This will take a fair amount of air to operate. I used an expanded 4b which was fine. Titans and the like would be great. I imagine it can be scaled down or up as I didn't put any math to this at all. It holds 50 1.3" darts (squished in up to the muzzle) and fires 30+ at good pressure out to 80'. At low pressure I get 15 darts at what seems like safe velocity.
I use a manifold inside the endcap which can be optional. I haven't tested this without the manifold to see if there is a performance difference. It does make building easier and produces a bit more durable absolver. A simple dart stop would work in it's place. It can be loaded by removing each barrel or by simply pushing 2-3 darts down each barrel and ramrodding them in. I am showing it fitted with a threaded 3/4" cpvc female coupler. It would work with other configs of course, but this fit my application. Thanks to Nerf Doctor for helping me finalize the coupler setup. Longer clips &/or barrels would work too. I'd like to try petg barrels on this for weight soon.
Materials:
1/2" conduit or pvc (4x 6 3/4" or longer)
1/2" cpvc (4x 8 1/2" or longer)
2x 1/2" cpvc couplers
1 1/2" pvc endcap
3/4" female coupler (or similar)
Thick acrylic sheet (or polycarb/similar)
Super glue (thin and gel) or Epoxy/Solvent weld
Tools:
Dremel w/drum sander/drill bits
drill bits/corded drill/drill press
files/needle files (nice but optional)
Coping saw
We'll start by making these sub assemblies. Coupler, endcap and clips. To prepare the coupler I chopped the front off to remove the slip fit section but kept the area behind the gasket. I had to file off a protrusion as well.
First I trimmed the 4, 1/2" conduit sections for the clips. I cut and flied them down to 6 3/4" but I wish I had left them 2" longer now. I glued 2 sections together by laying them on a flat surface and using a tiny drop of superglue near the ends to secure them temporarily. Glue 2 more sections together and then test them for true before gluing up the 4 in a square. If they are wonky just whomp them apart with a mallet. I dribbled thin superglue down the join of each clip and set it aside to dry a while. I then chopped my cpvc couplers in half & filed them flat carefully. I had to remove a little material from the side of each coupler in 2 places to get them to sit right.
Let's prepare the endcap for the coupler. I cheated and used a manufacturing mark in the bowl at the center (kinda) to start the hole for the coupler. We can adjust for straightness when we glue it up. I also chopped a bit off the front of the endcap for weight, less fitting work and better access later.
I went up through a few sizes to my 5/8" bit (largest I have). Obviously the coupler I am using is much bigger. Some "custom" fitting with a dremel will be needed.
I marked the progress needed from the inside. I show the coupler on the other side for illustration. It should be possible to eyeball & adjust this dang closer to centered as you open up the hole.
Eventually I could whomp the coupler in most of the way. We'll finish fitting it later, just remove the coupler for now.
Now let's fit the clips. I marker, dremeled and filed the ends of the clips that interfered with the endcap.
Here's how it should look from the outside when fitted.
I used thick acrylic for the manifold, but poly or pvc would be better here.
I held it up to the back of the clips and marked the areas to remove. I removed that material with drill bits, dremeling and files.
I super glued this onto the back of the clips. I wish I had used one more coat of glue now that I see this pic. I did need to dribble some thin superglue into that area after it cured.
I cut the barrel material, filed the edges square and chamfered both ends with the reaming tool on my tubing cutter. I chamfered one end a little less and called that the muzzle. Ok now we should have this:
At this point I dry fitted everything to adjust for straightness. Fine filing of the hole for the coupler accounted for some adjustment and I filed the flat area on the clips a bit to make up for some more. I used the blaster out of the shell at this point. If using threaded couplers tighten the female to it's final tightness (might have to clean & grease the threads) before lining stuff up.
I marked where things needed to go to line up and glued in the coupler with gel superglue. I allowed that to dry a while and re-tested the clip in the endcap for straightness with the tape marks. I then applied a bead of gel superglue to the back of the manifold and to the endcap liberally. I whomped the clip home and set it aside for a day to cure. I added some thin superglue down the endcap, around the clip area in 2 layers.
Here it is fitted to a helix 4b reshell.
I added a little tubing to spread the barrels horizontally.
Edited by iamthatcat, 07 May 2012 - 02:33 AM.
