Results 1 to 15 of 15

Thread: Slingshot hammer

  1. #1
    Join Date
    Aug 2016
    Location
    Melton Mowbray
    Posts
    815

    Slingshot hammer

    Today I tested my slingshot hammer for my Brocock Contour.

    Whilst it cocks and releases it won't open the valve.

    I assume the slingshot needs to be heavier.
    The original hammer had 10mm of travel which I duplicated. I then increased this to 15mm. To increase the stroke I have to reduce the length, and hence the mass of the slingshot.

    Any pointers?


    Dear Spell checker, that's not what I was trying to say.

    I am getting tired of your shirt.

  2. #2
    Join Date
    Apr 2002
    Location
    Near Wimbledon, SW London, or Lusaka, Zambia
    Posts
    23,954
    cant tell from the pics.. dos the smaller metal cylinder get accelerated by the hammer spring, then arrested allowing the outer hammer to continue? im trying to work out if you are loosing too much hammer spring energy moving mass...
    Always looking for any cheap, interesting, knackered "project" guns. Thanks, JB.

  3. #3
    Join Date
    Aug 2016
    Location
    Melton Mowbray
    Posts
    815
    The outside is a cage which holds the slingshot. The valve protrudes by a millimetre so the slingshot needs to sit inside the cage.

    The spring holds the slingshot to the rear of the cage during cocking and sits inside the hammer spring guide (the white bit).
    It's the closest I could make to the original hammer
    Dear Spell checker, that's not what I was trying to say.

    I am getting tired of your shirt.

  4. #4
    Join Date
    Apr 2002
    Location
    Near Wimbledon, SW London, or Lusaka, Zambia
    Posts
    23,954
    ahh OK, now I see, sorry... so if the hammer (cage) is quite heavy, it's going to be taking a lot of spring energy, which isn't purposeful in terms of providing energy to hitting the valve (which is only opened by the slighshot piece). What is the weight of the cage and also the weight of the slingshot part ? That'll probably answer the question...
    Always looking for any cheap, interesting, knackered "project" guns. Thanks, JB.

  5. #5
    Join Date
    Apr 2002
    Location
    Near Wimbledon, SW London, or Lusaka, Zambia
    Posts
    23,954
    PS some other minor design improvements to consider... (but no point until the cage mass issue is sorted)
    - ensure the spring that holds the slingshot back is as light as possible
    - the central bolt that passes through the small hole inside the hammer/cage/body should be smooth at that section

    PPS A Ti cage might work, ali will wear
    Always looking for any cheap, interesting, knackered "project" guns. Thanks, JB.

  6. #6
    Join Date
    Jul 2015
    Location
    Kings Lynn
    Posts
    235
    I would suggest that the actual hammer part is not heavy enough to retain enough inertia to open the valve or that the spring is not strong enough to provide enought energy, when i make SSGs i ofter need to increase the hammer spring strength to provide the extra innertia to still open the valve after the preload is removed.

  7. #7
    Join Date
    Apr 2002
    Location
    Near Wimbledon, SW London, or Lusaka, Zambia
    Posts
    23,954
    Quote Originally Posted by Tricky-Ricky View Post
    I would suggest that the actual hammer part is not heavy enough to retain enough inertia to open the valve or that the spring is not strong enough to provide enought energy, when i make SSGs i ofter need to increase the hammer spring strength to provide the extra innertia to still open the valve after the preload is removed.
    yup.

    I was actually going to suggest SSG route might be easier too...
    Always looking for any cheap, interesting, knackered "project" guns. Thanks, JB.

  8. #8
    Join Date
    Aug 2016
    Location
    Melton Mowbray
    Posts
    815
    Having had good look on how I can improve things, an SSG would be the easier route.
    I hope to make one internal to the hammer,
    fixed at the rear.

    Needs a bit of thought first.
    Thank you for your help.
    Dear Spell checker, that's not what I was trying to say.

    I am getting tired of your shirt.

  9. #9
    Join Date
    Apr 2002
    Location
    Near Wimbledon, SW London, or Lusaka, Zambia
    Posts
    23,954
    Quote Originally Posted by Neil54 View Post
    Having had good look on how I can improve things, an SSG would be the easier route.
    I hope to make one internal to the hammer,
    fixed at the rear.

    Needs a bit of thought first.
    Thank you for your help.
    I've done a few SSGs, i stuck up a post on here a while ago. The telescopic spring guide version is anways an option, except for extremely short hammer strokes, and fits inside. I don't think external devices are a realistic option due to UK power laws, unless on bullpups where external to the action is still internal to the stock (whcih I did on my Kral and JKHan)
    Always looking for any cheap, interesting, knackered "project" guns. Thanks, JB.

  10. #10
    Join Date
    Jul 2015
    Location
    Kings Lynn
    Posts
    235
    I have an external SSG adjustment on my R10 (only way to do it), don't think it's a problem as it not a problem having anti tamper removed from air guns,
    Looking atg that hammer you could do something similar to my Kral hammer if you have a lathe.

    R10


    Kral

  11. #11
    Join Date
    Aug 2016
    Location
    Melton Mowbray
    Posts
    815
    Thank you for the pictures.

    Look like a mk2 is on the cards.
    Dear Spell checker, that's not what I was trying to say.

    I am getting tired of your shirt.

  12. #12
    Join Date
    Jul 2015
    Location
    Kings Lynn
    Posts
    235
    Some ideas for you.







  13. #13
    Join Date
    Aug 2016
    Location
    Melton Mowbray
    Posts
    815

    Ssg

    Here is my mk2 shown alongside the original hammer in black.


    Promising results although I feel the spring is over compressed.
    Works well. Instant noise reduction, I thought it wasn't working properly.
    Thank you for all your help and advice.
    Dear Spell checker, that's not what I was trying to say.

    I am getting tired of your shirt.

  14. #14
    Join Date
    Sep 2012
    Location
    Chelmsford
    Posts
    1,547
    How are your results with the ssg Neil

    Ive made a few for various pcps Ive owned and just now been tinkering with a kral, Ive found the best float to be 0.5 to 1.00mm any bigger and the fps spread rises and Ive never matched the consistency of a well set up H’spring and not always gained shots either, get it right and they do work well


    Chris
    bigtoe, Harry, hydroclamp, jpsnorton, gayle89, mark410, Stu83, smallholder1, wellhouse0, readingcop, sir-slots-alot, danco1987, Stevenb, DarylDiane, simpleSimon, Ratinator, Milek, Josh, Maxtich, Woodsie99, Ozzie, master_shriller, niloc, Drake267, deejayuu, shootingstars

  15. #15
    Join Date
    Apr 2002
    Location
    Near Wimbledon, SW London, or Lusaka, Zambia
    Posts
    23,954
    nice Neil. That's the design I call "telescopic spring guide" as it's completely internal. There's probably another name out there...
    The noise reduction these give is really impressive.
    Always looking for any cheap, interesting, knackered "project" guns. Thanks, JB.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •