Another way to get 400 psi

[BoyntonStu]

Another way to get 400 psi

Almost any 12 V 200 psi tire inflator can be purchased for under $20.

Some can do 250 an a few claim 300.

O.K.  We have 200 psi and we need to double it.

Let’s say that our chamber has a 4 cu in volume.

We have to compress 8 cu in into 4 cu inches to get 400 psi.

We need a piston whose face area is .5 sq inches.

A 0.8” diameter is almost .5 sq in.

If we apply 200 psi against a 0.5 sq in surface, we double the pressure to 400 psi.

All we need is a 4 cu in cylinder whose ID is 0.8”.

We apply the 200 psi from the pump against a free floating piston and push it to the bottom and out to the chamber.

Presto! 400 psi.  Inexpensive, compact, light, portable and pretty fast!

BoyntonStu

[Pellethuntr]

Hummm sounds complicated... I'm not making fun of you're idea but it's a little bit to complex for what u get out of it...Just use co2 it will save u some trouble.

[theairgunman]

Sounds kinda like those booster pump setups used to top off a scuba tank or HPA bottle with a standard air compressor. The only thing is those portable compressors arent nearly as good as they used to be. I had one that would take airguns up to 300 psi and worked great for 3 years before it died. Now most of them labor to get to 200 and if you do it often, they croak. If we could find a practical way to make a 2 stage hand pump with commonly available parts and no machining required, that would be awesome! I think I'm just going to have to settle with 2 small hand pumps for now. One will be made from 3/4" type L and the other will be 1/2" type L. Between the two, I should be able to get to 400 psi in under 75 strokes (that still isnt very good, but better than what my shock pump does!)

[boar]

I think you could probbably get away with just the 3/4 bore pump for 400 psi if your pretty good size guy and if you build the pump of a size and configuration where you could get into a good pumping position for that matter you could probably get away with just a 1/2 pump built a little taller than a bike pump youl be picking up alot more volume than u get with your shock pump

Boar

[theairgunman]

I'm lucky to weigh in at 150, and I'm a bit over 6 ft. tall.  lol I eat like crazy, but my job keeps me moving nonstop so I really cant gain any weight. Actually, I think I can get by with a 3/4" pump by "pegging" it as was done in times past with airguns. I'm going to build it first and see if I really need a smaller one. It needs to be small enough to be practical to take out in the woods with me, that's why I'm guessing I'll need a smaller one too...