Jump to content


Photo

Semi-auto 2k Prototype-its A Start

or an end?

294 replies to this topic

#226 Gene-ious

Gene-ious

    Member

  • Members
  • 38 posts

Posted 31 August 2004 - 11:45 PM

I want to make my 2k a semi-auto also, but i dont haev the time... school starting soon.. sorry to be kinda off topic, but does putting the PVC pipes give it a bigger air tank??
  • 0
<----Down to Earth Thinker

#227 THIRST

THIRST

    Member

  • Members
  • 1,099 posts

Posted 01 September 2004 - 05:29 AM

Much, much bigger, which is not always wanted since you need many more pumps to achieve the same pressure. Also, it would not be much more powerful than a regular 2k, since once the vulome is enough to propel several darts already(regular 2k), increasing the volume more is not going to help you much.

THIRST
  • 0
ko

#228 Vintage

Vintage

    Member

  • Members
  • 462 posts
  • Location:Minnesota

Posted 01 September 2004 - 09:46 AM

Thirst, after my vinyl tubes broke off, I tried epoxy. Last night after I had waited 24 hours, I tried the pump. Almost instantly the epoxy lost it's seal. When I checked it out, the epoxy just peeled right off. It turns out, my epoxy (I don't want to say all epoxy) doesn't stick to vinyl tubing. Bummer for me.

So, this morning I went back over everything, putting goop everywhere. I am hoping the extra goop will hold it on this time. I have three layers of bike tubing over the bladder, and just need the goop to cure. I should have a writeup soon after I find the outcome of the seal. That's one benefit to your lack of vinyl in your setup, Thirst.

~Vintage
  • 0
You can get much further with a kind word and a gun than you can with a kind word alone
~Al Capone

#229 david00790

david00790

    Member

  • Members
  • 138 posts

Posted 01 September 2004 - 10:11 AM

I did that same mod with a loser rifle like two years ago but nice try.
  • 0

#230 ompa

ompa

    Introductinator

  • Moderators
  • 2,368 posts

Posted 01 September 2004 - 10:34 AM

I did that same mod with a loser rifle like two years ago but nice try.


So... then if you did it so successfully, why don't you go ahead and show us? It's a thread to discuss ideas. So, tell us what you used, pictures, and whatever you may have regarding that project. Just telling us you "did it" isn't exactly a good contribution to this thread.

...Nice try? What the fuck is that supposed to mean?

~ompa
  • 0

#231 Vintage

Vintage

    Member

  • Members
  • 462 posts
  • Location:Minnesota

Posted 01 September 2004 - 10:35 AM

Edit: /\ /\ /\ Ompa beat me by a minute <_< /\ /\ /\

I did that same mod with a loser rifle like two years ago but nice try.

Dude, your point is? We are not here to brag. You can just leave your ego to the other threads and help us out here.

This thread is a group effort to make the AT2K a semi-auto weapon. Unless you have something to contribute (maybe pictures and a description of your "loser"), you really don't belong in this thread.

No one is claiming originality to the idea. That type of claim is stupid anyway. If you never documented your idea on the forums, you have no right to diss us.

Back on topic: I did some research and the reason the epoxy did not stick to the vinyl is due to the greasiness of the vinyl exterior. I should have thoroughly cleaned and sanded the tubing for the epoxy to stick. Oh well, I guess the goop will just have to work then.

~Vintage

Edited by Vintage, 01 September 2004 - 10:36 AM.

  • 0
You can get much further with a kind word and a gun than you can with a kind word alone
~Al Capone

#232 ompa

ompa

    Introductinator

  • Moderators
  • 2,368 posts

Posted 01 September 2004 - 10:37 AM

Eh, beat you to it Vintage! <_< Ah, I'm just kidding around.

You sand the tubing though, you comprimise some of the integrity of the tubing itself. If you're really worried about the connections, you COULD coat the nipple in goop, then slide the tubing on. Not too much goop of course, for obvious reasons.

~ompa
  • 0

#233 Vintage

Vintage

    Member

  • Members
  • 462 posts
  • Location:Minnesota

Posted 01 September 2004 - 10:40 AM

What I meant by "alot of goop" was the fact that I almost coated the entire tubing setup. I didn't build up a bunch of goop at the connections, I just made sure I spreaded the goop out alot, giving it more space to grip the vinyl.

