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DJ Mashbot

Member Since 29 Jul 2008
Offline Last Active Oct 23 2009 10:05 PM

Topics I've Started

Ball Valve Breech

16 January 2009 - 09:06 PM

This project was largely inspired by this old thread on rotary breeches. I tried to make one out of a ball valve, and found that it's just too much of a pain because: 1) your stefan size is limited to the length that rotates inside the valve, and 2) getting it to seal nicely with a barrel is more trouble than it's worth. So, in order to alleviate both those issues, I decided to create a type of hinging breech out of a ball valve.

1" slip ball valve
Barrel (I used CPVC)

Plumber's Goop
Oral Syringe
Electrical Tape

First off, take your ball valve and rotate the opening roughly 45 degrees. The opening aligns with the handle, so line up your drill with that and drill a 3/8" hole.
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This should be large enough to wiggle a dremel in there to open it up just a bit more. If you really wanted, you could just drill a 1/2" hole to start, I could not so I used a dremel to get me there. Make sure to keep the hole centered vertically and at least large enough for your darts to fit through.

Now, either drill through the center of the valve or flip the breech over to repeat this process on the opposite side. This time, make sure the hole is large enough for your barrel to fit through.
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Next, use your dremel to grind out a channel down this side. It does not need to be perfectly straight, but it must be wider than your barrel, as it will need to swing through to function.
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Wrap electrical tape around your barrel to fit the inside of the ball valve. Leave a small gap (maybe 1/4") between the tape and the end of your barrel, as this is where your adhesive will go. Place the barrel and tape inside the ball valve, so that the end nearest the tape is not sticking out of the ball. This is a good time to test and make sure everything can rotate and the holes line up with the barrel, as gluing comes next.
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Using the oral syringe, apply Plumber's goop around the end of the barrel inside the valve. It is important that you not use too much, otherwise it can seal the ball to the PVC case.
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Let it all cure for a day or two, then you have a functioning hinge breech. The good thing about it is that it is easy to operate, easy to make, and easy to afford. Unfortunately, it does not lend itself well to any sort of clip system, and it is easier to do with a larger size ball valve, which means your blaster's air output needs to be larger than the typical 1/2" to accommodate it.

Different Hornet Models

11 January 2009 - 02:28 PM

I did a search, but could not really find anything about differences between Hornet models, though it seems that there is a general aversion to Hornets. I was wondering if there was a difference between the Red, Green (Hulk), and Blue/White (AS-6, it's on the TRU website) as far as internals go. I was considering picking one up but I didn't know if there was a better model that had fewer problems.

Homemade Rifle

02 January 2009 - 10:31 AM

As a detailed write-up would be extremely tedious, I'm just going to post pics and explain how it works.

The right side:
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The left side:
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For firing/priming the gun I used a backwards hose handle, because if triggered quickly it works well, and I find it easier to trigger when it's backwards. The hose handle is epoxied to a brass ball valve with a straight lever handle. That ball valve controls the air flow between the main air tank and the firing chamber, which is the black hose and the inside of the hose handle. So, in order to prime the firing tank, the hose handle is twisted counter-clockwise, then returned to it's original position to close off the main tank. I did this so that I wouldn't have to shift my grip around to re-prime the gun. Here's a close-up:
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For loading stefans, I wanted to try something experimental. I hadn't seen anyone do this before, so I wanted to see if it would work well. The barrel basically rear loads with a ball valve, with air entering just ahead of it. It is similar in principle to an RSCB clip, but with manual loading. I realize it doesn't have the high burst RoF that a RSCB clip has, but it can be easily loaded at a steady rate overall and you don't get misfires. Here's a close-up:
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My goal for the gun was to have decent power with a good RoF, without having to move my hands all around to work it. For the most part I feel I succeeded. Only the left hand has to move to load darts (and this movement is minimal), the power is a bit less than my modded BBBB (this is a guesstimate), and it gets maybe 5 shots before it really loses power (another guesstimate). It's cold out and I'm sick, so my range tests have been limited to a 30' length in my house, and that's what I'm basing my range/power loss ideas on. Questions/comments/flames?