Can pellets be too heavy for a springer?

[phoebeisis]

Sorry about the detour-but valve springs-undergo perhaps 1 BILLION cycles-and now a days RARELY break.
From what I have read the reason air guns springs- break-
in what would seem to be a MUCH MILDER environment( valve springs are violently "cocked" many many times per second-
But the claim is the Air gun springs break because they are compressed to ALMOST full compression-
Guessing you have to UNWIND THE WIRE-
say 40 coils- 25mm=80mm  circumference per coil- each 80mm coil in a 80mm stroke gun-bent 2mm  for 80mm 1mm per 40mm(oh-I was unclear-just uncoiling one coil-circumference)
a carspring-maybe 35MM=110mm circumference each-perhaps 15 coils??  7.5mm "stroke" so perhaps .5mm per 110mm length- 1mm per 220mm
so the explanation-the air gun springs are BENT MORE- yeah looks like MUCH more 5x as much 220/40=5.5x as much
Looks crude guess like air gun springs are bent 5 times as much as car/motorcycle valve springs-
so makes sense-they break
but like Mike Bulldog says-not so clear WHY heavy pellets are more likely to break the SPRING

On the other hand-as Mike will confirm-CAR/PLANE/MOTORCYCLE valve spring DID break when  high performance folks went to BIGGER/HEAVIER VALVES- it was a HUGE problem-
AND it is the original WHY of 4 valve heads instead of 2 valve heads
It wasn't to increase flow-it was because the heavier BIG valves BROKE the valve springs-
as Mikes Kawa -and harley-and GM/CHEVY pushrod V-8 clear demonstrate-you can flow PLENTY of air thru 1 big hole

So there IS  car/mc engine indications that HEAVY  is tricky
Saying that I STILL am not clear why a 18 grain 22 would be worse than the 13 grain-since the SPRING is THE SAME SPRING- same wire same compression-same everything
WITH the heavy pellet-the spring should  slam forward-more slowly??
So I still dont see WHY the heavy pellet is harder-same compression  same thickness of wire-
only difference is how it slams forward-and seems like it would slam forward MORE SLOWLY??

Hector says heavy does break springs-but still not clear WHY
I believe him- he is very experienced- but WHY?
PS The numbers-on the springs-guesses-made up numbers off top of head-but they are ballpark-and 5 times the bending-clearly shows why the air gun springs break-

[Underdog]

Why would a beehive spring be better? And what IS a beehive spring anyway?

[HectorMedina]

Interesting, I have a 177 pro compact. I shot, exclusively, JSB 10.3 gr pellets. They were, by far, the most accurate in my rifle.

I only got about 2000 rounds on the factory spring. I took it out to shoot after it had been sitting idle for several months. The first shot sounded horably wrong so I stopped immediately. On inspection, my spring was broken in two places. Very odd to me! My question is, if heavy pellets can cause abnormal spring wear via bounce/vacuum, wouldn't this be a perpetual problem for the same rifle in .22 caliber since it would have the same spring, piston, and tube but would always be pushing more weight?

Here is a pic of original spring next to vortek replacement.

Very odd to you, but not to me, T Higgs.

This is EXACTLY what the mathematical models predict.

The two places where there are most collisions between coils when using a loose guide are the beginning and the end. A collision is not the problem, the problem is that when a spring collides with its neighbour coil, it means that while one coil is compressing, the other is decompressing. It is these SWINGS in the DIRECTION of the stress that fatigue the metal much faster than the simple valve operation of motor engines.
When the same gun operates in 0.22" cal. it operates at a much slower rate (the lower MV comes from a slower cycle all over), this reduces the overall bounceback energy, as the expansion ratio of the barrel is greater and the backpressure, therefore, is lower.

The fact that your gun was a compact then tells us that collisions still exist at that barrel length in that caliber, in other words, the 34 Compact is not compact enough in 0.177" cal.

Nice stock, BTW! Congrats!

[HectorMedina]

Sorry about getting sidetrack with bikes.

Back to heavy pellets in spring guns, but also related to engines since they also use springs to open and close valves. I am somewhat baffled and perplexed how the weight of the pellet has any real impact on the life of a spring and how leaving one cocked for long term degrades the spring by significant amounts.

The spring does not know what weight pellet is in the barrel since it will expand at a given rate allowed by its wire diameter and ID/OD and number of coils and amount of compression when cocked. As T-Higgs stated there are many spring guns that use the same spring, piston, guides and so on for 177, 22, 25 calibers in which you a wide variance in pellet weights per caliber of gun.

In relation a motor vehicle engine uses coil springs to open and close valves many millions of times in the life of an engine at the nowadays mileages of several hundreds of thousands of miles without any failure of those springs with a cyclic rate far exceeding those of any spring gun. Race car engines triple the cyclic rate as well as collapse the springs to within .020" of full coil bind at racing rpms of up to 10,000 rpms without failures in a many thousands of miles. ( MY KZ as an example with over 35,000 mile on the clock and routinely twisted to 10K rpms ).

So is the material that is used in a spring for an airgun that much inferior to what is used in the automotive and cycle world. I just don't see that the spring in an air gun being under any more stress than the ones in an engine that cycle far more times than any spring gun ever will in its lifetime.

You read about the high quality materials used in spring gun springs and also the routine breakage of said springs from to heavy a pellets so I am just trying to understand why one spring will last for 20 plus years and millions of cycles and another will last only a couple year and less than maybe 5000 cycles or less.

I have read this entire post but it still does not compute as why air gun springs are so fragile as compared to other springs that are stressed far greater than any air gun spring can ever be in the guns we have today.

Mike

Thank you Mike, though I should say, before we return to airguns that back in the days (a LONG time ago) I always favoured Ducati engines. I am sure you now know why.

Anyway, coming back to the subject:

The only things in common between motor valve springs and airgun springs is the material they are made from (yes they are made from extremely similar steels), and the fact that they are both coiled. Beyond those two factors there is NOTHING in common.
You are knowledgeable as far as valves and springs are concerned, so let me ask you a few questions and we can then proceed with the subject:

1.- What is the slenderness ratio (length divided by outside diameter) of a motor valve spring? And of an airgun spring?
2.- What is the weight of a valve? And of an airgun piston?
3.- What is the weight of a valve spring and of an airgun spring?
4.- What is the ratio of ID to wire gauge/diameter in a valve spring? and in an airgun spring?
The answer to why valve springs behave completely different from airgun springs is in the proportion of all the dimensions above.

I will await your answers.

Keep well and shoot straight!





Héctor

[Buldawg76]

Sorry about getting sidetrack with bikes.

Back to heavy pellets in spring guns, but also related to engines since they also use springs to open and close valves. I am somewhat baffled and perplexed how the weight of the pellet has any real impact on the life of a spring and how leaving one cocked for long term degrades the spring by significant amounts.

The spring does not know what weight pellet is in the barrel since it will expand at a given rate allowed by its wire diameter and ID/OD and number of coils and amount of compression when cocked. As T-Higgs stated there are many spring guns that use the same spring, piston, guides and so on for 177, 22, 25 calibers in which you a wide variance in pellet weights per caliber of gun.

In relation a motor vehicle engine uses coil springs to open and close valves many millions of times in the life of an engine at the nowadays mileages of several hundreds of thousands of miles without any failure of those springs with a cyclic rate far exceeding those of any spring gun. Race car engines triple the cyclic rate as well as collapse the springs to within .020" of full coil bind at racing rpms of up to 10,000 rpms without failures in a many thousands of miles. ( MY KZ as an example with over 35,000 mile on the clock and routinely twisted to 10K rpms ).

So is the material that is used in a spring for an airgun that much inferior to what is used in the automotive and cycle world. I just don't see that the spring in an air gun being under any more stress than the ones in an engine that cycle far more times than any spring gun ever will in its lifetime.

You read about the high quality materials used in spring gun springs and also the routine breakage of said springs from to heavy a pellets so I am just trying to understand why one spring will last for 20 plus years and millions of cycles and another will last only a couple year and less than maybe 5000 cycles or less.

I have read this entire post but it still does not compute as why air gun springs are so fragile as compared to other springs that are stressed far greater than any air gun spring can ever be in the guns we have today.

Mike

Thank you Mike, though I should say, before we return to airguns that back in the days (a LONG time ago) I always favoured Ducati engines. I am sure you now know why.

