17 replies to this topic

[ShadowTank]

The new version of the Modified RP 20 I am working on, I plan to have 4 circular rows of darts, fired by two air cylinders. Only one will advance the actual ammo clip. I am using CO2 so I have plenty of pressure to supply both. I have had great success using CO2 with what I call the ST-2 which is the RP20 modified to use CO2.

I am custom making the ammo clip. My question is, if I wanted only one row to fire at a time, I would have to have the barrels in the ammo clip offset by 1/4 instead of 1/2 a barrel. Which means when one of the cylinders fire, they would be firing into an obstruction. Would this cause the cylinder to become damaged becaue the CO2 has no where to go. the only other option I can think of is not to use the cyliner, and just run a line to the other two holes and when pressure is released by the trigger, it will flow and where there is an opening for the barrel, it will release the CO2. Sure there will be some leakage, but only when I'm firing.

Any thoughts other than I'm nuts for doing this?

Shadow Tank

[General Cole]

Yeah. I tried that. But I had a piston pushing darts back into the turret. It REALLY complicated. Be warned.

[Maeric]

Wow thats fairly well thought out for just a concept thread... Hope it work, because then it would be the first homemade automatic... or well... you get my point, and its 10:00 and I cant think.


EDIT: HA! Its 9:20 and i can think just a little bit better, and CO2!?!?!?! Have you seen what the temperature of decompressed Co2 does to plastic? It would crack your cylinder! It wont work. Very well anyway.

Edited by Maeric, 13 September 2007 - 08:22 PM.

[ShadowTank]

I don't understand how that could happen.

What i'm talking about is the cylinder that advances the barrel/turret and releases the air into the barrel chamber once it has advanced the barrel/turrent to the next position. I want to stack one on top of the other, so I can have 4 rows instead of the two that now exist. The design of the barrels/turret would be similar to the original design, only bigger. THe darts would be in the barrell just like the original RP 20.

ShadowTank

Yeah. I tried that. But I had a piston pushing darts back into the turret. It REALLY complicated. Be warned.

Yeah. What i'm conceiving is basically a "Tommy Gun" Design. The other issue I am trying to work out in the design is how to attach a "beam" of some kind accross the top, to extend past the barrell/turrent assembly so I can add a front support for the barrell/turret assemblyt AND a front handle, and a barrell to place infront of the assembly.

Shadow Tank

Wow thats fairly well thought out for just a concept thread... Hope it work, because then it would be the first homemade automatic... or well... you get my point, and its 10:00 and I cant think.

[CaptainSlug]

Too complicated and not likely to work.

[King Of Butt Land]

Slug says it how it is. And besides, who will want to nerf with you when your using such an unnecessarily large weapon?

-Butt

[Z-man12]

Slug says it how it is. And besides, who will want to nerf with you when your using such an unnecessarily large weapon?

While I agree with your first statment.

I disagree with the second one. I love BIG guns. Wait tell I finaly get done with my curent project its a little on the large size.... If you call the long shot with front gun large, its about that long.

[ShadowTank]

There is a reason I am called ShadowTank. With the group I belong to who I particpate in Tactical action with, my character is a Weapons Design & Bulider Specialist. People love to play with me and my advanced weapons, cuz, at some point, I do run out of ammo, and usually get killed while reloading, it is the one downside to such a weapon.

Although my weapons are advanced, my health is not. I can not run, or even walk faat without having heart/breathing problems. So I am semi-stationary most of the time. So my "targets" can quickly move and get out of range if they see me before I fire. So this weapon "levels" the playing field for me.

I have a modified RP20 using the standard Turret/Barrels, using a mod I found online that allows you to interchange turret/barrels. I have 4 spare ones plus the one mounted on the Gun, and it is not enough. It still has it's deficiencies.

I also modified it for CO2, and was told in the past it would be too complicated, but I was successful at it. I'm just trying to get as much information as possible from those who might have tried something like this, or knows how these guns work mechanically to get more input and to determine if my understanding of the mechanics are correct.


I have managed to design, thus far, a way to mount the two cylinders on top of one another. I discovered there are holes int he back of the piston/cylinder assembly so there is no vaccum created for the space behind the o-ring in the middle of the assembly. I can trim/cut the cylinder in the back to make it 1" in dia, so the spacing for the holes in the Turret/Barrel assmembly will line up to a .5" spacing for all 4 barrels.

