1. The Forum Rules have undergone some minor changes and updates.  Please take the time to read them; it will only take a couple of minutes of your time. By doing so, you lessen the chance of incurring the wrath of the moderation team or making yourself look foolish to other members.

    90% of users posting adverts in the Sales forums need to be reminded to read the rules as their posts are wrong.  This is unnecessarily time-consuming and will no longer happen - if your advert doesn't follow the Sales Rules it will be deleted and you'll have to start all over again.

    To close this box once you've read it (and the Rules), click on the X in the top right-hand corner.

    Thank you.

    AGF Staff



    Dismiss Notice
  2. A reminder of one of the Forum Rules:

    'Behaviour

    Do not make inappropriate or offensive posts - including threats, harassment, swearing, prejudice, defamation, deliberate insults or name-calling, other negative remarks about this forum, its moderators and administrators or your fellow members. Even if this is just your own personal opinion, RESPECT YOUR FELLOW MEMBERS.'

    There have been changes made to our censoring software in an attempt to help with this growing problem.

    Click the X in the top-right-hand corner to dismiss this notice.
    Dismiss Notice
  3. Dear members,

    Our membership (like our country) consists of people from all walks of life; different in far more ways than can be listed here and each with a different view based on their experience of life - regardless of their colour, religion or cultural heritage. Every single person in the UK has been born of mixed race – we are a multi-coloured and multi-cultural country.

    As many of you are aware there are a handful of individuals amongst this membership that persist in making provocative, inflammatory, racist and otherwise offensive comments. This has been happening across the forum to a certain degree but is most especially prevalent in the Adult section.

    The moderation team has tried to stay on top of this, however unfortunately because of the ‘offensive’ nature of much of its content we don’t monitor the Adult section quite as much as perhaps we should. As a result much of this behaviour has gone unnoticed unless it has been reported to us. While the team always intended to take a "light touch" approach to the Adult section it would seem that some people aren’t quite adult enough to be left unmonitored after all.

    This behaviour is, and always has been against Forum Rules as well as the specific stipulations of the Adults forum and it will no longer be tolerated. We feel it's time to draw a line in the sand and as such from this point onward offenders will receive an immediate and permanent ban from the forum.

    In order for us to achieve our goal of restoring the forum to the friendly and tolerant place it once was, we ask that ALL members be mindful of the content they post and help us to stop unacceptable behaviour by using the 'Report' tool at the bottom of any offending post - the results of which can be seen only by Admin/Moderators.

    You should all receive a copy of this message by PM. 

    To close this message box, click on the 'X' in the top-right-hand corner.

    Dismiss Notice
  4. Hotmail block emails from us entering your inbox. Unless you can setup a safe sender you will not get activation emails from the forum. Please use an alternative provider or complain to Hotmail.
    Hotmail addresses include.

    @Hotmail.co.uk @Hotmail.com @outlook.com @Live.com
    Dismiss Notice
  5. Postings on Politics, Religion & Controversial Off-Topic Material

    The majority of users do not want to read about these subjects and people have left the forum as a result of it – this is after all an 'Airgun' Forum. It’s all very well to say they don’t have to read it if they don't want to, but as most of us use the ‘New Posts’ button there is no easy way to avoid it.

    All AGF staff members are in favour of people being able to discuss what they want, but we have to draw the line somewhere if it is upsetting other users. We don’t want to read about these topics either.

    IMPORTANT- The discussion of politics and religion is no longer allowed anywhere on the forum (including the Adult section).  The only exception is if it's airgun related - they must be put in the Airgun Related Politics section..

    We will not tolerate bullying or personal attacks, racism or any other offensive 'isms'. we will remove these topics from the forum, we will not give you an area where you can abuse each other. We will not hesitate to ban offenders.

    To clear this text box, click on the 'X' in the top right-hand corner.

    Dismiss Notice

Air Rifle Spring durability

Discussion in 'Anything Airgun Related' started by Patrick, Apr 12, 2014.

  1. Patrick

    Patrick Donator

    Messages:
    10,497
    Likes Received:
    2,666
    Location:
    Wiltshire
    The relatively short life of air rifle springs has always puzzled me.Take a 4 cyl car engine for example,if it's run at an average of 2000rpm for 25 mins 3 x a week 50 weeks of the year each spring will compress 1,875,000 times,if my maths is correct.This is far in excess of what any spring in an air gun does,yet they don't buckle or break.Also when an engine is stopped after being run depending on where each cylinder is in its firing cycle some of the springs will be partially or almost fully compressed yet this seems to have little effect on their durability.When you consider the almost infinite number of compressions these springs do in the life of an engine,it's mind boggling yet an air rifle spring does an extremely small number of compressions in comparison yet they have a relatively short life.Must be something to do with the way they're made I presume.Anybody on the forum with spring technology or manufacturing knowledge?
     
  2. Akita177

    Akita177 Addicted to Iron

    Messages:
    4,511
    Likes Received:
    1,046
    The spring is released very violently in a springer and i would also guess under alot of stress when the piston trys to bounce back the other direction.
     
  3. terry1001

    terry1001 Major Poster

    Messages:
    8,498
    Likes Received:
    1,304
    Location:
    Ipswich
    I don't have the technical knowlede to give a definite answer but it seems to me that the air rifle spring is compressed by a greater percentage and presumably this adds a lot of stress to the material. I'm sure that a lot of (replacement) springs and some of the cheaper oem ones are of relatively poor quality but the better ones seem to last quite well. It is likely that the valve springs are a fair bit stronger than they need be to allow for weakening but obviously this is not feasible with an air gun.
     
