Air Rifle Silencer

Discussion in 'Show off' started by Spoon Unit, May 2, 2016.

  1. Spoon Unit

    Spoon Unit Well-Known Member

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    This time, a combination of the knurling library, Fusion 360's threads, and a silencer design from Thingiverse. After much wrangling, I fixed a few issues with the original model and printed this off in around 8 hours, slightly slower than usual, at 100% infill Black eSun PLA.

    Really looks the part and completely stunned the lad who ordered it. It wasn't all sunny though. Initial test at 18 ft/ lbs no problem. Stepped up to 50 ft lbs and fairly surprised it survived. Final test at 75 ft lbs killed it. 8 hours to print, 10 mins to kill. Have done some thinking and a bit of maths and hopefully a redesign should be able to handle the extra pressure by enlarging the initial chamber using a cylindrical (instead of conical) design.

    2016-05-01 20.16.04.jpg 2016-05-01 20.18.35.jpg
     
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  2. Henry feldman

    Henry feldman Well-Known Member

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    Try Nylon. Has a very high tensile strength and is pretty tough.
     
  3. Tony Morel

    Tony Morel Active Member

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    We're sub 12lbs here unless on a firearms certificate so should last more than 10mins.
    Mind you, as I'm using Firebirds exploding targets I'm thinking muzzle noise is the least of the problems
     
  4. Spoon Unit

    Spoon Unit Well-Known Member

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    The weakness was actually due to the strength of inter-layer bonding, not the actual material itself. It was a clean break just before the first baffle. I enlarged the first compartment so that the pressure from the 75 ft lb shot should create an equal or less pressure than the 50 ft lb setting rammed into the first compartment. Will report on success once we test it in a bit. Bit still, the design was good for 18 and 50, so I think it would a solid solution for 12 lb. Thing is, with only 12 lb, the bullet is probably not propelled faster than the speed of sound, so you have no sonic boom to suppress. The 50lb setting propels the pullet at 1400 ft/sec, 280 ft/sec beyond the speed of sound, so the silencer really plays it's part and was completely effective.
     
  5. Henry feldman

    Henry feldman Well-Known Member

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    Hence, nylon. Nylon has hydrogen bonds between the layers making the Z-axis 95+% as strong as x-y. It's a truly awesome plastic.
     
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  6. Mike Kelly

    Mike Kelly Volunteer

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    Nylon layer bond is something to behold. Just a shame it's so difficult to print, and also rather flexible.

    I'd like to try some CF filled Nylon. If it retains the strength of CF and the layer bond of Nylon it would be a bit of a wonder material
     
  7. Spoon Unit

    Spoon Unit Well-Known Member

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    If the cross sections of the Edge prints are to be believed, the additional layer bond strength would be enough to make the print viable as a silencer. However, it's a moot point because
    • It's legal to design
    • It's legal to make
    • You can't fit with registering on your license
    • You can't license without a serial number on the part
    • You can't put a serial on the part with registering to to be able to put serials on
    • Probably no point in continuing
     
  8. mike01hu

    mike01hu Well-Known Member

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    Having just used ColorFab CF20, it's pretty tough and the interlayer bonding seems to be excellent, so I wonder how this would perform in this task?
     
  9. Spoon Unit

    Spoon Unit Well-Known Member

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    Probably good. Unfortunately I cannot easily re-test as the air-rifle was not mine. It's a shame as, even aside from the legality of actually using the print as designed, it was a really interesting test of the kind of workload possible for a printed part from FFF.
     
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