~Vintage
  • 0
You can get much further with a kind word and a gun than you can with a kind word alone
~Al Capone

#234 ompa

ompa

    Introductinator

  • Moderators
  • 2,368 posts

Posted 01 September 2004 - 10:44 AM

so we can call the gun, "Da goop gun" now? Haha. Anyways, my apologies guys for not working on the gun much- I have no pvc left for the most part, no cpvc, or anything. Sorry. I'll get back on the leaks on mine over the weekend.. I'll be checking this thread daily though and see what I can input.

~ompa
  • 0

#235 cxwq

cxwq

    Member

  • Founders
  • 3,634 posts

Posted 01 September 2004 - 11:17 AM

I'd been planning to test these ideas myself and report back but time is a limiting factor so I'll share my thoughts here and perhaps someone can run with them.

Given that

d1 = sqrt( Flow / (.01749 * (P1/29.7) ) )

Where

d1: aperature diameter in micrometers
Flow: desired gas flow in cm^3/minute
P1: tank pressure in PSI

And assuming

deltaP/P1 > .5 (note: P2 = atmospheric pressure = 14.7PSI so our flow is fixed at the speed of sound)
T ~= 68 degrees F

We can calculate an aperature size tailored to a desired flow rate.

I don't have an at2k tank in front of me so I did some guestimate calculations using d=3cm and l=4cm (internal) and 70PSI secondary tank pressure. The flow target is a little tricky because you want to be able to fire relatively rapidly but you want minimal air loss. I picked 4 seconds as an adequate compromise for full pressure balance from secondary to primary tank.

sqrt( 424 / (.01749 * (70/29.7) ) ) = 101 micrometers = .1mm

Adjust to taste.
  • 0
<meta name="cxwq" content="mostly water">

#236 Vintage

Vintage

    Member

  • Members
  • 462 posts
  • Location:Minnesota

Posted 01 September 2004 - 11:29 AM

Hmmm.... I wonder if the crimp in my vinyl is restricting the airflow compareable to a tube of .1 mm diameter. For me, if the crimp is too tight, it takes 4 seconds for the pressure to equalize after a shot. Obviously that hurts the semi-autoness, so am using small sections of brass tubing to prevent the tubing from crimping too much.

Man I wish my memory card reader was working. I really need to go out and get another.

Edit: Why I was not satisfied with the 4 second transfer rate was because I let go of the trigger within the first second of firing. With the four second crimp, I lost about 1/4 of a shot's worth of air. With the way it is set up now, I lose more than a half of a shot, but the rof is enough to fire the turret in 6 seconds. These tests were done before I blew my tubing connections.

~Vintage

Edited by Vintage, 01 September 2004 - 11:33 AM.

  • 0
You can get much further with a kind word and a gun than you can with a kind word alone
~Al Capone

#237 THIRST

THIRST

    Member

  • Members
  • 1,099 posts

Posted 01 September 2004 - 05:50 PM

I did that same mod with a loser rifle like two years ago but nice try.

A loser rifle? Thats awfully generalized. Anyways, post some pics, show us how it works, and hopefully we can benefit from it.

Genious Cx. Not that I understood what it meant :lol: Actually, after rereading it several times through, it makes some sence.

Anyways, after redoing my first 2k, I plugged up the liquatron, and nside the liquatron path from the secondary airtank with goop, lots of goop. Then, I stuck a small zip tie, about 1mm thick. So now my airflow is bad enough for my gun to be able to fire more efficiently. With 50 pumps, I can get 5 shots off, and still have air in the tank. Though it doesnt seem like a difference, my previous version got 5 only if my finger was quick, and the 5th shot was always weak. In this version, I dont need a fast finger, just pull it, and let go, very easy to use, much more comfortable. I would take it over a bf anyday. It is much more air efficient, and since I BIC pen modded it, its got a hair trigger, so it is much easier to use.

That's one benefit to your lack of vinyl in your setup, Thirst.

Mmm, good point. Im gonna make another design still using the liquatron attachment, but more proffesionally regulated than my current design. Give me some time, I think if we put 2 inner tubes over the bladder, and have it similar to my attachment, it will work. Now I need to do a better regulating job. Muhc better. Like, a bit bigger than needle size. I think that I will be able to get more shots off, think about it. Its under more pressure, but less air is let out, so more shots, higher pressure. The large regulation will counter the effects of the bladder pushing the air out too fast, and I think it will effectivly raise the pressure to create more shots, more range. Thoughts?

THIRST

Edited by THIRST, 01 September 2004 - 05:52 PM.

