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Thread: Thank you friend Deveng

  1. #1

    Thank you friend Deveng

    Thank you friend Deveng


    CYA friends:


    CYA is about advancing rimfire accuracy.


    ______________________________


    I'm posting a picture taken by CYA member Deveng.


    (I'm posting his picture here, so as not to interfere with his post on another thread.)


    This is an excellent picture showing the exact center of the parallel node.






    CYA friends, I've placed a couple arrows showing the vibrating width of the end of the 3/32" rod, which looks to be about 3/4", or so.



    Using the 3/32" rod allows us to visually see this vibration pattern...since it is so flexible compared to a gun barrel.



    The width of the muzzle oscillations of a contemporary size barrel for a RFBR gun is in the .0002"-.0004" range.



    If you look at the length of the parallel node in friend Deveng's picture, with the end of the rod with an oscillation width of maybe 3/4", imagine how long the length of the parallel node is in a gun barrel, with the muzzle oscillating only between .0002"-.0004".



    Thank you friend Deveng for taking time to run the spearment.


    Your friend, Bill Calfee


    ____________________


    PS:


    I feel like I'm going to work friend Deveng to death here.....but...


    What would give a more realistic representation of the length of the parallel node, in an actual gun barrel, would be if friend Deveng could turn the generator off and take a picture as the oscillations were dying down.....
    Last edited by Bill Calfee; 1 Week Ago at 05:40 AM.

  2. #2

    Photo For Bill

    Hi Bill

    Here is a photo with the amplitude dialed down (the height of the sine wave is less)

    I think this is what you were after.


    36Hz low amplitude.JPG


    Regards
    Graham

  3. #3

    Friend Deveng

    Quote Originally Posted by Deveng View Post
    Hi Bill

    Here is a photo with the amplitude dialed down (the height of the sine wave is less)

    I think this is what you were after.


    36Hz low amplitude.JPG


    Regards
    Graham

    ________________________________




    Friend Deveng:


    Yes!


    We've got a lot to discuss, if you're willing.


    Friend Deveng, there's a lot of "talkers" on these Internet forums, but very few doers.


    It's obvious you're a doer.


    And I personally thank you.


    ____________________________



    Thank you for the above picture........it's exactly what I was hoping for.



    Friend Deveng, I use the thin rod to demonstrate barrel vibrations because it allows one to visually see what's happening, to a certain extent.


    We can't see a gun barrel vibrating.


    But, using the thin rod has its drawbacks, because it's like shaking a rope, the harder you shake it the more loops it forms.


    Here's an example of a thin rod showing four nodes.




    We'll discuss this further....


    _____________________________



    The next thing I'd like for you to do...........by the way, when someone is willing to help I can wear them out with questions, etc.


    Anyway, the next thing I'd like for you to do, is to ring a barrel.


    We'll talk more about this down the road.


    Thank you again.



    Your friend, BC


    _____________


    PS:


    CYA friends, please keep something in mind here:


    The vibrations you're seeing in these pictures happens in .001", or less, in a rifle barrel, when fired.




    Last edited by Bill Calfee; 1 Week Ago at 08:28 PM.

  4. #4
    Fantastic!

    Many thanks for that, to both of you.

    So, can you mark the end of the rod, to simulate the crown, and then adding weight until we see the end of the rod not moving not all?

  5. #5

    With Your Permission

    Thank you Bill and Graham for conducting this test, the pictures are a great representation of what takes place. I get asked all the time by our 3P customers "What do you mean when you say you tune the rifle?". The old saying of "a picture is worth a thousand words" couldn't be truer when trying to explain the purpose of a muzzle device. With your permission, I would like to post these pictures to our social media accounts so customers can have a visual representation of the purpose of a muzzle device. Thanks again to both of you for doing this, it's awesome!!


    Best Regards, Anthony

  6. #6
    Quote Originally Posted by DiOrioMFG View Post
    Thank you Bill and Graham for conducting this test, the pictures are a great representation of what takes place. I get asked all the time by our 3P customers "What do you mean when you say you tune the rifle?". The old saying of "a picture is worth a thousand words" couldn't be truer when trying to explain the purpose of a muzzle device. With your permission, I would like to post these pictures to our social media accounts so customers can have a visual representation of the purpose of a muzzle device. Thanks again to both of you for doing this, it's awesome!!


    Best Regards, Anthony

    ______________________


    Friend AD:


    As far as I'm concerned, you most certainly may use this material....


    Friend Deveng will need to answer for himself, of course.


    Your friend, BC

  7. #7

    Yes

    Hi Anthony

    Yes, by all means show anyone you wish especially if they are prepared to listen.


    I too have many questions.

    One should always be asking WHY and have an open mind, you never know what you may learn.

    PedroS I will do your suggestion and make a little simulated MD and add weight to see what happens.

    Regards
    Graham

  8. #8

    Multiple nodes

    Hi Bill

    That is a good picture of multiple nodes.

    wave.JPG

    Something happens in my little vibrating gizmo that does not happen in real life rifle.

