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Thread: Piston gliding

  1. #16
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    I found on my Britannia (slots on bottom of piston) if the piston isn’t consistently central it can affect sear engagement and result in an inconsistent trigger weight.

    I considered buttoning the piston but found a snug piston sleeve and spring guide locked it all in centrally when cocked. Works well.

    Matt

  2. #17
    ccdjg is online now Airgun Alchemist, Collector and Scribe
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    Quote Originally Posted by Mach 1.5 View Post
    Friction is a wasteful by product of metal to metal contact. Instead of large expanses of piston, sliding against the inside walls of the rifle's chamber, actions run on nylatron etc bearings - in fact there's no metal to metal contact at all. Venom and Airmasters was doing this method back in the 80's. No marketing gimmick as owners of their fine rifles will tell you and the fact AA and Walther copied it for their production rifles. Mach 1.5
    Common sense says that any surface to surface contact that reduces friction is going to improve piston efficiency, provided the air seal is not compromised. Which is why for more than 200 years air guns based on the spring piston have used oiled leather seals, thereby avoiding metal to metal contact. Synthetic seals are just a more recent variation on this. Modifying a piston to have minimal friction has been a given for many, many years, so why does a manufacturer have to introduce a new term like "gliding" , as though it is some new hi-tec approach that others have not considered? Smoke and mirrors to push sales, IMO.

  3. #18
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    What Mach 1.5 said.

    In addition, ensuring the rear of the piston is supported means that it moves in a straighter line as the spring unravels, and the tuner can tighten the tolerances between piston, liner, top hat/guides and spring, reducing frictional energy and torque effects, and smoothing the shot cycle.

    Yes, terms like “Lazaglide” were good advertising, and, yes, the cost/benefit ratio of this sort of custom work was always questionable compared to a “spit and polish” service/tune, but it is hard to argue against Messrs Pope, Hancock, Welham, etc.

    It’s also notable that the AA TX and “Walther” LGU/LGV do the same in factory form, and (setting aside some irrelevant issues around the durability of the “Walther’s” trigger group) are generally regarded as exceptionally nice-shooting out of the box.

  4. #19
    ccdjg is online now Airgun Alchemist, Collector and Scribe
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    Yes, I can of course appreciate the technical benefits of piston efficiency optimisaton, it is just the terminology I find irritating when it doesn't really mean anything and is just a sound-bite. A" gliding" piston is no use whatsoever if it leaks air under pressure. Optimising a piston is a complex compromise of many parameters, including frictional resistance at rest and its change with speed, piston weight, geometrical design of the seal, lubricant if any, piston wobble, etc.. It would be more honest to use the term 'fettling' when a piston is being optimised, but this is not exactly a hi-tec term so "gliding" is invented to make it sound more scientific.

    What next? We might yet get 'pellet surfing', 'spring trampolining', and 'trigger feathering' as scientific terms.

  5. #20
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    Look up 'Ludite.....

  6. #21
    ccdjg is online now Airgun Alchemist, Collector and Scribe
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    Quote Originally Posted by jjjohn View Post
    Look up 'Ludite.....
    I did - it's spelt luddite.

  7. #22
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    Quote Originally Posted by ccdjg View Post
    What next? We might yet get 'pellet surfing', 'spring trampolining', and 'trigger feathering' as scientific terms.
    "Tuning"
    Too many airguns!

  8. #23
    ccdjg is online now Airgun Alchemist, Collector and Scribe
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    Quote Originally Posted by evert View Post
    "Tuning"
    That has always been a good word for tinkering with airgun performance. It says what your intentions are without claiming to be some major tehnical scientific breakthrough, like "piston gliding". Better than 'fettling' as that has connotations of a headless chicken.

  9. #24
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    Quote Originally Posted by evert View Post
    Pistons where the sear engages the skirt need to be harder than the pistons with lathing rods, so they will often be harder to machine for synthetic buttons.
    Glue on buttons can be used, but for example BSA supersport/lightning/superstar pistons leve very little room for glue on buttons as they are a quite close fit in the cylinder.
    I have discovered that, also Hatsans and Webleys.

  10. #25
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    Quote Originally Posted by Mr. Gen View Post
    Plastic wont abrade steel - it is the basic principle of synthetic bearings.
    Strange that as I have seen and repaired shafts that have nylon rollers on them!
    Might had been atmospheric dust or moisture that caused the wear to the steel shafts?
    Often thought about using Nylatron (containing lubricant) instead of Delrin.
    Delrin (POM/Acetal) and Nylatron (Nylon) are trade names.
    Last edited by norris; 01-08-2021 at 10:59 PM.

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