  • 0
ko

#238 Vintage

Vintage

    Member

  • Members
  • 462 posts
  • Location:Minnesota

Posted 01 September 2004 - 07:27 PM

Actually, Thirst, adding innertubes raises the pressure which makes more air come out with each shot. You will get less shots for the same amount of pumps, but, you can pump it more to give it the same bladder inflation size. But I see your point in that less air from the bladder will escape with the shot.

The pin hole regulation will prevent too much extra air loss from the bladder, which will help give you more shots. I think this is why you were only getting 5 shots per pumping. Your restrictional area was too large. Even now, maybe your zip tie hole might not be working. Goop flexes and bends well, so the air pressure might be enlarging the hole when it is pumped.

~Vintage

Edited by Vintage, 01 September 2004 - 07:28 PM.

  • 0
You can get much further with a kind word and a gun than you can with a kind word alone
~Al Capone

#239 THIRST

THIRST

    Member

  • Members
  • 1,099 posts

Posted 01 September 2004 - 07:35 PM

Nonono, your missing the point, Im very happy about my regulation right now, and I think it has potential.

Actually, Thirst, adding innertubes raises the pressure which makes more air come out with each shot. You will get less shots for the same amount of pumps, but, you can pump it more to give it the same bladder inflation size. But I see your point in that less air from the bladder will escape with the shot.

Yes, I will have less shots, but ebcause of the pin hole regulation, it will come out faster, counterign the effects, but putting it under more pressure. Which is what I'm looking for.

Goop flexes and bends well, so the air pressure might be enlarging the hole when it is pumped.

Doubt it. I have used goop to secure some very sketchy places, including vinal attachment, and it was under more pressure. The rf20 vinal pops off from the goop because it's too much pressure for that connection, and the vinal. In a place such as inside the liquatron, the goop will hold under the pressure, and after 48 hours of drying, its nearly rock solid, and easily capable of handling the pressure. It has more support, and is more silid than vinal tubing clinging to a nipple, because theres nowhere else for it to go. Im confident, because I've seen it work. I'll test with it soem more when I get another 2k.

THIRST
  • 0
ko

#240 texmustache

texmustache

    Member

  • Members
  • 198 posts

Posted 01 September 2004 - 08:48 PM

I bit off topic (ha.) but...

Okay, write-up time.
Correct me on anything, post any questings, point out any mistakes. No pictures as of now...

I’m assuming you have:
1 Airtech 2000
1 rapid fire 20

Other materials:
Hose clamp
Clip ties/epoxy
Brass (9/16 or 17/32)

Step 1:
Disassemble both guns. You can scrap the RF20 case, but be sure to keep:
The both valves
The TUBING
The tubing connecters (the white and black things near the tubing connections)
The AIR BLADDER!

Disconnect all tube connecters (I’ll call them tube-screws) and take out all the tube.

Step 2:
Using pliers, unscrew the pump tube from the goo-gauge.
Keep the tube-screw (the black part clamping it)

Step 3:
PUMP TYPE
You have a few paths you can go to-

Step 3a:
Use the AT2K pump-
Pros: Faster pumps, VERY sturdily mounted
Cons: More pumps (50)

If you choose this, hold on to the AT2k tube screw, but attach the AT2k pump tube to the air bladder using a RF20 tube screw, which ever prong (the screw-ended parts for putting tube on) you want.

Step 3b:
Use the RF20 pump-
Pros: Less pumps (20)
Cons: Less sturdy mounting, takes up space, pumping is a bit harder

I’ll get to this and case mounting later.

Step 4:
AIR RELEASE METHOD
More paths…

Step 4a:
Using the main valve. (The valve with the two elbow prongs)
Pros: Easy to control air, super-fast ROF, no air loss from firing…
Cons: You must have quick fingers. I cannot stress this enough. Upon closing the valve AIR WILL COME OUT. But, you can easily let go and shoot quickly, wasting very little air.

Step 4b:
Using the slow release valve
Pros: No air loss from firing, no having to hit two valves.
Cons: Air takes time (<1 second) to fill valve, so air will be lost from firing.

If you choose either of the above methods, connect one tube from the air bladder prong to the valve, and another from the valve prong to the AT2k air chamber.

Or, you can read on.

Step 4c:
You can try crimping the tubing.
Pros & Cons are similar to the slow release valve.

If you choose this, just take one of your tubes, fold it like a z, and put a tie wrap around it.