    And that is the welding rod is continuously excited by me dialing in a driving frequency (36Hz) causing the vibration to remain for as long as I leave it on.

    I also have the ability to excite it continuously at higher frequencies.

    Some of these higher frequencies causes it vibrate at a higher mode and we end up with 2 , 3 , 4 , or more nodes depending on how high we go with the driving frequency.

    In real life there is no driving frequency just the initial BANG and just 1 bang.

    This on the face of it could only ever make 1 standing wave (at the resonant frequency) that would then slowly diminish with time ( the length of time depending on the internal dampening)

    There is other things happening as well at the same time.

    The initial BANG causes another vibration to go back through the action into the stock and then to wherever and this will be reflecting back to the chamber end of the barrel, (these would be at a different frequency to the resonant frequency of the barrel so unlikely to excite the barrel into multiple nodes) but can move the barrel and change the POI.

    The reflections will be coming off all sort of things such as changes in cross section area, changes in materials.

    This is where a wooden stock has an advantages because of its internal dampening.

    An aluminium stock would be best with inserting a damping material between the stock and action.

    And then there is the compressional wave that happens from the initial BANG, we have only been talking about the transverse wave as both these waves are independent of each other.



    The more you look at it the more complicated it gets, and the more interesting it gets.

    When you truly understand something then you can design improvements and the quality of the improvements will be a reflection of your understanding.


    Regards
    Graham

  9. #9
    I believe the "bang" impulse traveling back and forth on the barrel is the most influential element. The velocity of propagation in steel is around 19000 feet per second. That energy pulse would travel 6 times while the bullet is still in the barrel. The barrel time is around 2.2 milliseconds and I doubt the resonant frequency would have time to set up. No doubt the barrel is moving though. If the peak pulse is at the crown when the bullet exits, the bore would be slightly expanded at that time. Also just before and after that pulse, the bore is slightly constricted. Chris Long did a white paper on this in 2004. Interesting reading that makes sense to me. It is rather technical and the data is for center fire but it should be relative in rim fire as well.
    http://www.the-long-family.com/OBT_paper.htm
    Last edited by jerry; 1 Week Ago at 02:06 AM.

  10. #10

    Friend Deveng....yes, exactly

    Quote Originally Posted by Deveng View Post
    Hi Bill

    That is a good picture of multiple nodes.

    wave.JPG

    Something happens in my little vibrating gizmo that does not happen in real life rifle.

    And that is the welding rod is continuously excited by me dialing in a driving frequency (36Hz) causing the vibration to remain for as long as I leave it on.

    I also have the ability to excite it continuously at higher frequencies.

    Some of these higher frequencies causes it vibrate at a higher mode and we end up with 2 , 3 , 4 , or more nodes depending on how high we go with the driving frequency.


    In real life there is no driving frequency just the initial BANG and just 1 bang.


    This on the face of it could only ever make 1 standing wave (at the resonant frequency) that would then slowly diminish with time ( the length of time depending on the internal dampening)

    There is other things happening as well at the same time.

    The initial BANG causes another vibration to go back through the action into the stock and then to wherever and this will be reflecting back to the chamber end of the barrel, (these would be at a different frequency to the resonant frequency of the barrel so unlikely to excite the barrel into multiple nodes) but can move the barrel and change the POI.

    The reflections will be coming off all sort of things such as changes in cross section area, changes in materials.

    This is where a wooden stock has an advantages because of its internal dampening.

    An aluminium stock would be best with inserting a damping material between the stock and action.

    And then there is the compressional wave that happens from the initial BANG, we have only been talking about the transverse wave as both these waves are independent of each other.



    The more you look at it the more complicated it gets, and the more interesting it gets.

    When you truly understand something then you can design improvements and the quality of the improvements will be a reflection of your understanding.


    Regards
    Graham



    ___________________


    Friend Deveng:



    I highlighted some of your comments, in bold orange.


    And especially important is your last sentence.

    ___________________________


    The vibrations of a gun barrel, when fired, are not a long, sustained occurrence......they're an instantaneous occurrence that quickly dies away.



    Graham, there's been so much misunderstanding, and misinformation, about this subject over the years.

    Your last sentence cleared it up perfectly.


    "In real life there is no driving frequency just the initial BANG and just 1 bang."


    __________________________



    Friend Deveng, when you finish working with modeling a MD for the 3/32" rod test, the next thing I'd like you to do is ring a barrel.


    We can't see the parallel node in the vibration pattern of a gun barrel, but, we can hear it.


    Yes, we can hear it.


    Not only can we hear the parallel node in a naked barrel, if we use a steel MD, we can hear the parallel node being moved to the exit of the crown.


    Graham, you'll discover that barrel ringing is as fascinating as the 3/32" rod test you're running, when it comes to understanding barrel vibrations and the function of a muzzle device.



    Your friend, BC
    Last edited by Bill Calfee; 1 Week Ago at 08:29 AM.

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