Anyway, coming back to the subject:

The only things in common between motor valve springs and airgun springs is the material they are made from (yes they are made from extremely similar steels), and the fact that they are both coiled. Beyond those two factors there is NOTHING in common.
You are knowledgeable as far as valves and springs are concerned, so let me ask you a few questions and we can then proceed with the subject:

1.- What is the slenderness ratio (length divided by outside diameter) of a motor valve spring? And of an airgun spring?
2.- What is the weight of a valve? And of an airgun piston?
3.- What is the weight of a valve spring and of an airgun spring?
4.- What is the ratio of ID to wire gauge/diameter in a valve spring? and in an airgun spring?
The answer to why valve springs behave completely different from airgun springs is in the proportion of all the dimensions above.

I will await your answers.

Keep well and shoot straight!





Héctor

Hector

Yes fully understand why you prefer Ducatis since they employ Desmodronic valve operation that use no springs at all and are a positive open/close system.

1. Don't have direct numbers for the ratio ( slenderness ) of a particular engines valve springs but only to say they are generally a larger ID/OD and much much shorter than an air gun spring IE. say 1 inch ID x 1.300" OD with a .150" wire diameter and 3 inches long as an example, Although newer engines with four and five valves per cylinder are much closer in size to air gun spring if not the same size only shorter since they are controlling much smaller and lighter valves. Air gun spring are from say .560" ID x .790" OD with a wire size of .105' and 31 coils for one of the smaller size springs as an example ( My FWB 300S Maccarri artic single spring ) and up from there.
2. Engine valve weights from max of possibly 8 ounces or so ( I have never weighed any to be truthful ) to as light as 2 ounces for a five valve engine system, air gun piston likely from 1 pound up to 2 or more pounds as I have never weighed them either.
3. Engine valve springs weigh possibly 8 ounces or less again depending on 2 or more valve style heads and never weighed either, Air gun springs from 8 ounces and up to over a pound again just a estimate.
4. Engine spring ID to wire diameter in a two valve engine IE. ID of .750' to 1.250' and wire diameter of .125" to .200' , four or five valve engine close if not the same as an air gun spring if not even smaller as I have seen springs in newer inline 4 cylinder four valve bike engines with spring of .400" ID and wire diameter of .075" being the norm, Air gun spring again as an example my 300 artic spring of .560' ID and .105" wire diameter.

I understand that air gun springs will in fact behave different due to the much increased length over valve springs but the fact that both are subjected to the same harmonics and loads with engine in my opinion being stressed far more than an air gun ever will. Example as in my 76 Harley shovelhead that I have built from the ground up I am opening the valve to .540" with only .060" from full coil bind at rpms of 6000 max and have 40,000 miles on it with no failures and then my Kawi that has .425" valve lift and is .030" from full coil bind and turns to 10,000 rpm routinely with 35,000 miles on it.

Don't quite understand your comment about coils slamming into each other when gun is fired since the spring is expanding all the coils at the same rate is it not so there should be no reason for the coils to touch if the spring is a good fit on the guides, can understand if a loose fit on guides since spring would be expanding and flailing everywhere inside the spring tube.

I guess its what makes up the so called difference of a cheap spring gun and a high end one although the high end ones really don't seem to be much if any better at designing and producing a good fitting spring guide as compared to the cheap one, at least not the one I have built ( D48, FWB 124,300, B40/TX versus Crosman vantage/Quest guns )  IMO.

A beehive spring has been in use in high performance engines for 10 or so years and is one that has its coils formed in an gradual decreasing diameter at one end in order to help control harmonics and spring fracturing from the rapid vibrations encountered in high revving engine with extreme valve lifts and durations. Harleys have been using beehive springs now since 07 in all big twins.

Mike

[K.O.]

Sorry Hector and phoebeisis the Desmo valves had their time but just to breakdown prone and like a solid lifter cam needed constant adjustment if you hammered on it (racing). the positive valve closure allowed more rpm though...

The Ducati killer was the Gixxer and the reason for multi valves was not broken springs it was because like the Desmodromic valve the lighter the valve the higher the rpm you could hit before inertia caused valve float... the other benefit is smaller valves cool quicker...

