12 replies to this topic

[TantumBull]

Basically, it's an NF with a homemade plunger set-up. The plunger tube is the pump tube from some ancient off brand super soaker. The plunger head is the pump head from said super soaker. The plunger is made from three layers of 1/8" polycarb super glued together. The spring is a [k26] (plusbow spring). The plunger tube is a tiny bit thinner than that of an NF (maybe a 1/15th of an inch? maybe 1/10th) but the gun has twice as much draw. The a 1/2" coupler epoxied and bolted to the plunger tube. The plunger tube is held to the shell by bolted on PVC segments. Onto some pics.

The plunger rod minus handle:


Here's a better view of the catch:


Here's the plunger tube assembly, with e-tape to center it in the shell:


Here's the plunger assembly with the handle (rod through hole with e-tape on ends):


Final internals pic (that last bit of e-tape is there on the end to constrain the triangle that will be apparent in a sec):


Here it is, unprimed and assembled:

Here you can see the triangle that is formed between the PVC segments, the PT, and the shell. Since the plunger tube will want to slant down from the slamming of the plunger and how the PVC constrains it, I needed the e-tape to prevent that. The PVC over the slits in the shell was originally where the stabilizers were going to go, until I realized that they would have made the PT slanted up. I'm going to be replacing the PVC segments with a poly carb extension of the shell once I get my hands on some.

Here it is primed:


View down the PT:


What do ya guys think?

[Renegademilitia15]

Dang, that looks hecka beastly. Have you range tested it yet? If so, how much range are you getting?

[TantumBull]

Dang, that looks hecka beastly. Have you range tested it yet? If so, how much range are you getting?

I just range tested and I'm a bit disappointed. With a 5 1/2" fish store PETG barrel (9/16 OD, 1/2 ID) and a perfectly perfect seal, its hitting 65. And my normal NF hits 60 with a barrel with the same ID and is 3" long. Something's wrong here.

Edited by TantumBull, 25 July 2009 - 02:39 PM.

[Soothsayer]

Try a longer barrel. Some times we underestimate the power of our blasters and give it a shorter barrel than it should have, and it dampens the range.

[PointBlank]

Very nice, I like how it still uses the regular NF catch mech.

[TantumBull]

Try a longer barrel. Some times we underestimate the power of our blasters and give it a shorter barrel than it should have, and it dampens the range.

Yeah, thanks, I just ried that. My results are below.

Very nice, I like how it still uses the regular NF catch mech.

Thanks.

So, I tested it out with about 7.25 inches of CPVC and its hitting 75 to 80. Not bad for a pistol-ish gun.

[minsc]

Analogkid's Daedalus

As for the range, its sounds plenty fine, but if you still want more you can:
a) increase the plunger volume, a la the link above.
decrease the mass of the plunger. All that brass, pvc, polycarbonate and putty may be strong, but it is also very heavy.

Also, if you didn't minimize it that much, you wouldn't need as much reinforcement.

edit: I just read that you used a random pump, not pvc pipe like I thought. Nice job being resourceful.

Edited by minsc, 25 July 2009 - 08:50 PM.

[Soothsayer]

Also, try a dog bone CPVC barrel if you can.

[analogkid]

Very nice, I like how it still uses the regular NF catch mech.

Yeah the NF catch mech is a beast, I have never had one break on me, and I've done some stupid shit to nitefinders.

Anytime you make the plunger tube longer, you're going to need a longer barrel because it takes more time for the plunger head to travel the distance of the tube. As far as decreasing mass goes, if you're interested in doing that, I would get some 3/8" square nylon from McMaster. I believe that it is lighter and should also be easier to drill and tap. Regardless, that's pretty sweet.

[TantumBull]

Analogkid's Daedalus

As for the range, its sounds plenty fine, but if you still want more you can:
a) increase the plunger volume, a la the link above.
decrease the mass of the plunger. All that brass, pvc, polycarbonate and putty may be strong, but it is also very heavy.

Also, if you didn't minimize it that much, you wouldn't need as much reinforcement.

edit: I just read that you used a random pump, not pvc pipe like I thought. Nice job being resourceful.

Thanks for the suggestions and compliments. But I'm a little confused about what you mean about needing less reinforcements if I didn't minimize it as much. There would still need to be something to retain the plunger tube. But anyways, I did this to an already minimized shell I had laying around.

Also, try a dog bone CPVC barrel if you can.

Right now I have a CPVC coupler nested in the PVC one. I sanded it down first so I can still remove it with pliars if I need to.

Very nice, I like how it still uses the regular NF catch mech.

Yeah the NF catch mech is a beast, I have never had one break on me, and I've done some stupid shit to nitefinders.

Anytime you make the plunger tube longer, you're going to need a longer barrel because it takes more time for the plunger head to travel the distance of the tube. As far as decreasing mass goes, if you're interested in doing that, I would get some 3/8" square nylon from McMaster. I believe that it is lighter and should also be easier to drill and tap. Regardless, that's pretty sweet.

Thank you. I'll definately consider the nylon if I make another version of this.

[Soothsayer]

What did you get better results with, PETG or CPVC?

[TantumBull]

What did you get better results with, PETG or CPVC?

CPVC, because the 1/2" ID PETG wasn't long enough and I don't have anymore at the moment. CPVC is also tighter. However, right now I'm using some thinner walled CPVC for my red darts (a little to big for normal CPVC). I might try to get my hands on some more of the PETG, because the CPVC has been used and is a little bumpy on the inside from water (found this piece at a dump, only piece of CPVC I've ever found that have a wider ID than .48).

Edited by TantumBull, 26 July 2009 - 11:53 PM.

[TantumBull]

Just did some range tests, and I was very dissapointed. I think the reason the ranges dropped are because of the heat (high nineties), but I may be wrong, because my regular NF shoots like the exact same distance minus a couple feet.

8" to 8-1/2" CPVC barrel. Tight dart fit, needs twisting.

Slug weights:
62, 70, 74, 78, 65
Avg--->70

3/0 weights:
67, 69, 69, 65
Avg--->68

I'm gonna try out a longer barrel later. At this point I'm about ready to drop the project if my normal NF shoots just as far. That's what will happen if ranges don't improve with a longer barrel (already tried shorter).

Edited by TantumBull, 28 July 2009 - 10:35 PM.