and the compressed length, then fully compress the spring on the studding by winding the nuts up.

Set aside and leave for a period of time.

Hanging the weight on the spring is to get a datum for the spring's strength.

It's not an actual rating (e.g. lb-in or kg-mm), just a datum.

If it loses stength, it'll compress further with the same weight when I retest it after the two months.

 

As for testing a PDI spring, if someone wants to send me one...?

[Delfi]

Read the description again Delfi

 

Ah right ... I see where you're coming from now

 

I have a some springs here that you would be welcome to have for testing if you like. They're mostly JG and CYMA (strong 380+ fps).

 

They're ACM so the quality (or lack) of the wire used may be suspect and as a consequence they may be more susceptible to power loss through prolonged compression.

 

Cheers,

 

D

[Docv400]

Well if you're happy to pay the postage, PM/E-mail me.

[Gigueand]

Sorry to necro this thread, but did anything ever come of this? Was the experiment ever conducted and, if so, what were the results?

[Docv400]

Like I said, I'm good at forgetting things for a while.

I'll get them down from their resting place this week and measure them up.

I did think about them a couple of days ago actually, I was using the 4-jaw chuck, that I used as the weight, to make some .22 blank adaptors for BFGs.

[maxxxmonster]

i say they would have lost at least maybe some of their tensile strength.

[Gigueand]

Sorry to (once again) necro this thread, but what was the verdict on this?