SpudFiles

Gippeto wrote:
That 22kg with a 4:1 lever would only be a little over 5kg.

Have the P17 back together and will bring it in to test on the scale.

I realised that my earlier calculation is wrong, 1" bore makes 0.785in2 bore area and to get 150 psi it needs 117.75lb which makes 53kg.. That would need 10:1 lever to pump.

Took 25 lbs of force to close the lever measuring with the bathroom scale. This works out to ~132psi (910kpa)....much lower than I thought it would be. Will run it over the chrony to check velocity.

On the face of things, seems 130ish psi might be enough to be viable....

btw i checked again the calculation for a 3/4" bore diameter and 130psi pressure it needs 57lbs
and 3:1 lever would be fairly easy to cock the system.

Theres one more thing here, to achieve a 130psi compressed air with 3/4" bore and 4" stroke length a 8,96552 mechanical compression ratio is required and it will need 0,197in3 head space in chamber.

From what i understand there will be 0,197in3 of compressed air and this needs to be at least 2 - 2,5 times the barrel volume to launch something from it doesn't it..?

Are you planning on 1 pump to build the pressure or multiple pumps ?

I'm actually getting interested in this now, if I didn't already have 4 diiferent guns on the drawing board already this could be No. 5

This may help, I like the way the pump linkage changes as the piston reaches it's end of stroke.

Thanks for your interest, hope I can get this project to an end, the idea was simply a pellet or bb gun like pcp but without the "pre" charged side. So it needs a pump within. Like the one you posted, the 1377 or p17 or the one with Zoraki hp01. (BTW I really like the design and working principle of crosman 1377 i think it's simple and brilliant.)

Here the multipump action seems a bit hard to replicate because of the air compression chamber with 2 valves on 2 ends. (The orange part above the trigger on your posts image) The one in p17, which I'll try to replicate, may work with a simple extra space in the pump as a compression chamber. (Will be way easier I guess)

Another great fantasy about this project is multipumping the air to another chamber and using the compressed air for a minimum of 5-6 shots. Like I said earlier I am new to pneumatics so guess I first have to start with easy things.

(Ordered some steel pipes, fittings, valves and a qev already)

Rather than an air cylinder have you considered using an inexpensive pump? That will have a handle and check valve in it. You might still want a linkage for leverage.

Hello there, after Gippeto's opinion i am thinking of making the pump myself
Guess it'll be the first finished part.

I tried a small cylinder as a pump, I think it was 1" bore, 2" stroke, managed to get 130psi on the full bore side, so now I am wondering if this would work, the reduced bore rod side would act as a precharge pump

my idea is a little bit different do you have a software to draw these or are you drawing in paint..?
btw sorry but i have to ask, do you have any equipment to try this..?, i need someone to tell it works..

I like to use MS Visio for the basic line drawings, all the parts are already loaded, you just drag and drop then connect them.



I do dabble with Solid Works sometimes



There is simulator software as well if you want to try pneumatic layouts

thats nice thanks for the info, btw the more i looked at your design the more i liked it.
Do you think a cylinder can fill a 100-150cc air chamber to 130psi by pumping..?
İ don't know how to do it but this may lead to a semi auto.

farcticox1 wrote:now I am wondering if this would work, the reduced bore rod side would act as a precharge pump

It won't. In a double-acting configuration like this, the first stage would need to have a higher volume than the second, else you're not increasing the pre-charge pressure in the second stage.

Here, the first stage actually has a *lower* volume, so it's doing nothing useful. It just means the pump is drawing in most* of its air on the compression stroke rather than the return stroke, but I don't see any benefit to doing so.

*As the internal volume of the cylinder actually increases as the rod slides out, it would actually still need to draw in some air on the return stroke.

Mates i was searching for homemaid airguns on youtube and ound something interesting here;

but couldnt understand where this one stores the compressed air, does it store it in the hose..? is it even safe..?

btw if anyone can understand how it works can you please explain it please..?

I'm not entirely sure. It's possible it's a coaxial configuration.