SpudFiles

assuming your's and my interpretation of deadspace are the same. what i'm calling deadspace is the volume of air that resides in the area between the bottom of the piston at it's lower most position and the top of the sealing face of the check valve when closed.
currently the piston in my pump sits above the bolt in the below wog check valve. actually 3/16"(.1875") above the sealing face. my piston diameter is .785". this gives me a whopping 0.091 cu. in minus the volume of the head of the bolt.
so comparatively you have more deadspace than my store bought valve.
while the pressure is only rated to 250 psi, it doesn't have to be assembled from various parts.

great job.. it looks so clean and....hmm.... portable 8)

by reducing the diameter of the piston by a factor 2 you can increase the pressure by the factor of 4 ? do I get it right ?

I didn't know you could even get an inline check like that. If I had known, I probably would have gone that route too. The only checks I have seen in the local stores were of the "swinging flap" variety.

Thanks for raising the issue, this will simplify construction for those who can get one. It's a good find.

Poland spud, thank you and yes, you get it right.

too funny, i've never actually seen the 'swinging flap' kind at any store or wholesaler, only in remodels that i've yanked them out of antiquated mechanical rooms.

@Gippeto: pretty sure he made it himself..

Spring loaded piston check valves can be found on mcmaster.

http://www.mcmaster.com/nav/enter.asp?pagenum=463

I cheated when I made my check valve for my pump. I used a comp fitting that went over the bottom of the pump shaft, I had a washer directly pushing the bottom of pipe. Just saves on a hell of alot of parts.

bluerussetboy wrote:too funny, i've never actually seen the 'swinging flap' kind at any store or wholesaler

Are you sure, you do occasionally get slutty looking girls behind the counter

jackssmirkingrevenge wrote:

bluerussetboy wrote:too funny, i've never actually seen the 'swinging flap' kind at any store or wholesaler

Are you sure, you do occasionally get slutty looking girls behind the counter

And how many of those have you "fixed up" JSR?

There's no fixing a swinging flap once it's inexorably lost the argument with Hooke's law

We're gonna need an AO section soon

Maybe we should have a 'spoiler' censor like the one on IMDB, hover your mouse over the censored bit and it shows the text.

I really don't see why people don't make more pumps. Surely if anyone has the gear and the know how to make a spud gun, surely they can apply that knowledge to making a 300psi+ pump that will just increase the sh!t out of any gun.

MrCrowley wrote:We're gonna need an AO section soon

Not being as subtle as I used to eh? I do, honestly, try and keep back, but some opportunities are just too good to miss

The tutorial is up now.

I'll find a higher range gage tomorrow and see what it'll make and hold pressure wise. I'll edit the tutorial to include this info.



Well, it's monday. I found a 600psi gage (borrowed) and installed it. I moved my pump handle up and used a feeler gage to measure the gap (~.036"). Measuring this gap after the test should give me some indication of how well my check valve is holding up.

As of now, the pump has been holding ~408 psi for 2 hours.

If the check valve does not bend (it should not, the copper is the weak link), I will be completely satisfied with the pump as is. To get much past this pressure, your going to need serious muscle to work the pump.

400psi....Geez mate.. Thats nuts. I've hit a wall with my pump. I can't find any right fitting o-rings .