TulipMama

So can we have some pictures of a prototype/finished product, or have you not made a working physical design yet?
Also, could a stock be attached from the bottom and top of the handle?

 

Hello again Silly,

 

I haven't started the build yet, I wanted to make sure that my design had any merit before I spent any resources on supplies and construction. I'll probably start ordering parts later on this week with build and, hopefully, functional testing info to follow.

 

As for the addition of the stock, it's something I intend to incorporate later on as well, and should be pretty easy to do. Without changing the internals at all, and just the addition of the stock, a longer barrel and/or pump slide, this thing can be changed to a more rifle or shotgun style blaster. With some length alterations to the body, spring, plunger and bolt, you could make the body more length appropriate for those styles as well. 

 

 

Edit: Hi, I've decided to try and get my hands on a piece of 1/2" Schedule 80 pipe, which has a nominal ID of 0.54" which is much, much closer to the 0.511" of the nerf dart without any modifications. 

 
PS What's a pneumatic tube liner?

I'm using pneumatic tube as a liner for the pvc pipe. Pneumatic tube is used in air control systems and air tools, usually made from nylon or polyethylene. Imperial sizes are based on the ID, so a 1/2" tube has a 0.5 ID and a .625 OD.

Question for tulip: would/does the current iteration of the design work with 16,25,and 35 dart drums?

 

Hello Silly, to be fully honest, I couldn't confirm that to be the case, as Stacy was designed to work with a standard nerf Magazine. If drums have the same external dimensions for their connection and dart retention clips, then there shouldn't be any issue with using one. 

 

 

Thanks to Mr. Jwasko, Mr. Meaker and Cpt. Slug's suggestions and comments, I've made some significant changes to the design again, and this time I think I may have a winner, though I am, as always, very open to suggestions. 

 

Stacy R3

 

 

In this iteration, I've removed the single action nature of the bolt/plunger, instead opting to have the bolt pushed forward by the wielder in order to seat the round. The plunger rod and bolt are both made from 3/8" PEX, the body is a more traditional 1-1/4" pvc, and the barrel/breach is made from 1/2" pvc with a 1/2" pneumatic tube liner. The pneumatic tube should give me the tighter barrel diameter that I need to fire these darts more efficiently, and it can pretty easily be opened up by a millimeter or two if need be. The connector screw is used as a cocking handle, pulling back the plunger and bolt simultaneously, the groove in the bolt allows it to move without interfering with the rainbow catch screw, and the groove in the plunger allows the connector screw to move forward freely to allow the bolt to seat the dart. The bolt head has an O-ring on it to seal in with the pneumatic tube in the barrel, and a screw/nut to push the dart forward without crumpling the foam, and moves the back of the dart forward of the hole connecting the plunger body & barrel. The plunger head is a rubber washer squeezed between two flat washers, and I have a long screw going down the length of the plunger for added support, I'm hoping that the rainbow catch will work on the nuts on this screw instead of putting all of the spring force on the plastic PEX.

 

The only thing I'm not feeling 100% about on this design in the 3/8" PEX being used as the plunger rod, because it is relatively soft and I feel like it will get torn apart by repeat use, particularly at the connector screw and the rainbow catch areas. The addition of the nuts on the plunger to catch on the rainbow catch are my attempt to help mitigate wear at that point, but I honestly don't know if it's worth the effort. Has anybody else tried something similar? What was the life-span of your part?

 

Thank you for your time and considerations

If I understand your R2 design correctly you are using a spring to compress air via a piston/plunger, and then release it all at once the bolt has closed the breech? That's really cool, interesting, and some food for thought.

 

But I don't think you actually need to do something so precise as all that. You could instead have the bolt slide forward immediately after priming. One way to do this would be to cut a slot in the plunger rod like in the Tornadobow. So you would pull back both the bolt and the plunger, then when you let go the bolt is slid forward by a light return spring.

 

Also if you are worried about the bolt being pushed back by air pressure during firing (like in Boltsniper's FAR) you could have the trigger interface with it just before it releases the catch. When you release the trigger, the bolt will be free to be pulled backwards along with the plunger.

 

Oh, and since the dart isn't going into the bolt you shouldn't need the "half pipe" section of the bolt. You'd be better off with a cylinder or a cone at the front to simply push the dart forward into the barrel. You'll need to use a tighter barrel than 1/2" PVC by the way (you are using micro darts/elites right?)

