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Daniel Beaver

Member Since 19 Sep 2008
Offline Last Active Yesterday, 07:32 PM

Posts I've Made

In Topic: Brass Breech LS destroying worker darts

11 June 2019 - 08:26 PM

It sounds like you're not getting a good seal when the breech is closed.


In Topic: Breech modification in a tri-strike

06 June 2019 - 09:11 PM

You'll want the breach to open just far enough to pick up the half length darts. First step would be to get some magazines that use half length darts, so that you can kinda eyeball what you need to do to the breech.

In Topic: The History of Nerf Modding archival project

07 May 2019 - 08:57 PM

I'll jump on. This is the right place to find information.


In Topic: Dart foam is cracking, but the heads are not blowing off.... Help plea

28 April 2019 - 09:48 PM

To follow up on what we talked about at the war:

I think what's happening is a combination of a short, tight barrel and a small-radius plunger tube, combined with full length darts, means that when the dart is half-way out of the barrel, the pressure inside the hollow stem of the dart is quite high relative to atmospheric pressure. Cylinders that are experiencing stress due to positive pressure on it's inner surface will tend to split in the longitudinal direction. This is because axial stress is about twice as high as radial stress. The splitting you see is in the direction you would expect if the pressure inside the dart got high enough to rupture the foam. You normally only see this kind of splitting on air valve blasters with large volume pressure chambers, such as Big Blasts or Jobars. With those blasters, the pressure in the barrel remains quite high even when you're using a very long barrel - they're releasing so much high pressure air that even a very long barrel doesn't drop the pressure very much.

 

pressure_vessels.png

 

The solutions to this problem are:

  • Lower the peak pressure of your blaster. You can do that by using a weaker spring, or pumping up your air blaster less. This approach sucks because you lose range.
  • Use a longer barrel, so that the pressure inside the barrel (and dart stem) is lower when it exits the barrel. On a high volume air blaster, this sometimes requires you to use an impractically long barrel. On this pistol, you maybe only need a few more inches (maybe just 2-4 more inches?).
  • Use half-length darts, which will clear the barrel sooner and so there won't be as long of a section of the darts with a pressure gradient acting to split them. It's still possible for these to split, though.
  • Use solid foam darts. This is the most straight-forward solution, but most darts you can buy have hollow cores, so this is usually a no-go.

In Topic: Dart foam is cracking, but the heads are not blowing off.... Help plea

25 April 2019 - 07:39 PM

Are they getting cut by something in the mechanism?

Foam splitting is typically caused by high peak pressures in the barrel, but I don't think you would necessarily see that in your setup. Possibly the barrel is too tight?