Now your main firing setup is done:

I’d say use a turret for you’re barrels, as it has a high ROF and not much range loss.
You know the deal – pull of the existing barrels, glue on the brass: I’d recommend 4” barrels. The work the best, and logically, if 6” barrels are optimized for 90 feet, 4” barrels (2/3 as long) are optimized for 60 feet (2/3 as far).

You want to close up your case, letting the tubes out through the back, but you probably want to leave the blue clear part at the back off. Or, you can drill holes in it to allow the tubes in. Your choice.


Step 5:
Mounting the air bladder:
First things first, put your hose clamp over the white part with 2 prongs, then attach the black bladder, and tighten the clamp really, really, hard.


Step 5a:
You can choose to mount the bladder on top of the gun:
Pros: It’s easy =)
Cons: It gets in the way of aiming (not really)

If you choose this, just put two tie wraps close to the clamp, and put you’re tie wraps through the top of the Airtech2k case, on either side of the goo-gauge. Tighten it up really good.

Step 5b:
You can mount it on the back
Pros: You can use it as a stock; it doesn’t get in the way of aiming, Ompa says it's pretty secure.
Cons: It takes time to do.

If you choose this, dremel out the back part of the AT2k case, where the pump would come out. Then put the bladder in and tighten the case.

Step 6:
If you chose to use the RF20 pump:
Using a lot of cable ties, strap the pump on to the side of case. Put lots on the back of the pump to hold it securely, and others all over. Alternately, you can use epoxy/pvc glue to glue it to the side. Although you may want to dremel out the ridges that get in the way of the case’s natural curve.

Step 7: If you’re using a valve…
If you use the main valve, you want to mount it at the back (using clip ties all around), above the handle, tilted slightly upwards – this allows you to fire with your finger, and use you’re thumb to hit the valve by pressing downwards. The valve is hard to press, and you might want to insulate it with electrical tape, hot glue, FBR, or a combination of the three.

If you’re using the slow release valve, it doesn’t really matter where you mount it. Somewhere out of the way would be nice.

If you’re using crimped tubing, skip step 7.

Step 7.5
You need to attach the tube from your crimp/valve to the liquitron gauge, using the AT2k tube screw.

Step 8:
You’re done, right…?

Well, you might be. You can choose at this step whether or not to band the bladder:
Banding the bladder, whether with rubber bands (I used 50 smaller bands) or with bike tube (as THIRST of vintage) should add about 5-10 feet range. The debate rages on.

Otherwise, you are.
You should be aiming for-
Range 50-60 feet
ROF- Main valve – 4 shots, 2-3 seconds
- Slow release/crimp – 4 shots, 2-3 seconds (says Ompa)

My RF2000
Although it's changed quite a bit.
Posted Image

Edited by texmustache, 02 September 2004 - 11:34 AM.

  • 0

#241 BoltMasterZero

BoltMasterZero

    Member

  • Members
  • 70 posts

Posted 01 September 2004 - 08:49 PM

Tomorrow I'm going out to get an AT3000. I just found a Kohls near me that has 3 left. I am going to try out my CPVC tank expansion on it. Auto-rotation will be a plus, I will just have to pump between every shot.
  • 0

#242 ompa

ompa

    Introductinator

  • Moderators
  • 2,368 posts

Posted 01 September 2004 - 08:51 PM

My slow release valve has the same firing time.. I can get off all 4 shots in 2-3 seconds... And back placement is NOT unstable. If you do it right, it's actually quite stable. Hmph. :angry:

~ompa
  • 0

#243 THIRST

THIRST

    Member

  • Members
  • 1,099 posts

Posted 02 September 2004 - 05:31 AM

I dont know about your guns, but my tank fills up immediatly, and I can fire 4 shots as fast as you can pull the trigger. Does the crimp really hurt airflow that much? I'll have to try it.

Tex, beautiful writeup, very easy to follow. When you have pictures, PM it to me.

THIRST
  • 0
ko

#244 Vintage

Vintage

    Member

  • Members
  • 462 posts
  • Location:Minnesota

Posted 02 September 2004 - 10:02 AM

Yes! the goop holds!!! Man, what a nightmare. Well, now that the tubing is in place, I can start all my tests. I have three sections of innertube over the bladder.

First off, I tried my turret of 4" 9/16 brass. It sucked. It barely got 50 feet. Next I slid a 12" section of 17/32 brass into one of the turret barrels. I only have a 12" section right now, and I didn't feel like cutting it just yet. I used a thinner stefan and jammed the dart into the rear of the brass before I slid it down into the barrel. It immediately got 60 feet and perfect flight path (no fishtailing). I feel the solution is maybe a 4-6" barrel of 17/32 for my darts, or maybe a telescoped version with a few inches of 17/32 and 6 inches of 9/16.

