4 replies to this topic

[M4573R]

After learning about plungers and finding some compression springs, my second attempt at a SNAP is much more compact and powerful.
I built this with a 1" PVC body instead of 1 1/4" and used a bolt for the plunger rod instead of thick-walled PVC.

The plunger:
A 6" 1/4-20 bolt and two small compression springs from Ace (don't remember which product #) I then have a sliver of electrical-tape-wrapped PVC for my o-ring sandwiched between a couple washers. I use a third washer, spaced by a nut, for my catch. It has a hair over a 2" draw. At first my plunger head was made of 1/2" CPVC fittings, which are smaller in diameter than the washers. I was able to suction-feed darts with it. However because I couldn't make a catch with it, I switched over to the washers. They aren't perfectly straight, and I think them rubbing on the inside of the PVC is ruining my perfect seal, but I'm not sure.




I used electrical tape around the end of the bolt to get rid of the slack and prevent the plunger head from extending too far into the body.
It's important to note: I had to drill a bunch of holes in the end-cap because the seal was too good and air couldn't fill the plunger tube as fast as it was pushing it out. Without them, it wouldn't function.




The trigger:
I used the same trigger design as my first homemade: A clothespin and a shelf peg.






The barrel:
1/2" CPVC barrel wrapped in electrical tape to fit inside a 1"->1/2" reducer. Reinforced with hot glue.




The final product:






Comparison with my first homemade:




Summary:
Tools used: PVC cutter, drill, hot-glue
Relative difficulty: 0.0. A few holes were drilled, but other than that it was just cut-and-assemble.
Range: ~50 ft flat with snug darts.
Cost: Under 10 dollars.
What I learned: Having the washers with a diameter almost exactly the same as the PVC's inner diameter causes problems if they aren't perfectly straight. My PVC ring under the o-ring isn't straight, so the washers have a slight tilt and can rub. Either I'll try to use smaller washers, or find a silicon spacer to use instead of PVC so that I can guarantee it is straight.

[spencerak]

I like this a lot more than your first one, but why not make a regular snapbow? I made one with Ace #49 springs as oppose to the [k26] and it works quite well white it still uses locally available parts. You could also use the springs that come in packs of two(with two other, mostly useless springs) for a snapbow

[Xellah]

If you want to learn more about building off of the SNAP design, there's no need to re-invent the wheel through trial and error. Here are some very good write-ups on several variants of the SNAP design. Alternatively, you can also read through any/all of Carbon's homemades in the Homemade directory.

Snakerbot's Shortened PumpSNAP

Nerfomania's PumpSNAP

Rork's SNAPbow

Beaver's PumpSNAP

Also, a semi-old community SNAP thread that has some tips/tricks:

Community SNAP thread

[M4573R]

'Xellah', on 29 Apr 2012 - 10:18 PM, said:

If you want to learn more about building off of the SNAP design, there's no need to re-invent the wheel through trial and error. Here are some very good write-ups on several variants of the SNAP design. Alternatively, you can also read through any/all of Carbon's homemades in the Homemade directory.

True, I just find a lot of these are a bit overkill for what I'm looking to do. I will certainly be taking from these once I "graduate." Though I find starting from the ground up lets me discover reasons for doing things certain ways that may be taken for granted by other people.

Edited by M4573R, 29 April 2012 - 05:48 PM.

[Jilliop]

Are you aware of what a coupler is? There is no need to wrap CPVC in electrical tape and hot glue it into a reducer. If you take 1/2" PVC and sand the inside lip a bit (I use a de-burring tool but sandpaper or a file will work) you can hammer in 1/2" CPVC for an air-tight friction fit that will coupler into your reducer for a barrel. And you can take it out if you want. And it looks better.