[39M]

And then came the 5 valve Fizzer. I think they called that the Genesis? 750s were fast, but a buddy had one of the first 1000's and that thing had a powerband a mile wide. I can't think of the name of it, but he had one of those headers with the plates on the end like they put on race boats when they want to keep the noise down.

[DOKF]

Is a fizzer a new ag or alternate mb engine?

We seem to be off track again.

[Buldawg76]

Not me this time

[HectorMedina]

Airgun springs are not all made in the same factory of the same metal alloy any more than hi-performance engine springs are! The airgun manufacturers want to be able to sell enough of the airguns they produce to earn a profit. The average airgun buyer will likely NOT shoot it enough to exceed the cycle life of the average quality stock spring, so why put the more expensive alloy spring in at the factory?

Even the engines you reference use different types of springs for the different jobs they will be expected to perform. All the different calibers/weights of pellets DO NOT perform at their best on that SAME SPRING that comes stock in all the calibers offered. The valve springs in recip engines ARE of much stronger, more resilient steel alloys and tempers than the factory springs in MOST airguns!

There are a VERY FEW makers, worldwide, of HIGH QUALITY springs for use in airguns. The oldest and most well respected innovator/producer in the USA, in this arena since the '80s, is James Maccari of ARH. A coupla others have been trying for decades, and still are, to catch up!

You are MOSTLY right, Terry!

Upwards of 90% of all airguns sold are never really used. Most are used for a day or two and then relegated to a closet for years. So, there is no incentive in producing quality springs for airguns that do not need them.
The real difference however between OEM springs and after market replacement springs is not the material, but the heat treatment and post-heat-treatment. Very few OEM springs are steel shot peened, or stress relieved, or set in a proper setting jig. These three things make a lot of difference in the expected life and performance of a spring. IMHO, the "Set Spring" charge that ARH makes for setting of their non-kit springs is probably the best two bucks you can spend.

The other thing is that manufacturers sell on the speed argument, a highly strung gun that yields 1,200 fps for a few weekends sells better than a finely tuned 875 fps gun that will keep its performance for life.

Where you are not completely right is when you say that engine valve springs are made of "stronger, more resilient, steel alloys"; the truth is that ordinary valve spring (as used by Mercedes Benz, Audi, Chrysler, or GM) would last less than the worst OEM spring in an airgun. The steels are VERY similar, but airgun spring makers use different trace materials to increase the resistance of THEIR springs to fatigue and, therefore, breakage. I am not at liberty to discuss who uses what, but I can tell you that 0.1% of copper content in a steel will make the difference between a great airgun spring and a mediocre airgun spring. Same can be said for other trace materials like Silicon, Vanadium, Indium, Tungsten, Nickel, Chromium, Niobium, Aluminum, Sulphur, Titanium and Cobalt.

Jim Maccari (US) makes VERY good springs, so does Tom Gore (Vortek-US), and Titan (UK) lately has been doing very interesting stuff. There are other spring makers, like Venom, but the first three are the ones that are accessible to most shooters. We should be happy we have here in the US two dedicated spring manufacturers.

The material science of the spring would tend to point out in the direction of the "coextruded" bimetallic wire as the solution to most of out complaints, and there is technology to make at least laminated spring ribbon within economical parameters, the use of three different steels in a square section spring could solve the reduction in power over time, the fatigue and the breakage of airgun springs, the question is whether we will ever pay for it.

Keep well and shoot straight





Héctor Medina

[HectorMedina]

What I would like to see is a beehive spring for an air gun made since they have proven to be far superior to conventional straight wound springs in high performance engines, I bet they would perform equally as well in an air gun if not far superior to what is offered now.

I know I would be willing to pay more for a higher quality spring.

Mike

 

Mike;

I also thought that conical springs could help in the equation, specially if we were to assemble a series of conical elements to make for the whole length of the airgun mainspring. To this day I have not found someone willing to try the idea. Some extremely high quality Match guns of the past have used TWO springs instead of one (counterwound, so as to eliminate the distension torque on the gun), that also brought life cycles in the region of hundred of thousands of shots. So, there is merit in that idea, again, no one of the three manufacturers I have talked to has taken the idea.