  4. cloverleaf

    cloverleaf Super Moderator Staff Member Mod/Admin

    Messages:
    17,911
    Likes Received:
    15,158
    Location:
    Oxfordshire
    Several reasons "spring" :)rolleyes:) to mind:

    1. Airgun springs have a much greater length to diameter ratio; meaning they're more prone to buckling.
    2. Airgun springs are compressed to a greater extent than valve springs during use
    3. Most airgun manufacturers use sh*te quality steel.. Air Arms being the one exception in my experience.
     
  5. Dunkman

    Dunkman Posting Addict

    Messages:
    1,678
    Likes Received:
    20
    Location:
    Monmouth
    Let us split the question into its components


    FORCE - Turning stored latent energy into kinetic energy.

    Take a used valve spring out of an engine and compare it to a new one and you will see some shortening of it and a resultant loss in spring force compared to a new spring. The main difference is that in an airgun, the spring is required to provide a very pre-determined kinetic force to the piston and in turn, produce a pre determined muzzle energy. Any degredation in the spring will reduce the amount of energy produced by the rifle and this is what we measure on a regular basis. A valve spring has to provide a force to close the valve but as long as it has enough energy to perform the job, it doesn't matter (Disregarding ultra high performance race engines) if there is degredation in the spring force because it will have been designed from an 'over engineered' perspective to account for the degredation over time.

    In short, a valve spring has a job to do that does not require a very specific amount of spring force whereas an airgun spring is required to produce an exact force time and time again.

    BREAKAGES AND BUCKLING Length really DOES matter (that's what I tell the girls anyway:))

    An air rifle spring is probably circa 7-8 times the length of a valve spring. Some basic air rifles don't have a spring guide or a top hat and when the spring is compressed it is not held in a straight line of compression but can 'cant' over to one side and end up curved like a snake - NOT GOOD. The idead behind a guide and top hat is to keep the spring perfectly aligned and under control whilst compressed and in turn, produce an even, smooth de-compression of the spring upon its release. Consider now the fact a valve spring is 1/7th the length and in turn its aspect ratio of Diameter V Length is considerably shorter so when compressed, there is no tendency to want to buckle or 'cant' and instead can move through a linear line of compression/decompression.

    HARMONICS - Watch out - "Incoming" !!

    That .lovely long spring in the air rifle is suddenly released and all that stored latent energy is instantly turned into kinetic energy as the spring decompresses - all jolly good. However, at the end of its decompression it has to contend with 2 things that contrive to harm it. The sudden stop of the decompression process and the fact that is has squashed a pocket of compressed air that doesn't like to be compressed and wants to fight back (Bounce). This sends a wave of motion in the OPPOSITE direction to the decompression motion whilst there will be a wave of inertial motion still travelling forwards along the spring lenght and at some point along the length of the spring, those two force will meet and conflict one another in a potentially destructive coming together. Have you eve seen a wave break against a sea wall and send back a wave in the opposite direction that then meets the next incoming wave resulting in a huge splash of white foaming water? Its the same principle.

    The longer the spring results in a longer decompression cycle and in turn, the increase in the propensity of the spring to produce an opposite wave force travelling back against its decompression force. It is this shock wave, especially if a rifle does not have a spring guide or top hat, that will eventually lead to a shatter of metal through fatigue, at somewhere near the point the two shock waves meet.

    Conversely, a short, squat valve spring doesn't have to contend with the same amount of these forces under 'normal' operating conditions (again, excluding high performance engines)

    A video showing a wave motion travelling along a spring
    https://www.youtube.com/watch?v=ubRlaCCQfDk

    Hope that all makes sense :)
     
    Last edited: Apr 12, 2014
  6. Tinbum

    Tinbum Delusions of adequacy

    Messages:
    3,681
    Likes Received:
    2,197
    Location:
    At the lathe
    The drop in kits I make support the spring throughout its entire compressed length. This stops buckling and should lead to longer spring life. (In theory)
     
  7. JD

    JD Donator

    Messages:
    7,320
    Likes Received:
    1,026
    Location:
    Dorset
    Ive got a rifle thats had the same spring in it for over 20 years and it still gives the same power, a good tune, lubes and well fitting guides are a must for the longevity of a spring. ; )
     
  8. Patrick

    Patrick Donator

    Messages:
    10,497
    Likes Received:
    2,666
    Location:
    Wiltshire
    Thank you Dunkman,your post has answered my question.
     
  9. tommy gun

    tommy gun Posting Addict

    Messages:
    1,351
    Likes Received:
    81
    Location:
    newcastle upon tyne
    sorry but i think new springs are rubbish, titan and ox what ever make you use a new spring only lasts 3 months shooting [cut down to length] 500 to 750 pellets a week they lose 11 to 15 mil in length and then you have to pack them to get the power back up anybody else had the same trouble
     
  10. JD

    JD Donator

    Messages:
    7,320
    Likes Received:
    1,026
    Location:
    Dorset
    And I will just dis-regard the rest ? how rude.
     
  11. Patrick

    Patrick Donator

    Messages:
    10,497
    Likes Received:
    2,666
    Location:
    Wiltshire
    No I wasn't being rude, not intentionally anyway,all replies were appreciated even your scant reply which contributed virtually nothing to answering the question, it's just that Dunkman's was the most informative but I'll take this opportunity
    to thank the other members for their replies and hope you feel better know
     
    Last edited: Apr 13, 2014
  12. JD

    JD Donator

    Messages:
    7,320
    Likes Received:
    1,026
    Location:
    Dorset
    Over 20 years use, scant ? It gave you an idea of how to make a spring last in a rifle.
     
  13. mattyts

    mattyts Donator

    Messages:
    6,195
    Likes Received:
    140
    Location:
    Yorkshire
    No,I've had a Hatsan 85 fitted with said spring for 3 years,upwards of 10,000-15,000 pellets put through it and power is still running at 11.4,same as the day I bought it
     

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice