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One more attempt RAW HM1000X Peek valve successful

mubhaur

Member
Nov 8, 2015
1,434
27
Karachi, Pakistan
    Last time when I made the valve poppet out of peek, it couldn't seal properly. 

    Later I went into more details and made it with extreme precision for holding air.

    Amazing results. 

    My RAW HM1000X .25 that was shooting at 875 fps with 34gr jsb pellets now shoots at 935 fps with same pellets, same reg pressure and same HST.

    Looks like I can put a lighter hammer spring now or can reduce the hammer weight.

    20210516_131307.1621262865.jpg
    20210516_131305.1621262865.jpg
    20210516_131256.1621262866.jpg
    20210507_082219.1621262868.jpg

     

    mubhaur

    Member
    Nov 8, 2015
    1,434
    27
    Karachi, Pakistan
      Good stuff, yes give a lightweight hammer a try. The two of them in concert makes for a very snappy shot cycle. Makes the whole shooting experience more enjoyable in a way that’s hard to appreciate until you’ve experienced it.

      Dear,

      I agree to your point but as I have installed SSG which has increased the cocking force a bit more, I prefer to put lighter spring in SSG in order to reduce the cocking force.

      I hope reducing coking force will help longer sear life of trigger.



      Regards, 



      Umair Bhaur 
       
      Due to it's heavy internals the RAWs have quite a long shot cycle and become hold sensitive. Lightening the system will definitely help in many ways. Lighter valve spring for example in combination with the right length of spring will vastly decrease cocking effort because you need less momentum and thus less force from the hammer spring to open the valve (the force to open the valve is a combination of the valve spring force and the reg pressure). Curious to see your outcome!
       

      mubhaur

      Member
      Nov 8, 2015
      1,434
      27
      Karachi, Pakistan
        Due to it's heavy internals the RAWs have quite a long shot cycle and become hold sensitive. Lightening the system will definitely help in many ways. Lighter valve spring for example in combination with the right length of spring will vastly decrease cocking effort because you need less momentum and thus less force from the hammer spring to open the valve (the force to open the valve is a combination of the valve spring force and the reg pressure). Curious to see your outcome!

        A number of combinations of hammer spring, valve spring, hammer weight etc. may be tried to find the best combination with this modified valve. 

        Let us see what I can do over the time.

        Ever since I got these guns, these were great shooters but still by the grace of God over the time many improvements have been made to these guns.

        I can't exchange any new RAW with my RAWs.

        I may be biased. 

        Regards, 

        Umair Bhaur 
         
        • Like
        Reactions: B
        Jan 21, 2018
        2,461
        134
        MS, United States
          That’s true…a lightweight hammer will require more hammer spring tension. If the cocking effort is already objectionable, that would be a step in the wrong direction. I’m just a little surprised that is the case for a .25 cal at ~60fpe, particularly with the mechanical advantage of a sidelever.

          Regarding Broekzwan’s suggestion of using a weaker spring in the valve, that’s worth a try. It’s not so much about making the valve easier to knock open (lift) as it is about helping it to stay open longer (dwell).

          To explain a bit, how hard it is to open the valve is mostly due the air pressure. Using a somewhat arbitrary example to illustrate what I mean…imagine we have a regulator setpoint of 2000psi, and let’s say the valve throat is 0.300” diameter (an area of 0.0706 sq in). The force holding the valve closed is 2000 * 0.0706 = 141lbs. Meanwhile a stiff valve spring is what, 10lbs tops? The spring represents but a tiny fraction of the force holding the valve closed, less than 7%.

          However once the valve is knocked open, the spring plays a much bigger role in how quickly it will close. Let’s assume the valve stem is 3mm…the 2000psi acts against this 3mm to exert a closing force of 22lbs. Another 10lbs contributed by the valve spring is significant…an increase of almost 50%. So by using a different valve spring, we can influence the dwell time quite a bit. For example, using a weak spring can help offset the dwell that is otherwise lost by using a lightweight hammer.