For those that are wondering what is a beehive spring, here is a comparison of normal and beehive springs:


Another interesting spring technology is the "wave" spring, but when I talked to Smalley:

http://www.smalley.com/about-smalley-wave-springs

At first they seemed VERY interested in making wave springs for airguns. As soon as I sent them real parameters of operation, they elegantly declined.
In this particular instance, it is the slenderness ratio what would wreck a wave spring from functioning inside an airgun, even if VERY closely guided inside and out.

There are other avenues that could point to the long range development of the airgun mainspring but, I am afraid that given the average value of the spring and the number of cycles it lives, manufacturers are better served by making medium good springs that will get replaced every 10,000 to 15,000 shots than making the "perfect" spring where they can only hope to sell ONE spring during the lifetime of the shooter.

Hope I am making sense.





Hector

[HectorMedina]

Designs using gas rams were an effort to improve on the coil springs.

I personally prefer the gas rams, but may be in the minority.


.

Kim;

Gas Struts/Springs (non adjustable) and Gas Rams (adjustable) have been, up to now, a technology in progress. From the air filled Menaldi in Argentina, then the Theoben that copied the principle, then the Nitro Pistons and Vortek units, they have been inefficient (you need to use 45# of cocking force to get 18 ft-lbs back at the muzzle), unreliable (I once went to a Match with a gas strutted rifle, placed at the top of the pack the first day only to discover that the strut had leaked overnight and that I had no operable gun for the second day of the Match), impossible to repair (once a strut leaks, you have to throw it away, and if it is a ram, the process of setting up the fill pressure is so complicated that you need to do it standing next to a Chrono).

I have faith in the technology for the future and I am in fact awaiting a set of N-Tec piston and trigger units to test on a Diana 54, we'll see when the technology really matures and starts offering what simple steel coil springs offer.

 

Will keep you all posted.





Hector

[Bulsaye]

I scrolled thru this posting and didn't see anything regarding what I consider to be an important factor in spring life: wire diameter and metallurgy. Both JM and I have tested various springs and found that if your wire dia is less than .126" and the metal is music wire; heavy pellets can shorten spring life. If the wire is above .126" diameter, the spring will handle heavier pellets better.
R-9/HW95,98, 50S, 77,97 all use .122" music wire. Early 77's used 3mm (.118). FWB 124 used 3mm also. R7/HW30 was under .110" but I don't recall the exact diameter. Many older spanish guns (up to mid 2000s) used 3mm(.118)..Gamo and Norica for sure.
 Diana magnums have used .126-.128 music wire and they were seriously hardened for added stiffness. This  also made them brittle and subject to failure, even though they were heavier wire.
 Air Arms TX and PS use .128" wire. Several UK Webley models used .128" wire, as has BSA. The Webley Patriot/Kodiaks had .140+" wire, as did the AA Pro Elite.
 R-1/HW80 uses .135: or better wire.
Now- where does pellet weight come in?  For .177's with sub .126 wire, keep your pellets between 7.9 and 9.5 gr for optimum spring life. For .22 with  sub .126" wire, stay between 12-16.5 gr. Guns with heavier wire can handle heavier pellets with little ill effect. Springs that are higher grade than music wire, such as are made with high chrome and silicon (not silicone!) content can be tougher and longer lasting. I know this is the metallurgy JM at ARH preferred.

[MicErs]

I scrolled thru this posting and didn't see anything regarding what I consider to be an important factor in spring life: wire diameter and metallurgy.

Yeah, um, they have been talking about that throught the last forty posts or so...  Maybe scrolling is not the same as actually reading?

[HectorMedina]

Sorry about the detour-but valve springs-undergo perhaps 1 BILLION cycles-and now a days RARELY break.
From what I have read the reason air guns springs- break-
in what would seem to be a MUCH MILDER environment( valve springs are violently "cocked" many many times per second-
But the claim is the Air gun springs break because they are compressed to ALMOST full compression-
Guessing you have to UNWIND THE WIRE-
say 40 coils- 25mm=80mm  circumference per coil- each 80mm coil in a 80mm stroke gun-bent 2mm  for 80mm 1mm per 40mm(oh-I was unclear-just uncoiling one coil-circumference)
a carspring-maybe 35MM=110mm circumference each-perhaps 15 coils??  7.5mm "stroke" so perhaps .5mm per 110mm length- 1mm per 220mm
so the explanation-the air gun springs are BENT MORE- yeah looks like MUCH more 5x as much 220/40=5.5x as much
Looks crude guess like air gun springs are bent 5 times as much as car/motorcycle valve springs-
so makes sense-they break
but like Mike Bulldog says-not so clear WHY heavy pellets are more likely to break the SPRING

