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tonybubb

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    tony bubb
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  • Interests
    Model Engineering especially airguns
    Shooting generally
    Hot air ballooning
    Vintage and modern sports cars

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  • Region OR County OR State of residence
    West Sussex
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    UK

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  1. tonybubb

    GC2 Action .

    I am not defending the original construction of the GC2 and I am not suggesting that it should be reintroduced or copied. I just believe that, like the Sharp Innova, it was a stepping stone or a signpost pointing the way for further development. Having spent a lifetime as a Patent Attorney in general practise perhaps my brain may be more trained to see these signposts and usually the expected development follows, but not in this case. At first I thought that the Chinese Huben K1 was such but it seems that it is still inconsistent due to its reliance on regulators to act as pressure valves. I am not a RFD or a gunsmith, just a hobby tinkerer with a model engineering workshop and a little time to play with new ideas. The Sharp Innova was my first pneumatic rifle and I was so impressed that I wanted to make something similar but without the disadvantages. After several efforts I am still trying to improve on what I have done so far. I have in my head another new design which, in theory, is the answer to everything. Some of the building blocks I have made for other reasons and I know to work, but with limited workshop time it may be a while before I can prove anything.
  2. tonybubb

    GC2 Action .

    If the air flows through the thread while the hammer valve is open then it must be moving fast. If the thread is only used for very slow filling of a dump valve between shots there should be no temperature rise. There should also be negligible pressure drop across the regulator valve.
  3. tonybubb

    GC2 Action .

    I have just seen a post on John Bowkett’s FB page that says that throttling with a screw thread is a technique also used with regulators for hammer actions. I suppose that it is a matter of how much throttling is needed.
  4. tonybubb

    GC2 Action .

    I wonder if that is true and would like to experiment with that. If you ignore the flow through the regulator the valve should always shut at the same pressure since the pressure is balanced by the area of the piston and the opening force of the spring, which stay constant. But when there is a flow through the regulator there is also a pressure drop across the valve which upsets the balance and introduces a variable force that affects the closing of the valve. So by throttling the flow the closing pressure should become more consistent. The problem, or possibly the solution is that this will only work with a dump valve.
  5. tonybubb

    GC2 Action .

    Does it, or the others, have the feature referred to in the Cardew Patent, namely the air feed via a screw thread to throttle the flow of air to the regulator. This is what would make it so consistent. I don’t know about the three other regs, do you have links to mechanical details?
  6. tonybubb

    GC2 Action .

    Or in any weather? Does anyone have a rifle with a normal regulator where the pressure at the output of the regulator stays absolutely constant over the whole shot count? I suspect that there is always a slight fall in the regulator pressure. But if there is a perfect normal regulator out there I would like to know how it works. The best solution I have seen is two regulators in series, but this only reduces the pressure drop it does not eliminate it.
  7. tonybubb

    GC2 Action .

    That is what it has been, just something to keep me sane in my retirement, although not completely successful in that, Ho Ho, HaHa, HeeHee - - - Tony.
  8. tonybubb

    GC2 Action .

    That consistency is due to the regulator, because the design is such that the pressure in the dump valve is always constant regardless of the varying pressure in the main reservoir. That is because the dump valve chamber is charged slowly so that the pressure at the input of the regulator has no effect on the set pressure at the output. No hammer valve regulator can do that, so far as I know, because there is always a flow through the regulator during a shot and the hammer valve has to compensate for the varying pressure at the input to the regulator. I know what you mean about the perfect trigger, I still miss my Walther KKM that I had to give up when I stopped competing in small bore rifle. Tony
  9. tonybubb

    GC2 Action .

    Hallo Holly and thanks for your interest. My design is nothing like the GC2 in format. The only common features are that it uses a dump valve and a regulator. The real secret of the GC2 lies in the regulator but Gerald Cardew’s mistake was to combine the regulator and the trigger mechanism. An engineering nightmare. A simple form of his regulator could have been fitted to the air input of a simple dump valve based on the Sharp Innova and Job Done. But my object was also to eliminate the basic inefficiency of the dump valve and that I have achieved. I would expect to obtain about 200 shots from a 250cc cylinder with a sub 12ft/lb rifle. Now to modify my prototype to eliminate the inconsistency and I shall be getting somewhere. Tony
  10. tonybubb

    GC2 Action .

    This is the post that prompted me to reply in my previous post.
  11. tonybubb

    GC2 Action .

    Came rather late to this Topic but I have wondered for a long time whether a modern alternative to the GC2 would be a commercially viable proposition. No need to buy any rights from anyone as the Cardew Patent has long since expired and I wouldn’t want to repeat all the over complicated design faults of the original. I have been experimenting for a long time trying to build a rifle that would perform as well as the GC2 but would use air more efficiently and would fit in with modern fashions such as the Bullpup, semi auto mechanism etc. The Huben K1 is a possible role model. I came very close recently but test results on a prototype showed disappointing consistency and I gave up until a recent Eureka moment has prompted me to try again. My motivation in this is not to make money but to prove that Gerald Cardew was right to avoid using a hammer action and that the future for high quality airguns lies in a pure pneumatic hammerless action. The Huben K1 has received much attention in USA as it has shown that a hammerless action can produce power well beyond that of a conventional airgun. There is doubt about its accuracy however, as reported on tha AIRGUN NATION Forum. If I am able to produce a prototype that proves my point would anyone be interested or would the vested interests in hammer action PCPs be too much to allow the idea to flourish ? I am too old to consider forming an airgun manufacturing company and am not a RFD anyway. But watch this space as I may soon have “son of GC2”.
  12. tonybubb

    Drulov DU10 lubrication

    Thanks Nick for the tip. Although I don’t use capsules. I have the 250cc bulk filling cylinder and several old CO2 fire extinguishers for recharging it which may last me for life. I did lubricate the piston with DriSlide when the pistol was stripped and it allegedly leaves a permanent layer of lubricant, but I doubt whether it would resist CO2 vapour for long so I shall follow your advice. Tony
  13. tonybubb

    Drulov DU10 lubrication

    What lubricant is best for the DU 10? After long storage have just resurrected mine and am stripping it for a service and possible seal replacement. The moving parts seem very dry. The piston on the hammer looked as though it had traces of moly and I wonder whether to relube with DrySlide or oil such as BreakFree. Any Comments? Tony
  14. tonybubb

    Non mechanical regulator

    Thanks Jon. I can't use a semi balanced regulator as it does not give an absolutely constant output pressure. My valve system Is so sensitive to regulator pressure that even a change of 50 psi during exhaustion of the main reservoir would be unacceptable. My solution is to use an unbalanced gas spring with the pressure of the gas in the spring being almost the same as the desired output pressure. It is also manually adjustable during use so that the output pressure can be adjusted using a built in pressure gauge. This would take account of possible temperature changes. The power output is directly proportional to the regulator pressure so the maximum regulator pressure would need to limited for sub 12ft/lb. Tony
  15. tonybubb

    Non mechanical regulator

    He may be interested if the project comes to fruition as my object is to build something that will equal the GC2 in consistency without the complication, muzzle blast and low shot count. I could even make it semi automatic if that were allowed. Tony
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