          Having said all that, I want to note that often times this “lost dwell” is precisely what I’m trying to achieve. With many AGs, there is too much to begin with and I’m interested in reducing it. But if the situation requires it, changing the valve spring is one way to do it. Also, I don’t like going too light because it helps with the self-regulation characteristics of the valve. By self-regulation I mean the valve’s ability to produce a stable velocity over a wide range of pressure like an unregulated PCP operating near the top of its bell curve. That characteristic is still very useful in a regulated PCP because no regulator is perfect.
           

          mubhaur

          Member
          Nov 8, 2015
          1,434
          27
          Karachi, Pakistan
            That’s true…a lightweight hammer will require more hammer spring tension. If the cocking effort is already objectionable, that would be a step in the wrong direction. I’m just a little surprised that is the case for a .25 cal at ~60fpe, particularly with the mechanical advantage of a sidelever.

            Regarding Broekzwan’s suggestion of using a weaker spring in the valve, that’s worth a try. It’s not so much about making the valve easier to knock open (lift) as it is about helping it to stay open longer (dwell).

            To explain a bit, how hard it is to open the valve is mostly due the air pressure. Using a somewhat arbitrary example to illustrate what I mean…imagine we have a regulator setpoint of 2000psi, and let’s say the valve throat is 0.300” diameter (an area of 0.0706 sq in). The force holding the valve closed is 2000 * 0.0706 = 141lbs. Meanwhile a stiff valve spring is what, 10lbs tops? The spring represents but a tiny fraction of the force holding the valve closed, less than 7%.

            However once the valve is knocked open, the spring plays a much bigger role in how quickly it will close. Let’s assume the valve stem is 3mm…the 2000psi acts against this 3mm to exert a closing force of 22lbs. Another 10lbs contributed by the valve spring is significant…an increase of almost 50%. So by using a different valve spring, we can influence the dwell time quite a bit. For example, using a weak spring can help offset the dwell that is otherwise lost by using a lightweight hammer.

            Having said all that, I want to note that often times this “lost dwell” is precisely what I’m trying to achieve. With many AGs, there is too much to begin with and I’m interested in reducing it. But if the situation requires it, changing the valve spring is one way to do it. Also, I don’t like going too light because it helps with the self-regulation characteristics of the valve. By self-regulation I mean the valve’s ability to produce a stable velocity over a wide range of pressure like an unregulated PCP operating near the top of its bell curve. That characteristic is still very useful in a regulated PCP because no regulator is perfect.

            Sir,

            I understand that putting a lighter valve spring can only increase dwell that may be offset by reducing the hammer weight. 

            I have often seen that tighter valve spring gives more shots in regulated set ups. The reason I understand is the same as you have mentioned that with harder valve spring the valve closes quickly that help eliminate wasted air.

            I understand that even I use ssg, by side lever action of RAW the extra effort to cock the gun is not much but still I understand that the extra load on sears of the trigger remain increased whether it is bolt action or side lever.

            So by reducing the strength of hammer spring I want to achieve less stress on sears.

            I live in such a country where getting such parts is very difficult. I have to import such precise parts from abroad. So I want to save that hassle expected in future.

            Right now I don't want to put lighter valve spring but I want to put lighter hammer spring. This will bring the hammer spring force around equal to without ssg set up.

            Later I can experiment with developing lighter hammer weight. 

            I thank you for the guidance. I will always need such technical guidance. 

            Regards, 

            Umair Bhaur 
             

            mubhaur

            Member
            Nov 8, 2015
            1,434
            27
            Karachi, Pakistan
              Is there something out of the ordinary with the sear of the HM1000x? As in, is it known to be short-lived? Any decent drop sear trigger group can be expected to last indefinitely.

              That’s my most diplomatic attempt at suggesting you may be concerned about something you needn’t be concerned about.
              1f600.svg



              I get your point. Now I can remain trigger tension free.

              I shall work on light hammer.

              Thank you.

              Regards, 

              Umair Bhaur 
               
              That’s true…a lightweight hammer will require more hammer spring tension. If the cocking effort is already objectionable, that would be a step in the wrong direction. I’m just a little surprised that is the case for a .25 cal at ~60fpe, particularly with the mechanical advantage of a sidelever.