On the other hand-as Mike will confirm-CAR/PLANE/MOTORCYCLE valve spring DID break when  high performance folks went to BIGGER/HEAVIER VALVES- it was a HUGE problem-
AND it is the original WHY of 4 valve heads instead of 2 valve heads
It wasn't to increase flow-it was because the heavier BIG valves BROKE the valve springs-
as Mikes Kawa -and harley-and GM/CHEVY pushrod V-8 clear demonstrate-you can flow PLENTY of air thru 1 big hole

So there IS  car/mc engine indications that HEAVY  is tricky
Saying that I STILL am not clear why a 18 grain 22 would be worse than the 13 grain-since the SPRING is THE SAME SPRING- same wire same compression-same everything
WITH the heavy pellet-the spring should  slam forward-more slowly??
So I still dont see WHY the heavy pellet is harder-same compression  same thickness of wire-
only difference is how it slams forward-and seems like it would slam forward MORE SLOWLY??

Hector says heavy does break springs-but still not clear WHY
I believe him- he is very experienced- but WHY?
PS The numbers-on the springs-guesses-made up numbers off top of head-but they are ballpark-and 5 times the bending-clearly shows why the air gun springs break-

WOW!

EXCELLENT ANALYSIS, Phoebeisis!

Yes, the airgun mainspring STARTS more stressed than any motor valve spring. That is the "intrinsic stress" (not always relieved completely), then you add the preload (sometimes we preload our mainsprings by a good 2" this is the "static stress", then you add the compression ratio by taking an 11.75" spring and compressing it to within ½" of solid and then releasing it in one go, this is the "dynamic stress". IF you compress a spring that has a 7.5 mm's stroke to within 1 mm of solid, you are compressing it 87% of its available length, the airgun mainspring is compressed 95% of its available length, does not seem like much until you invert the numbers: CLEARANCE for the engine valve spring is 2½ times (roughly) what it is for the airgun mainspring.

Now, the whole thing goes back to the bounceback of the piston.

If you can picture a relatively long spring that is distending, you can also picture the "longitudinal wave" that the bounceback will create.

Look at this video from minute 1:00



Now, the slinky is a weak and long spring, but look how the piece of thread goes back after being moved when the longitudinal wave hits the end and bounces back, but the maths tell us that in loosely guided airgun mainsprings happens exactly the same thing:



Look at how at milisecond 27 onwards there are NEGATIVE compression ratios, which means that while one coil is distending the next coil is compressing, this is where there are collisions, but the collisions, again, are not the important part, those are a symptom. What REALLY matters is that the stress excursion in a coil goes from positive to negative and positive again, this is equivalent to 3 duty cycles PER BOUNCEBACK.

And if this was a rifle with no guide or with a very loose guide, then there could be up to three bouncebacks, therefore, up to 9 duty cycles per shot.

And it is in THIS last number where the difference between a heavy pellet and a light one makes a huge difference: With a heavy pellet, the mass of the pellet and its resistance to movement create a larger backpressure that in turn is the main "engine" behind the bounceback(s).

It would be interesting to see an XRay of one of those valve springs that broke with heavy valves and compare it to a broken airgun mainspring, I would tend to think that the fractures would be quite similar.

Keep well and shoot straight!





Hector

[Underdog]

In a word: Oscillation. Seems like we want to minimize that as much as possible.
Yeah?

[DOKF]

I knew you would get around to the second paper eventually ...

[HectorMedina]

Yes fully understand why you prefer Ducatis since they employ Desmodronic valve operation that use no springs at all and are a positive open/close system.