 

 

I had thought of doing exactly that, putting a spring just forward of the trigger inside the bolt and securing it with a screw so that when released, the bolt would slide forward and seat the dart while the plunger arm remained secure until firing. The reason I didn't pursue it was because I didn't trust a weaker spring to be able to force its' way through the mag, overcome all that friction and pick up a dart. I have a Retaliator and I have to apply considerable force to push the action forward, I don't feel like a weaker spring would be able to overcome that force reliably. Not to mention the added cost of the spring, which is already the most expensive part of this build. I may put a slot in the plunger arm and manually push the bolt closed, which should actually improve the spring efficiency for firing as it doesn't have to overcome all that friction from seating the dart, but I'll leave that as something to test after trying this single action plunger/bolt hybrid. I can always cut the slot afterward, but I am VERY curious to see if this works at all.

 

Just a quick question on the spring by the way. In this model I'm using a [k26] spring from Mcmaster cut to 4.75" (I realize I could get away with 5.5", but I'm being conservative), which in and of itself is fairly cheap (a pkg of 5, 11" springs for $12-ish) but the shipping is literally more expensive than the actual spring. Is that just the unfortunate truth of getting this spring, or is there a more cost effective means of getting one? Is there an analogous spring that's less expensive to acquire?

 

Anyway, back to Mr. Jwasko's points, as for the bolt being pushed back, I actually hadn't even considered that a possibility. With the current design, I doubt the air released would be able to push the bolt back just based on the spring keeping it forward, but if I were to manually push the bolt forward, I would have to do something. A secondary catch that engages when the trigger is pulled if a fantastic idea, and I'll definitely keep it in mind should I go that route.

 

The 'half pipe' of the bolt is actually serving several functions in this design, and while I would love to be rid of the damnable thing (not looking forward to cutting that) its utility outweighs its annoyances. As it stands, it acts as a 'guide' between the two sections of 1/2" pipe that make up the barrel and breach, cutting a 1/2" pipe that would accommodate the mag would be even more annoying and basically have a 1/4" 'sliver' running between the two pieces. Secondly, it's a sort of secondary securing system for the mag since a 5/8" OD fits very snuggly inside that dart retainer at the top, and the mag will 'snap' over the edges of a 5/8" dowel without issue. It makes the mag harder to remove for reloading, but not too hard in my opinion. Lastly, it makes the 1/2" barrel a little 'tighter' since, as you say, a 1/2" pvc pipe is too loose to house an elite dart.

 

I don't have any better options for a barrel though since the dart is just a little over 1/2" and there is no PEX, CPVC or PVC pipes, or fittings that would have a tighter ID. Right now I'm sort of stuck on that. If I could make my own darts, I'd just use the PEX bolt and scoop them right into a matching barrel. The closest thing I can think to do is take the other half of the 'half pipe' part of my bolt and try to sand down the ID so that I can place it in the barrel to shore up the ID difference. Any other options for a barrel with an ID just over 1/2"?

 

EDIT:

I completely forgot about 5/8" PEX, which has a 0.584" ID, where the Elite dart has a 0.511" OD, so they are much closer. There's still roughly 2mm clearance, which is quite a bit, but I might be able to make that up with a duct tape liner?

 

Woah, the bolt and plunger release at the same time? Am I reading that right?

 

I'm not sure that's a good idea. Adding a second catch and a return spring on the bolt would do it as well and wouldn't require your strokes to line up perfectly every time.

 

What size plunger tube are you using? A dash-216 O-ring fits perfectly in 1-1/4" Sch. 40 PVC, and the Mark-8 has instructions for a rubber washer head in the same PT.

 

Ya, I'm really curious to see if this single action bolt/plunger release works reliably, if at all. I'm a little shy to go out and get the parts without some feed back on things that I'm missing since at this point I've already wasted some materials and time on a design that doesn't work, and I've basically thrown out my old design without even trying to build it. 

 

I'm using 1" PVC for the main plunger body, which is honestly why I'm having such a hard time finding a rubber washer that'll do the job. 1" OD washers are actually a bit undersized on 1" PVC which measures in at 1.05" roughly.