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Thread: A picture of the updated Diana piston with the new crimp.

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    A picture of the updated Diana piston with the new crimp.

    I thought some of you guys might like to see this pic that has been posted on the DWC, the original crimp is also a bit deeper by .020"



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    That looks like it might have been made in China.

    Many years ago.
    Arthur

    I wish I was in the land of cotton.

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    Quote Originally Posted by Arthur John Smithsplease View Post
    That looks like it might have been made in China.

    Many years ago.
    Why

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    If the groove in the piston rod is where the original crimp is then the second crimp is likely to make it more unstable
    Stupid Idea I reckon !
    ( hope I don't have to explain )

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    Quote Originally Posted by mallyally View Post
    If the groove in the piston rod is where the original crimp is then the second crimp is likely to make it more unstable
    Stupid Idea I reckon !
    I wonder if the piston rod is now longer.

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    Quote Originally Posted by mallyally View Post
    If the groove in the piston rod is where the original crimp is then the second crimp is likely to make it more unstable
    Stupid Idea I reckon !
    ( hope I don't have to explain )
    I think it's a pretty bad idea in the first place using a crimps to hold the whole thing together, would the deeper crimps and the new crimps make the piston even more out of round? (yet another problem they've had) surely they should realise that the metal has to go somewhere when it gets compressed and it doesn't always go inwards.

    Pete
    BSA Supersport Custom Lightning .25 ~ BSA Mercury Challenger Lightning .177 ~ 2 x BSA Mercury S .22 ~ BSA Airsporter S carbine .22 ~ BSA Airsporter RB2 carbine .22 ~ 2 x BSA Challenger .22 ~ Air Arms Prosport .177 ~ Air Arms Combat .22.

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    I really wish I hadn't seen that Barry.

    After turning god knows how many rifles out with iffy pistons, they've now decided they need to crimp them a little harder ??

    Looks like someone on work experience has "had a go"

    On the list of top ten attempts to bodge a cure, this has pipped HW's 99"cure" by a fair margin.

    Certainly put the lid on me owning another Diana.
    Last edited by robs5230; 14-01-2018 at 08:50 AM.
    some rifles, not too many but definitely not enough

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    Quote Originally Posted by robs5230 View Post
    I really wish I hadn't seen that Barry.

    After turning god knows how many rifles out with iffy pistons, they've now decided they need to crimp them a little harder ??

    Looks like someone on work experience has "had a go"

    On the list of top ten attempts to bodge a cure, this has pipped HW's 99"cure" by a fair margin.

    Certainly put the lid on me owning another Diana.
    My thoughts exactly, I think my 34 may be getting sold soon.

    Pete
    BSA Supersport Custom Lightning .25 ~ BSA Mercury Challenger Lightning .177 ~ 2 x BSA Mercury S .22 ~ BSA Airsporter S carbine .22 ~ BSA Airsporter RB2 carbine .22 ~ 2 x BSA Challenger .22 ~ Air Arms Prosport .177 ~ Air Arms Combat .22.

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    Quote Originally Posted by look no hands View Post
    My thoughts exactly, I think my 34 may be getting sold soon.

    Pete
    Yep.
    I may offload mine now.
    We may have to be quick though
    some rifles, not too many but definitely not enough

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    I very much doubt the piston rod is longer. That would mean reworking one of the major parts in this assembly. They clearly have no intention in doing that.

    They are mass producing these things to a minimum cost or there would have gone more effort into this than smashing them all together with a load of pressure.

    It looks like they have realised that some problems have arisen re loose rods and the odd rod coming out. So the answer is to give it a second smash together.

    Not engineering purity ... but if it works it works. They aren't looking to flog Olympic Match accuracy here in these type of rifles. Just mass produced samples that will give most of the world decent enough power from a simple break barrel airgun to pop some tins in the garden or some bushy tails in the trees out to about 40 yards.

    Unlike the 'Tune them to the Nth to squeeze another 3% accuracy out of them' brigade on here ... Diana aren't interested in that.

    A 2 lb hammer knocks nails in. It doesn't have to be engineered to a tolerance of 0.001". It doesn't have to be Gold plated. You just want it to knock nails in and the head doesn't fly off and kill the bloke behind you. If this extra crushing fixes the safety issue ... it's sorted.

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    I've never experienced piston/rod failure on any Diana Ive owned going back to 1986. I have had probably over a dozen Dianas with this method of piston construction and experienced varying degrees of out of roundness, which is annoying enough, but nothing more serious.
    I believe that there have been big variations in the hardness of Diana piston etc. steel over quite a number of years. The steel obviously reacts differently to the pressures of crimping. This is how the out of round issue effects some guns much worse than others. And probably why there has instances of rod detachment.
    Obviously, there is a happy medium that Diana have found the vast majority of the time. But you can't help thinking they should revert back to their old system or use a new method.
    It would probably restore confidence which is critical. Especially at this juncture.

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    With respect ...

    They are probably more interested in their sales figures, and profits, at board meetings than a few posts from a few owners on internet boards who would ideally love the pistons to be fully machined and perfectly round.

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    Quote Originally Posted by bozzer View Post
    With respect ...

    They are probably more interested in their sales figures, and profits, at board meetings than a few posts from a few owners on internet boards who would ideally love the pistons to be fully machined and perfectly round.
    That's the problem with every company who makes whatever, look how long it took HW to kind of fix the 99, if Walther can make the same style of piston (central rod) and not have any problems with it then surely Diana can do the same, if you look on the Sportwaffen Schneider site, you can pick up a new Walther LGV piston with bearing and seal for 33 euros, now to me that's pretty cheap but what must it cost Walther (or whoever makes it for them) to make? considering S.S. buy them in and have to sell them to make a profit and the same goes for Walther selling them, they still have to make a profit, so it can't cost heaps to make a good quality piston which ain't held together with crimps, even BSA managed to do it with the Airsporter for christs sake.

    Pete
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    Walther had problems with the latch rods originally iirc. They just pinned it in the end & that was the end of the problem. The Diana looks like a make do & mend affair rather than a failsafe fix to be honest.

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    Quote Originally Posted by bozzer View Post
    I very much doubt the piston rod is longer. That would mean reworking one of the major parts in this assembly. They clearly have no intention in doing that.

    They are mass producing these things to a minimum cost or there would have gone more effort into this than smashing them all together with a load of pressure.

    It looks like they have realised that some problems have arisen re loose rods and the odd rod coming out. So the answer is to give it a second smash together.

    Not engineering purity ... but if it works it works. They aren't looking to flog Olympic Match accuracy here in these type of rifles. Just mass produced samples that will give most of the world decent enough power from a simple break barrel airgun to pop some tins in the garden or some bushy tails in the trees out to about 40 yards.

    Unlike the 'Tune them to the Nth to squeeze another 3% accuracy out of them' brigade on here ... Diana aren't interested in that.

    A 2 lb hammer knocks nails in. It doesn't have to be engineered to a tolerance of 0.001". It doesn't have to be Gold plated. You just want it to knock nails in and the head doesn't fly off and kill the bloke behind you. If this extra crushing fixes the safety issue ... it's sorted.
    Very nicely put and makes perfect sense....

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