1. Don't have direct numbers for the ratio ( slenderness ) of a particular engines valve springs but only to say they are generally a larger ID/OD and much much shorter than an air gun spring IE. say 1 inch ID x 1.300" OD with a .150" wire diameter and 3 inches long as an example, Although newer engines with four and five valves per cylinder are much closer in size to air gun spring if not the same size only shorter since they are controlling much smaller and lighter valves. Air gun spring are from say .560" ID x .790" OD with a wire size of .105' and 31 coils for one of the smaller size springs as an example ( My FWB 300S Maccarri artic single spring ) and up from there.
2. Engine valve weights from max of possibly 8 ounces or so ( I have never weighed any to be truthful ) to as light as 2 ounces for a five valve engine system, air gun piston likely from 1 pound up to 2 or more pounds as I have never weighed them either.
3. Engine valve springs weigh possibly 8 ounces or less again depending on 2 or more valve style heads and never weighed either, Air gun springs from 8 ounces and up to over a pound again just a estimate.
4. Engine spring ID to wire diameter in a two valve engine IE. ID of .750' to 1.250' and wire diameter of .125" to .200' , four or five valve engine close if not the same as an air gun spring if not even smaller as I have seen springs in newer inline 4 cylinder four valve bike engines with spring of .400" ID and wire diameter of .075" being the norm, Air gun spring again as an example my 300 artic spring of .560' ID and .105" wire diameter.

I understand that air gun springs will in fact behave different due to the much increased length over valve springs but the fact that both are subjected to the same harmonics and loads with engine in my opinion being stressed far more than an air gun ever will. Example as in my 76 Harley shovelhead that I have built from the ground up I am opening the valve to .540" with only .060" from full coil bind at rpms of 6000 max and have 40,000 miles on it with no failures and then my Kawi that has .425" valve lift and is .030" from full coil bind and turns to 10,000 rpm routinely with 35,000 miles on it.

Don't quite understand your comment about coils slamming into each other when gun is fired since the spring is expanding all the coils at the same rate is it not so there should be no reason for the coils to touch if the spring is a good fit on the guides, can understand if a loose fit on guides since spring would be expanding and flailing everywhere inside the spring tube.

I guess its what makes up the so called difference of a cheap spring gun and a high end one although the high end ones really don't seem to be much if any better at designing and producing a good fitting spring guide as compared to the cheap one, at least not the one I have built ( D48, FWB 124,300, B40/TX versus Crosman vantage/Quest guns )  IMO.

A beehive spring has been in use in high performance engines for 10 or so years and is one that has its coils formed in an gradual decreasing diameter at one end in order to help control harmonics and spring fracturing from the rapid vibrations encountered in high revving engine with extreme valve lifts and durations. Harleys have been using beehive springs now since 07 in all big twins.

Mike

Thanks, Mike! Just a note, I PREFERRED Ducatis, that was 44 years ago, good memories, but long gone and no interest in getting them back.

Great data and I am very glad that you humoured me, thanks again!

Yes, you are absolutely right, the main difference is in the length; and length brings mass/weight and the chance for a longitudinal wave to settle itself into the operation cycle. Without the length (to diameter), there is no way a spring can experience bounce back.

You are also right that the AVERAGE stress in an engine valve spring is higher than in an airgun spring, BUT, all the stresses in the valve springs go in the same direction, whereas in the airgun spring the stresses even change signs and, for sections of the spring (the beginning and the end), the stresses go from a positive value to the same value but in the opposite direction.
You are probably aware that the overall stress is the mean (average) stress, plus the stress excursion. It is these extreme stress excursions that increase the overall stress in an airgun mainspring to levels that engine valve springs will never experience.

What you refer as the loose guide case is only a matter of degree. Even the tightest guides cannot completely eliminate the longitudinal waves that can settle into long (and unguided for half of their lengths) airgun mainsprings. Here we come to an interesting opportunity: To my knowledge, no one has come up with an outside guide that comes from the piston and extends backwards. If someone was to make an "outside" guide that was sort of a huge top-hat, and that would come back from the piston and engage up to the half of the spring that is unsupported by the inside (rear) guide, we MIGHT have found something that is not only interesting, but useful. The rear guide would provide friction and dampening to the rear section of the spring from the inside, but the forward guide would provide support and friction to the spring from the outside.