I haven't tried the crayola yet, and there are many more things I should try. Right now, I get about 8 shots on 35 pumps. I am using a Z crimp like Tex said in his writeup. It fills the tank in exactly 1 second. If I were to add more bike tubing, it would probably fill quicker.

~Vintage
  • 0
You can get much further with a kind word and a gun than you can with a kind word alone
~Al Capone

#245 Hunter

Hunter

    Member

  • Members
  • 312 posts
  • Location:Vancouver, BC

Posted 02 September 2004 - 12:39 PM

As for AT2K barrel lengths, these are the most common.
Single Barreled: 7-8"
4 barrel turret: 6"

Obviously, the size of brass would totally depend on your darts. I use 4 9/16" K&S Brass barrels and I get ~80'.

Edited by Hunter, 02 September 2004 - 07:07 PM.

  • 0
Hunter
Organizer Vancouver Area Nerf Series

#246 cxwq

cxwq

    Member

  • Founders
  • 3,634 posts

Posted 03 September 2004 - 01:47 PM

My appologies if this has been addressed in this thread already.

Does anybody have experience using PVC cement to attach PVC directly to the tubing nipples at the rear of the goo-tube and the pump?
  • 0
<meta name="cxwq" content="mostly water">

#247 THIRST

THIRST

    Member

  • Members
  • 1,099 posts

Posted 03 September 2004 - 03:45 PM

Using PVC cement to bond pvc with plastic? Yeah, it works, its strong, and If you can get it airtight, it would work just as well as anything. The reason why I prefer not to use it for such applications is ebcause it is liquidy, and does not set very quickly, but if you can get around that, great.

THIRST
  • 0
ko

#248 Vintage

Vintage

    Member

  • Members
  • 462 posts
  • Location:Minnesota

Posted 03 September 2004 - 07:46 PM

Excuse me for asking, Cxwq, but what size PVC are you trying to cement to the nipple? My guess is that you plan on drilling a hole into a cap the size of the nipple for a good seal. If that is the case, it probably will work well.

~Vintage
  • 0
You can get much further with a kind word and a gun than you can with a kind word alone
~Al Capone

#249 cxwq

cxwq

    Member

  • Founders
  • 3,634 posts

Posted 03 September 2004 - 10:10 PM

That's more or less what I'm doing. I want to attach my secondary tank with no hoses to fail or get in the way and I noticed that a piece of PVC approximately the diameter of the smoked gray cylinder could extend from the rear of the goo tube, directly back (in place of the aforementioned cylinder) about 18" and act as a nice little stock. If I'm really careful where I drill the holes, I think I can get the pump nipple cemented directly into this piece as well - if not I'll use a ballpoint pen or something to bridge the gap. This would give me a solid, one-piece pump->secondary->goo tube->tank assembly. I'm experimenting with ways of reducing the flow from the secondary tank with this arrangement. Probably going to goop a tiny plastic bead with a hole drilled through it into the goo tube nipple.

The other advantage of this arrangement is (as you may have guessed by now) that I'm avoiding the whole CPS pressure issue by using a high pressure tank that will simply have 15-20 times the volume of the primary tank. Shouldn't see much pressure drop-off over the 6-shot capacity I'm planning. The down-side of course is the number of pumps required, but if I simply repump after firing my 6 shots, the secondary tank is already halfway pressurized so it will be reasonably efficient to recharge during battle.

I need to keep the top of the gun clear, and will be removing the top of the goo tube so that I can fit a RSCB barrel along the top of the gun. I want it to be close enough to actually dremel the 'handle' down into a cradle to physically support the barrel assembly.
  • 0
<meta name="cxwq" content="mostly water">

#250 THIRST

THIRST

    Member

  • Members
  • 1,099 posts

Posted 04 September 2004 - 11:52 AM

the 2k semi-auto Im working on now has a rf20 bladder, with regulation fo course, and it will be all solid, but right before the bladder will be a copper ball valve, so I can turn it off and sue the 2k as a regular 2k, or like a semi-auto, wit both tanks pressurized at the same time. If you do something like that, in the midst of a battle you can use it as a high-rof 2k when you dont have time to pump your secondary tank.

THIRST
  • 0
ko


0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users