Does anyone have any thoughts on the possible "backflow" issue with the co2 firing into the turret/barrel assembly with no open holes? Is the very tiny space between the turret and cylinder/piston enough for the CO2 to escape without pushing the piston back causing damage?

OR, is it possible, that it won't effect it, it might stay "in" the forward chamber if it can't all "Escappe" and by the time it is about to fire, the turret/barrel will be "open" and start to fire?

Any information that can be provided would be greatly appreciated.

ShadowTank

[KBarker]

I respect your thought process on this and it may well be possible for you to build, but you can get the same net result by combining two conventional RF20s like FA_24 did. Or you could do what I do and just dual-wield the weapons. You can still lay down 40 rounds in ~3 seconds.

[CaptainSlug]

Might I recommend considering this instead: http://nerfhaven.com...?showtopic=7433

Much easer to reload, more sensible/usable rate of fire, and far less complicated.

[Borgadin]

If You build it you should not let the CO2 directly into the System, if you want the Blaster to last you would need a "heating" chamber because as soon as the CO2 leaves its tank it will expand and cool the surrounding matter, which is the reason why CO2 is usually a bad idea in Plastics. The lower the Temperature the higher the probability of the Plastic shattering.The best way to get around this would be to build a series of 2 tanks, 1 metal one for the heating of the CO2 followed by the second plastic Air tank which will hold the heated CO2 ready to be used.

[CaptainSlug]

I think you meant expansion chamber.
And yes CO2 is very hard on plastics over time. It's best to stick with HPA.

Edited by CaptainSlug, 11 September 2007 - 07:49 PM.

[the essence of death]

First off I'm gonna agree with everyone else, co2 is a BAD idea with plastics without an expansion chamber. However, im not gonna encourage you with this but im posting it rather to save your nerf gun from shattering in your hands, heres a link to a couple expansion chambers from the website I get most of my paintball gear from, http://www.specialop....asp?CAT=111203
Getting any of those should suffice as far as having an expansion chamber and I belive that most of them can be connected directly to the tank and then to your weapon. Just remember that hpa would be a better idea from now on, you can get it in the same pressures, and its usually cheaper to fill and lasts longer between fills, its also more comonly availible.

[ShadowTank]

I have been using CO2 for 4 years now, with great success now, though in the beginning there were problems. You are correct about Plastics not liking CO2. During the first 3 years of use, I had constant problems with the plastic line from the CO2 pressure regulator I was using to the trigger/valve assembly cracking and bursting. I then looked into why this was happening and discovered the CO2/Plastic issue, and replaced the line from the regulator to the trigger/valve with Steel lines. I use a 20oz Tank with a hose line. By the time it reaches the Trigger/valve it appears to have "expanded" enough, because since replacing the line as I described, I have had no issues whatsoever.

I do apprecaite the valid concerns and warnings, and they are appreciated. However, by shear experience, I have now able to overcome these issues, and it performs with excellene.

ShadowTank

[Pineapple]

If you have been successful with CO2 in your Nerf blasters for 4 years, I don't understand why you're coming to a forum where most of us don't even bother with CO2 in our blasters.


CaptainSlug, who by PROOF and WORKING EXAMPLES is probably one of our best authorities on compressed gases, lent his opinion, "too complicated". If that doesn't work for you, go and rattle on, but most of us won't be overly concerned (except maybe the newbies who will be impressed by the technological theory and concepts and stuff.)


There's a saying that goes around discussion forums. This thread is worthless without pictures.

If you have that much experience and advanced knowledge of a CO2 powered, fully automatic, high capacity Nerf blaster, you certainly must have a digital camera somewhere.




I'm wondering why I'm coming to the forums less and less now.

[ShadowTank]

I am asking questions concerning the mechanics of the Rapid Fire 20, not how to convert a nerf gun to CO2. I only mentioned i'm using CO2 because the pressure will be higher than when using tradtional "Hand-pumped" pressure which would most likely not be sufficient to supply air to two cylinders/pistons.

Since this Forum discusses several different kind of mods that are possible with nerf guns, I was presuming that someone would have an answer to my specific question concerning using two cylinders/pistons at the same time and what speciofic complications might there be.