              Regarding Broekzwan’s suggestion of using a weaker spring in the valve, that’s worth a try. It’s not so much about making the valve easier to knock open (lift) as it is about helping it to stay open longer (dwell).

              To explain a bit, how hard it is to open the valve is mostly due the air pressure. Using a somewhat arbitrary example to illustrate what I mean…imagine we have a regulator setpoint of 2000psi, and let’s say the valve throat is 0.300” diameter (an area of 0.0706 sq in). The force holding the valve closed is 2000 * 0.0706 = 141lbs. Meanwhile a stiff valve spring is what, 10lbs tops? The spring represents but a tiny fraction of the force holding the valve closed, less than 7%.

              However once the valve is knocked open, the spring plays a much bigger role in how quickly it will close. Let’s assume the valve stem is 3mm…the 2000psi acts against this 3mm to exert a closing force of 22lbs. Another 10lbs contributed by the valve spring is significant…an increase of almost 50%. So by using a different valve spring, we can influence the dwell time quite a bit. For example, using a weak spring can help offset the dwell that is otherwise lost by using a lightweight hammer.

              Having said all that, I want to note that often times this “lost dwell” is precisely what I’m trying to achieve. With many AGs, there is too much to begin with and I’m interested in reducing it. But if the situation requires it, changing the valve spring is one way to do it. Also, I don’t like going too light because it helps with the self-regulation characteristics of the valve. By self-regulation I mean the valve’s ability to produce a stable velocity over a wide range of pressure like an unregulated PCP operating near the top of its bell curve. That characteristic is still very useful in a regulated PCP because no regulator is perfect.



              While I was talking about the decrease in hammer spring tension I still had my Steyr in my mind. When a Steyr is set at a 16J / 12 ft/lbs setup about 1/3 to 1/2 of the force on the valve comes from the valve spring. It's a lot smaller valve so that makes sense.

              Talking about the valvespring: a mistake a lot of companies make is give the valve a stiff spring with quite some pre-tension. Steyr for example has approximately 30N of pre-tension on the valve and every mm the valve is pushed back adds 10N to force pushing back (spring constant is ~10N/mm). The result is that the hammerspring needs quite some pre-tension for a low power airgun and combines that with some nice hammer bounce.

              If you change the valve spring to one that has the length that it fits right in between a seated valve and the spring seat inside the plenum you take away the extra energy you need to open the valve (yes it might only be 1:15 ratio like you calculated but that's already 6.25% energy you don't need anymore. If you then put a super stiff spring behind the valve you can achieve super fast dwell times but the energy you release is limited or you need to slam that valve with excessive violence. Put a very light spring behind the valve and you can quite easily achieve high powers but low power becomes a problem there. This is where the art is, finding the right spring constant to achieve exactly what you need (there is no one valve spring that works for all cases ;) ).

              Look at a FX hammer, it weighs about 18 grams, compare that to the (give or take) 80 / 90 grams of a RAW hammer and both are able to achieve approximately the same muzzle energy This feels to me like trying to open a door with a truck instead of with your hands while needing a boat load of spring force to force that door back shut to only have it opened for a short time. I have a feeling that with a decent diet and properly calculated or empirically chosen components there is a lot to win in these RAWs without losing power. This isn't only for RAW by the way, there are more brands that don't really seem to get this
               

              TMH

              Member
              Jul 26, 2020
              1,741
              112
              CA, United States
                ...I have a feeling that with a decent diet and properly calculated or empirically chosen components there is a lot to win in these RAWs without losing power. This isn't only for RAW by the way, there are more brands that don't really seem to get this

                I wonder whether this has a lot to do with making a gun for the 'common man' shooter, with longevity (without, potentially, needing a lot of routine adjustments) and diversity of applications in mind.

                Like racing cars and many other highly specialized items, much can be accomplished with weight reductions, different materials of construction, different spring rates, different settings, etc. While this can drastically improve the item's performance and function in specific applications, it can also put the item on the razor's edge of failure.

