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Thread: Airsporter repair

  1. #1
    Join Date
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    Airsporter repair

    Hi all, I've just been asked for some help in fixing a Mk II Airsporter. It has a problem that that I've not seen before but assume that it's not a unique one and would be interested in hearing of other peoples solutions or ideas.
    The problem is with a stripped thread in the underside of the air chamber, at the front near the loading tap. It's for the short stud (1/4 inch dia.) threaded at each end, that holds the cocking mechanism in place.
    It's a blind hole, the obvious route is to drill and tap it to a larger size, then turn a stud with suitable thread at one end to fit the larger hole.
    Anone here done it before?
    Mel.

  2. #2
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    May 2008
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    Quote Originally Posted by mel h View Post
    Hi all, I've just been asked for some help in fixing a Mk II Airsporter. It has a problem that that I've not seen before but assume that it's not a unique one and would be interested in hearing of other peoples solutions or ideas.
    The problem is with a stripped thread in the underside of the air chamber, at the front near the loading tap. It's for the short stud (1/4 inch dia.) threaded at each end, that holds the cocking mechanism in place.
    It's a blind hole, the obvious route is to drill and tap it to a larger size, then turn a stud with suitable thread at one end to fit the larger hole.
    Anone here done it before?
    Mel.
    Not exactly the same, Mel.

    But I recently fitted a MK6 trigger block and cocking linkage to a MK2 which involved making a stud of 1/4" BSF at the cylinder end dropping down to 5mm through the linkage.

    As you say drilling and tapping at 9/32" or 5/16" would seem the logical way to go as brazing a stud in would cause no end of problems in that area.

    Good luck with it.




    All the best Mick

  3. #3
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    Aug 2011
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    Thanks Mick, I've started digging in the old toolboxes, I'm certain that I have an assortment 5/16 BSF taps and dies in there somewhere. I'd rather not get involved with any sort of heat if I don't have to.
    Mel.

  4. #4
    Join Date
    Jun 2012
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    North Wales
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    If there's enough space I would drill/tap large enough to take a sleeve back to standard. Loctite sleeve then drill/tap to original.

  5. #5
    Join Date
    Sep 2010
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    wigan
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    Why not use a helicoil thread repair , then loctite stud in for extra security.
    !/4 bsf on the bay.

  6. #6
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    Thanks all, good food for thought, I'll talk to the owner before proceeding.
    Mel.

  7. #7
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    sheffield
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    Thumbs up

    Quote Originally Posted by mel h View Post
    Thanks all, good food for thought, I'll talk to the owner before proceeding.
    Mel.


    I have a Helicoil set somewhere Mel, I'll see if I can find it out

    I'll get back to you shortly..



    John
    for my gunz guitarz and bonzai, see here
    www.flickr.com/photos/8163995@N07/

  8. #8
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    sheffield
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    Thumbs down

    Just found it out, I thought it was metric but it's BA

    0BA is the largest, It measures (across the tap) at 7.1mm


    Don't think it will be large enough


    John
    for my gunz guitarz and bonzai, see here
    www.flickr.com/photos/8163995@N07/

  9. #9
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    May 2012
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    wilmslow
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    I have helicoiled a motorbike cylinder block years ago for cylinder head bolts. Strong enough for this application!

  10. #10
    Join Date
    Aug 2011
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    Quick update. I took what I thought to be the most simple route. i was lucky enough to find some BSF taps & dies. I opened the hole and tapped it to 5/16" BSF (the tapping drill size is only a few thou larger than the original 1/4" BSF). Then turned a new stud 1/4" BSF with a short 5/16" BSF section at the end and fixed it into the cylinder with a drop of Loctite. All working nicely. I'm sure that I could have done the job using Metric threads but the owner liked the idea of keeping it Imperial.
    Thanks all, for the advice and thanks John, for the offer.
    Mel.

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