Pressure chamber size?
Posted 22 October 2011 - 11:32 AM
Here is the current set up:
Posted 22 October 2011 - 03:39 PM
This post has been edited by BOSS9: 22 October 2011 - 03:43 PM
Posted 22 October 2011 - 09:31 PM
Yeah, I think the valve wasn't the problem, it was probably the 8 dollar foot pump I bought from Target a couple of years ago. I haven't the slightest idea of how to incorporate a small pump directly into my setup, but any forum suggestions would help . I do have a small dual-action bike pump on my Schwinn though. I will try that tomorrow and see if that works. I still am considering adding a massive air tank onto this thing and just have the electronic trigger glued onto a back hand grip on the tank, that way the night finder can be a front gun .
Posted 22 October 2011 - 09:34 PM
Posted 22 October 2011 - 09:40 PM
Bear in mind that the smaller the pump's diameter, the easier it'll be to reach those pressures, but it'll take more pumps to fill it up. Sounds obvious, but going to both a thinner pump and adding a larger air tank may increase the time between shots to something ridiculous. For reference, a Titan's air tank is around 320 mL and goes to 35 PSI when the pump isn't plugged. Around Sydney at least, even unplugged, singled Titans are banned. If you're just doing this for the fun of it, go right ahead, but if it's for use in an actual war you may not want to make it too powerful.
This post has been edited by 238232: 22 October 2011 - 09:40 PM
Posted 23 October 2011 - 07:23 PM
Yes I did try to fire it even after 15 or so pumps. There was still no pressure to speak of. I am still working on getting a smaller diameter pump integrated into the whole thing. Any thread suggestions on the matter would be appreciated.
Posted 23 October 2011 - 11:19 PM
So it fires, but does so with little pressure? And it definitely holds air? for "integrating a smaller diameter pump" you don't need to know anything special. Go to Ace or Menards and get some 1/4" OD 1/8" ID vinyl tubing, in the general plumbing section. Get any small, handheld bike pump- I personally have used this successfully- by just inserting the tubing into the schrader fitting and tightening the connector I have an airtight seal that has never failed me at any pressure. If that is not enough, some goop would solve the problem. sticking a pump on your gun could be as simple as zip ties and hot glue. connecting the tubing and tank? drill a 1/4" hole in the tank, slather with solvent weld, and insert tubing.
Posted 24 October 2011 - 03:46 PM
Considering how much primer and pvc cement I used on each connection, I would be really surprised if it wasn't airtight. I even used a ton of teflon tape on the pvc couplers. I have already immersed the tank in water and pumped it up to see if there were any bubbles coming from any of the connections.
Posted 26 October 2011 - 04:59 PM
Your pump is the truly critical piece in this problem. What kind of pump is it?
And one other question. When you pump and then fire, is it now easy to pump again? Because if it is still impossible, then no pressure is reaching the tank. You have something blocking your tubes most likely.
Posted 27 October 2011 - 09:05 AM
Posted 02 November 2011 - 02:48 PM
first off, your chamber is pretty small and the ball valve is a a very slow opening valve they generally only make loud swoosh or pop sounds if you have a large chamber, don't expect a nice pop sound or anything
second the amount volume of dead space between the barrel and the valve is large compared to your chamber volume, for testing purposes why don't you unscrew the barrel attached to the night finder and make a separate barrel that screws on directly to the valve, or duct tape it on whatever
third if you bought your pump for $8 it probably is terrible and useless
forth we can't judge your success based on the number of pumps you were able to make because different sized pumps can fill your chamber in fewer or more pumps, so make sure you tell us how big the pump is
fifth what barrel are you using? 1/2"pvc or a tight fitting barrel like 1/2"cpvc, 1/2" pvc is very loose and will only work well with high volume systems your better off with 1/2"cpvc or some other tight fitting barrel
Posted 03 November 2011 - 06:58 PM
Airgun pressure isn't constant like a springer's. When the spring compresses, what happens is it pushes the dart out of teh barrel as the spring accelerates, causing a relatively constant pressure. More air = more net pressure on the dart.
Pneumatic pressure at the start is far, far greater. The problem comes in with dead space. Air guns have a high nozzle pressure immediately but it drops as the dart moves. Dead space absorbs the pressure so with that arrangement at 3 pumps the pressure behind it is far far lower- useless, even.
Tilt the tank level with the NF barrel so the fill nozzle is in the back, mate the ball valve directly to the front of the tank, then you can attach a hopper, too. Problem solved.