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Thread: Tx200 zero transfer port

  1. #106
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    Quote Originally Posted by Artfull-Bodger View Post
    Guys you can use a radiused center bit (as opposed to the 60deg type) for the inlet into the port, they come in many sizes, surely you can find something close to what you want?
    maybe even better...got a link to any online?

    found some

    Product Code: 15.250

    http://www.phantomdrills.co.uk/shop/...ing_drill_bits
    Last edited by bigtoe01; 20-04-2014 at 12:39 PM.

  2. #107
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    looks perfect... less than a tenner too

  3. #108
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    Quote Originally Posted by Artfull-Bodger View Post
    Guys you can use a radiused center bit (as opposed to the 60deg type) for the inlet into the port, they come in many sizes, surely you can find something close to what you want?
    Been using these bits for ages

  4. #109
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    Quote Originally Posted by Jon Budd View Post

    Mote is a 2mm thick 25mm OD washer stuck in the end of the comp tube, with a nicely radiused port, 4mm should be fine. Radius can be quite wide/deep as the port vol is so low.. would only be around 0.5mm of parallel sided port in there (after the entry porting).
    Yep, that would get my vote.
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  5. #110
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    Guys, maybe not the right place, and maybe a curveball,

    But.......Are there any situations where a LONGER transfer port can actually be beneficial? I accept that shorter ports indeed seem to result in higher efficiency, but would it be possible, for certain applications, that a longer port could improve the shot cycle and resultant smoothness, reduced recoil /surge??
    THE BOINGER BASH AT QUIGLEY HOLLOW. MAKING GREAT MEMORIES SINCE 15th JUNE, 2013.
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  6. #111
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    New port & compression plug fitted

    OK it's done, new compression plug made, transfer port to Tony's drawing (as near as possible). I did miss the port length by 0.5mm......a bit short then...0.25mm of that was in the middle so the rest on each end.........apologies..trust me it's quite fiddly!

    The edges are not as sharp as the images show as images were taken at random stages prior to finishing.

    I did what I said I was going to do & converted the plug & barrel to accept a Feinwerkbau 300s seal. The blue seal in the images is not the one fitted, the item shown is a second hand part for fitting trials, these things are £14.00 a pop so didn't want to risk a new one which is now in the rifle.

    I had to sleeve the barrel so used what was to hand. For anyone wanting to do this the angle is 24.25 degrees. Also I had to re-thread as I had previously had to machine the original thread away for the previous incarnation.

    A few images here

    Used the same spring, seal etc for the Vo tests to try to keep some sort of constant, No relube or any other alterations. the average Vo is minus 60fps over the barrel being on the piston seal face.

    I have my own thoughts on this!
    Last edited by wonky donky; 20-04-2014 at 07:07 PM.
    IF IT'S NOT BROKE.........DON'T FIX IT!

  7. #112
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    you lost 60fps...wow!

    what was consistency like?

  8. #113
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    Quote Originally Posted by bigtoe01 View Post
    you lost 60fps...wow!
    But did the stroke also reduce by the length of the port ?


    My own approach to testing transfer port efficiency is a real PITA and takes too much time, but I think it works... the only thing I keep constant is the swept volume/stroke, and I then determine the maximum power I can get out of each configuration without inducing slam (so practically, no less than 20 fps differential between 7.9s and 8.4s). I change piston weights and springs, sometimes even seals, because in practice - why not ? That's what I'd actually do if I were given a gun (with a fixed swept volume / port configuration) and told to make the most of it...
    Obviously you need to start with a fairly short stroke to keep things sensible...

    But it takes ages...

    ATB - JB
    Last edited by Shed tuner; 20-04-2014 at 09:00 PM. Reason: grammar !

  9. #114
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    The point was to try a choking port, same stroke (Dave needs to confirm), same piston seal and we see a 60fps drop....as long as that breech seal is sealing correctly we need a rethink.

    So....if the stroke is the same this choking port is not as efficient for power...BUT is the consistency better?

  10. #115
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    Stroke was the same, my misunderstanding...
    Maybe the volume loss in the port was too great ?

  11. #116
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    Everything the same, stroke etc. unchanged. The results are as I expected, so no surprise.

    I have now loctited the barrel in place as I'm keeping the port length but will change the port profile with a sleeve at some point.
    IF IT'S NOT BROKE.........DON'T FIX IT!

  12. #117
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    Quote Originally Posted by Jon Budd View Post
    Thanks Leo, good info, and 15 FP from a 75mm stroke/26mm bore is definitely very efficient.
    YW Jon.
    Efficiency and smoothnes are the things I'm looking for. I don't care about high power. That I'm at 15FP is just because my reference-97 has the same Oem-spring inside. And you have to start somewhere, right?
    Next step is putting this system into my other 97 as the "new reference" and bring the power of my testing-rifle down to HFT levels.
    Gonna use a better brand of spring this time 'cause I feel & hear that the OEM is not always doing what it's supposed to do. Sudden single drops of >15fse are pointing in that direction to.

    Just fiddlin' around a bit more. As we say in Holland: "Het houdt je van de straat".


    ATB, Leo.
    Last edited by Leo Bokkum; 22-04-2014 at 06:03 AM.

  13. #118
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    If you want a reference, I'm at 70mm with a 25mm bore for 12FP... with your port and larger bore, I'd start the 12FP gun at 65mm stroke and work from there !

  14. #119
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    Some food for thought, 7 out the top 10 at the recoiling championship were HW's, im wondering with all this work we have been doing whether we will see a more even balance next time with AA's and the new LGU which I know has good specs already

  15. #120
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    Quote Originally Posted by bigtoe01 View Post
    Some food for thought, 7 out the top 10 at the recoiling championship were HW's, im wondering with all this work we have been doing whether we will see a more even balance next time with AA's and the new LGU which I know has good specs already
    depends on if they eat dodgy burgers and get the s**** all night on the Sunday and Monday morning

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