What I personally find interesting about Beehive springs is not their external geometry, but their (purported?) egg-shaped sectioned wire. The three dimensional analysis of the dynamic spring stresses gets really complicated, but an egg-shaped section clearly minimizes the stresses on the ID of the spring, while maximizing the resistance on the OD of the spring. Can you tell me if what I understand from them is real? (that the section of the wire they use is eggshaped?)

Square sectioned wire has been tried and it has its own problems, the only way I can see of using advantageously square sectioned wire would be to use a three layered steel ribbon to make those springs and that is going to be hard to test or even try.

Few people realize that airguns have more in common with internal combustion engines than with firearms. So this thread has been a lesson to all (me included).

THANKS!








Héctor

[phoebeisis]

K O Kirby
I was unclear-valve float broke the valve springs-cut from Wiki below-
too much valve
too much acceleration from cam
too little spring
But springs got better-much better-and GMs 5.3  2 valve V-8  easily matches Fords  much more complicated 24 valve Twin Turbo V-6- matches it in MPG HP TORQUE -and is cheaper to build-easier to package-



Like Hector suggests-I wouldn't be surprised to find out that they-valve springs- broke for much the same reason that air gun springs break-some sort of oddball vibration related to the two waves coming together and constructively interfering with one another-effectively increasing the  BENDING  of the wire Just at that point-
This is what the Hector's figure 8 might indicate-both ends -rebound -at different times-and compress MORE that the actual cocking compression
The more compression-means more wire bending on rebound-at end segments- than when cocked
more bending means more likely to break-eventually
The slinky video-cool-love them-good teaching toy-and fun!!
WIKI cut below
i]Valve float is an adverse condition which can occur at high engine speeds when the poppet valves in an internal combustion engine valvetrain do not properly follow the closure phase of the cam lobe profile. This reduces engine efficiency and performance and potentially increases engine emissions. There is also a significant risk of severe engine damage due to valve spring damage and/or pistons contacting the valves.[/i]

Hector-are heavy pellets less far down the barrel than light pellets when the piston slams down- 9.6/1000 sec in one of those papers?If they are them the "back pressure" would be higher-which would help slam the piston back up
Thanks
Charlie

[HectorMedina]

I scrolled thru this posting and didn't see anything regarding what I consider to be an important factor in spring life: wire diameter and metallurgy. Both JM and I have tested various springs and found that if your wire dia is less than .126" and the metal is music wire; heavy pellets can shorten spring life. If the wire is above .126" diameter, the spring will handle heavier pellets better.
R-9/HW95,98, 50S, 77,97 all use .122" music wire. Early 77's used 3mm (.118). FWB 124 used 3mm also. R7/HW30 was under .110" but I don't recall the exact diameter. Many older spanish guns (up to mid 2000s) used 3mm(.118)..Gamo and Norica for sure.
 Diana magnums have used .126-.128 music wire and they were seriously hardened for added stiffness. This  also made them brittle and subject to failure, even though they were heavier wire.
 Air Arms TX and PS use .128" wire. Several UK Webley models used .128" wire, as has BSA. The Webley Patriot/Kodiaks had .140+" wire, as did the AA Pro Elite.
 R-1/HW80 uses .135: or better wire.
Now- where does pellet weight come in?  For .177's with sub .126 wire, keep your pellets between 7.9 and 9.5 gr for optimum spring life. For .22 with  sub .126" wire, stay between 12-16.5 gr. Guns with heavier wire can handle heavier pellets with little ill effect. Springs that are higher grade than music wire, such as are made with high chrome and silicon (not silicone!) content can be tougher and longer lasting. I know this is the metallurgy JM at ARH preferred.

Russ;

There have been passing mentions of metallurgy, but yes, there are things we have not discussed basically because this thread has tried to center on the WHY. Not on the how to avoid , what weight is considered heavy or mid, or what policies of operation would reduce the "damage" to the spring (which was the term used by the original poster).

You are right in that there are a number of things we have not explored nor even mentioned (from short stroked airguns to antibounce pistons) but, I repeat, the thread was dedicated to getting to understand the dynamics of the stresses inside an airgun mainspring when the shot was released.

Thanks for your valuable input, I am sure more than a few will take note and take this as one of the important data to be filed away for future reference.

Keep well and shoot straight!




Héctor