                The vast majority of gun companies (except for those who are marketing guns specifically for competition use) have to design and tune for a potentially wide range of applications, and a wide range of shooters. Then the competitors will do what they feel is necessary to modify their guns for their application, understanding the potential consequences on the durability of their guns, and the possible need to continually re-tune or replace components which fail.
                 

                mubhaur

                Member
                Nov 8, 2015
                1,434
                27
                Karachi, Pakistan
                  That’s true…a lightweight hammer will require more hammer spring tension. If the cocking effort is already objectionable, that would be a step in the wrong direction. I’m just a little surprised that is the case for a .25 cal at ~60fpe, particularly with the mechanical advantage of a sidelever.

                  Regarding Broekzwan’s suggestion of using a weaker spring in the valve, that’s worth a try. It’s not so much about making the valve easier to knock open (lift) as it is about helping it to stay open longer (dwell).

                  To explain a bit, how hard it is to open the valve is mostly due the air pressure. Using a somewhat arbitrary example to illustrate what I mean…imagine we have a regulator setpoint of 2000psi, and let’s say the valve throat is 0.300” diameter (an area of 0.0706 sq in). The force holding the valve closed is 2000 * 0.0706 = 141lbs. Meanwhile a stiff valve spring is what, 10lbs tops? The spring represents but a tiny fraction of the force holding the valve closed, less than 7%.

                  However once the valve is knocked open, the spring plays a much bigger role in how quickly it will close. Let’s assume the valve stem is 3mm…the 2000psi acts against this 3mm to exert a closing force of 22lbs. Another 10lbs contributed by the valve spring is significant…an increase of almost 50%. So by using a different valve spring, we can influence the dwell time quite a bit. For example, using a weak spring can help offset the dwell that is otherwise lost by using a lightweight hammer.

                  Having said all that, I want to note that often times this “lost dwell” is precisely what I’m trying to achieve. With many AGs, there is too much to begin with and I’m interested in reducing it. But if the situation requires it, changing the valve spring is one way to do it. Also, I don’t like going too light because it helps with the self-regulation characteristics of the valve. By self-regulation I mean the valve’s ability to produce a stable velocity over a wide range of pressure like an unregulated PCP operating near the top of its bell curve. That characteristic is still very useful in a regulated PCP because no regulator is perfect.



                  While I was talking about the decrease in hammer spring tension I still had my Steyr in my mind. When a Steyr is set at a 16J / 12 ft/lbs setup about 1/3 to 1/2 of the force on the valve comes from the valve spring. It's a lot smaller valve so that makes sense.

                  Talking about the valvespring: a mistake a lot of companies make is give the valve a stiff spring with quite some pre-tension. Steyr for example has approximately 30N of pre-tension on the valve and every mm the valve is pushed back adds 10N to force pushing back (spring constant is ~10N/mm). The result is that the hammerspring needs quite some pre-tension for a low power airgun and combines that with some nice hammer bounce.

                  If you change the valve spring to one that has the length that it fits right in between a seated valve and the spring seat inside the plenum you take away the extra energy you need to open the valve (yes it might only be 1:15 ratio like you calculated but that's already 6.25% energy you don't need anymore. If you then put a super stiff spring behind the valve you can achieve super fast dwell times but the energy you release is limited or you need to slam that valve with excessive violence. Put a very light spring behind the valve and you can quite easily achieve high powers but low power becomes a problem there. This is where the art is, finding the right spring constant to achieve exactly what you need (there is no one valve spring that works for all cases ;) ).

                  Look at a FX hammer, it weighs about 18 grams, compare that to the (give or take) 80 / 90 grams of a RAW hammer and both are able to achieve approximately the same muzzle energy This feels to me like trying to open a door with a truck instead of with your hands while needing a boat load of spring force to force that door back shut to only have it opened for a short time. I have a feeling that with a decent diet and properly calculated or empirically chosen components there is a lot to win in these RAWs without losing power. This isn't only for RAW by the way, there are more brands that don't really seem to get this

                  Very constructive and beneficial commitments.

                  I hope this will be very useful for me.

                  Regards, 

                  Umair Bhaur