One person already replied indicating they tried it, but the issue they described I'm not sure how that would occur and I asked for clarification.

I was only asking a specific mechanical quesiotn about the RP20, not about how should I go about to making all of the modications needed to accomplish the goal. I realize I am in unchartered territory here, so there is going to be risk, and much trial and error that I will have to do on my own. Especially when it comes to using CO2.

I did not and do not intend or mean to insult or otherwise proclaim anyone being wrong in terms of what they have said, including warnings about using particular materials (such as CO2) I only speak from what I have experienced and as long as you upgrade critical parts, including the air lines, i have found Nerf Guns can be upgraded to CO2 successfully, but that isn't the purpose for me coming on here and asking the questoins I have. I have observed for myself the mechanical operation of an unmodified Rapid Fire 20, and I believe my understanding on how they work is correct, however, I always found it is better to ask others who also may have knowledge on how they work to confirm or not that understanding.

And here are two pics, one assembled, the other showing the internal parts for the successful ST-2 that I have been using for over 4 years.







Enjoy!

Shadow Tank

If you have been successful with CO2 in your Nerf blasters for 4 years, I don't understand why you're coming to a forum where most of us don't even bother with CO2 in our blasters.


CaptainSlug, who by PROOF and WORKING EXAMPLES is probably one of our best authorities on compressed gases, lent his opinion, "too complicated". If that doesn't work for you, go and rattle on, but most of us won't be overly concerned (except maybe the newbies who will be impressed by the technological theory and concepts and stuff.)


There's a saying that goes around discussion forums. This thread is worthless without pictures.

If you have that much experience and advanced knowledge of a CO2 powered, fully automatic, high capacity Nerf blaster, you certainly must have a digital camera somewhere.




I'm wondering why I'm coming to the forums less and less now.

Edited by ShadowTank, 12 September 2007 - 08:46 PM.

[Pineapple]

Lookin' good, bro.

No offenses intended, and if you took it at that, my apologies.


You can understand our skepticism when we get thread after thread of "I did ______________" (fill in the blank), with no pictures nor any types of proof other than words on a page. It gets tiring after several dozen of those.


Basic forum rule (according to Piney); discussion threads about what you have, worked on, accomplished, etc., are basically worth little without pictoral record of what one is doing or what one has. You have chosen to produce pictures of your work, hence you get mucho respect points (from me, at least.)

But why you'd want to do the "double" tank is beyond me....with that rig you've got, you be throwin' some serious dart down the way. But....I can see that you have the ability to challenge yourself with such a mechanically complex monster. Good luck, dude.


-Piney-

[ShadowTank]

The reason is, with the CO2, and such a high rate of fire, I empty the mag in less than 2 seconds. Even with the "quick change" mod I did (a mod design by Falcon, I believe, except I super glued the gray piece of the gun frame to each turret, and I hold it in place with rubber bands - as shown, vs what he did which was make it a "flap" attached to the actual gun), and having spare turrets/barrel mags, it was not enough. I am still getting killed. If I was more mobile than it would be sufficient. But I can't move very fast at all, even to walk can be difficult with being fatigued and tired due to health reasons. So, I need to develop a gun with more firepower. The ST-3, the current RP20 Mod I'm not sure if I should even call it a mod. It's more I'm using several parts from the RP20 to make the ST-3.

Here are some current "sketches/plans" for the current design.











As of tonight, I have tested without being in any frame, firing two pistons from one (CO2) source, and it worked!

I have also modified the RP20 Gun frameto the size I need. Basically I chopped off the top pieces along the top edge where the top of the Bladder used to be and on the front so it is one "smooth" surface to mount to the steel plate that you see in the first drawing.

My biggest stumbling block is to find someone who has access to a CNC Mill to make the plates for the drum. To have it done at a business will cost several hundred dollars, which is a bit over my budget. This thing has already cost over $100 in parts, but when it is all together, it will be well worth the effort. :-D


Shadow Tank

Lookin' good, bro.

<SNIP>

But why you'd want to do the "double" tank is beyond me....with that rig you've got, you be throwin' some serious dart down the way. But....I can see that you have the ability to challenge yourself with such a mechanically complex monster. Good luck, dude.


-Piney-