SpudFiles

here's a pump I've just finished putting together, I wanted something with the speed of a track pump but the higher pressure capability of a shock pump, I've seen a few nice pumps on this site and some hints on how to take it a step further.
I didn't feel like going down the fridge pump route, it feels kind of like cheating not to mention reliance on the national grid, environmental terrorism, and just plain lazy (I can say that, I only have a small chamber to fill )
the pump:


It is a two stage design which I have taken up to 600psi so far without any difficulty, I'm sure it could go higher but I'm worried about deforming the copper, and don't have the right gauge, nor any reason to, yet.
the 1st stage is a length of 22mm OD copper, on the upstroke this is compressed into a smaller 15mm OD cylinder before being further compressed on the downstroke. The idea here is to combine the ease of pumping of the 15mm cylinder with the larger volume of the 22mm cylinder:


one piston is aluminium the other brass (just what i could find) both turned on my pillar drill. Both use floating o-rings which allow air flow in one direction, each in opposing directions:

(NOTE: the shaft on the 22mm piston is reversed in the pump, the piston on the right is for a separate project)

the piston shafts are M6 steel rod epoxy sleeved with 3/8 aluminium tube. The base fittings are solder fittings, the top fittings are push fit for servicability. The shaft seals are a collection of o-rings and spacer rings all crimped into sections of 22mm copper with the help of a 'pipe cutter':

The check valve was the only part of the build which gave me any hassle, I splashed out on a stainless steel 40bar check valve but it didn't seal properly so I replaced the plastic piston for a brass and rubber one which works ok.

(original piston on top, rebuilt piston below)
To reduce the dead space in front of the check valve there is a bolt projecting from the front of the 15mm piston which fills the fitting to the base of the elbow, I could have mounted the check valve directly to the cylinder but wanted to keep both cylinders the same length.

Questions welcome.

cool, very nice pump, I wish they sold those!

Nicely Done.... any frame of referance of # of strokes to fill x volume to pressure???


do you think making the first stage much larger would have made it nore difficult on the upstroke???

couldnt you try attaching the pistons at the bottom, I have a foot pump like that.

They do sell them. You can buy two or three stage pumps for PCP rifles and topping off HPA cylinders, but they are rather expensive.

Very good pump! I had a think after seeing this of making my pump out of a 3/4" aluminum pipe going to a 1/2" aluminum pipe (O.D's) but decided against it. I only need 300-400 psi..

Still, awesome and good way of making a 2 stage! Can actually be achieved by those without lathes.

that is so good
lovely look and good idea to get hpa with less time
15 mm you can get 75 bar for me its 85 moar wight

jeepkahn wrote:do you think making the first stage much larger would have made it nore difficult on the upstroke???

just like what he says

Cool. At first I thought it was a pump with two cylinders, but then I realized it was a two-stage. Good job.

Excellent work! :thumbright: :thumbright:

Elegantly simple two stage design.

Love it! You should sell them!

Nicely Done.... any frame of referance of # of strokes to fill x volume to pressure???

it takes 10 strokes to take the 1/4" fill hose and fittings upto 40bar

do you think making the first stage much larger would have made it nore difficult on the upstroke???

yes but its not too bad as it is, if I was malking it again I might try a slightly larger diameter for the first stage.

Very good pump! I had a think after seeing this of making my pump out of a 3/4" aluminum pipe going to a 1/2" aluminum pipe (O.D's) but decided against it. I only need 300-400 psi..

I would have liked to use ali, its readily available with a thicker wall for a bit more stiffness, but opted for copper so i could use solder fittings.

that is so good
lovely look and good idea to get hpa with less time
15 mm you can get 75 bar for me its 85 moar wight

thanks, dead space and the available compression ratio will always limit the pressure you can actually get to below what you might expect.

Cool. At first I thought it was a pump with two cylinders, but then I realized it was a two-stage. Good job.

Actually, I initially planned to make a simple two cylinder pump with a ball valve to switch out the larger cylinder at higher pressures, but then thought I would take it a stage further when I worked out how the shaft seals could be done.

Excellent work!

Elegantly simple two stage design.

Thanks, I think I got the idea for making it two stage from one of your pump threads

Love it! You should sell them!

haha, it took far too long for that, cutting and drilling the stainless steel base plate in particular was a real sod.

wow mate very nice! I assume a HP gun from you soon then?

Very impressive and well put together, both in terms of function and workmanship, kudos

I didn't feel like going down the fridge pump route, it feels kind of like cheating not to mention reliance on the national grid, environmental terrorism

I like the idea of a standalone unit that doesn't rely on external sources other than human power to achieve its effect.

Brilliant mate, absolutely brilliant. I really do take my hat off to you in this one.

Can't wait to see a nice sized bore using the sort of HP that thing will create.

very nice pump man.

would it work to attach the outlet of a 100psi compressor to the second stage inlet instead of having a first stage?

also i dont understand floating orings so if some one could help me with that it would be great!

The floating 0-rings on the shaft float because depending on their application, the seal has to be broken and re-seal. With the larger pump, it's to pump air into the smaller on the up stoke, and then the seal to break so it can re-fill on the downstroke.

Opposite with the smaller chamber. On the the upstroke the seal has to break to allow the chamber to fill, and then seal to further compress and push the air out the check valve.

(feels like a nerd)