.22 ACP Build-A Work in progress

[JuryRigger]

I have been working on several different configurations for this build for some time now; I think that I have settled on a final arrangement. I am trying to achieve 60-ish FPE from a self-contained platform; using as few additional purchased components as necessary. I still have much engineering work to do, I have only done some rough calculations on the tube's strength and believe it will suffice.
I am going to roughly mock an Airforce  Condor/Edge, in the overall drawing the main tube will serve as both the tank and the frame. I will be using 1" OD .120" wall 1020 DOM tubing that I already have; it will stay as one piece to form both the tank and the frame. I estimate that I will have an 85 CC reservoir, which will be run at approximately 3000 PSI. The tube has sufficient thickness for the forend/trigger block and top rails to screw on; the pump tube will be joined to the tank through a banjo-bolt type setup. I mocked up a breech/hammer design based off eye-ball "scaled" pics of components for Condors on the web; it was only for me to get an idea on overall size, if anyone has solid information on Airforce Condor/Talon valve/breech/hammer design , it would be helpful. I will post pics of the other configurations that I thought of, if they could be of help to anybody. It will be a while before parts actually begin to be made; I am staying at home due to COVID; and have no machine tools. As of the moment; I am currently building a small lathe, approx. 3" swing by 22" between centers.  It should be of sufficient size to perform all required turning for this build;  the other parts that would require milling will have to be able to be filed out.
I will post revised drawings/other design concepts as I get them drawn out.
Here goes:

[Rob M]

my only advice, MORE leverage.. but it makes peerfect sense ,. and this configuratioin might actually save you sopme fabrication.
So 1 " -.240 = a .760 piston. Past about 2200 psi that will be very hard to pump  with a standard single pivot linkage. turning the pump sideways and having a long sidelever would make it easy..

the force required for 3000 psi is 1360LBS on the piston face.So even at 20-1 mechanical advantage youre still pushing 68lbs on the final pumps.( dont get me wrong 40-1 or 60-1 are very possible,) . And that all sounds fine , but these numbers assume ideal efficiency , no friction, no losses and so on. food for thought.

[JuryRigger]

Good point Rob, I "modeled" the stroke at various points and I thought it would work, but having never owned/handled a pumper I have no way to "gage" ideas compared to a real-world experience... I have a compound linkage idea I'm playing with, it is a variant of an design posted here for an SSP a long time ago... I still have to draw it up, but might have it posted tonight.
Thanks for the feedback,
Jesse

[Rob M]

an easier way to get it all going would be to chop an existing pumper , lets say a 760 since its cheap etc//
solid flat top internals ,pinned valve , and use the existing valve as your check valve ( since it has one alrerady )  remove the stem and poppet , have it fill your 80cc section of tube which connects to the airforce valve .

[JuryRigger]

Rob, cannibalizing a 760 or other pumper would be a good idea; but as of now I am currently trying to keep costs at an absolute dead minimum. I already have a gage, silicone grease/oil, a stick of 3/8" PEEK, and enough random steel/stainless/brass and bronze stock for all mechanical components. I will only have to purchase the seals, the barrel, and valve pinning/other hardware (plus a hammer spring). I even have a scope. 
This is the SSP linkage that I based my design upon:



I am truly sorry, but I cannot remember who to credit with this design;  IIRC it was developed by a member here in an attempt at a 12-20 FPE SSP to produce for sale.
The intriguing part of this linkage (to me) is the ability to use almost the whole pump tube length as swept volume; in my case clearance becomes an issue as well as stability of the long thin pump rod. In my drawing, I have shrunk the pump to .75" OD .62" ID tubing; with a stroke of 2.87" so displacing .86 cubic inch. I may enlarge the pump tube to gain more swept volume; but as-is the reservoir/plenum should be big enough to give 2-3+ solid shots; enough for hunting so I am not overly concerned with rapid recharge-ability. As can be seen, the leverage ratio increases as the lever is brought home; at .090 headspace or approx. 462 PSI, there is still 4" of lever travel to go. That gives a minimum leverage ratio from that point forward of 44.4 to 1, the handle force at 3KSI will then be .62" dia=905 lbs thrust /44.4= 20 pounds. That would seem a reasonable effort; if I up the tube volume to .76" ID it would be about 1.5x that or 30 pounds; then giving a swept volume of 1.3 cubic inches a stroke.
Jesse

[Rob M]

i beleive the 2 arm wine bottle opener design was patented by crosman for the turbo air pump they never released.. and agreed , its maximizing the use of the tube length.There was also an ssp builder using the same linkage  on youtube. The reason i mention the cannabalized parts, is that fabbing a pumper linkage , piston , and so on is very time consuming.

[JuryRigger]

Very true, it would save time... I shall think about it, as it will be awhile before I can start making chips anyhow.
Jesse

[sb327]

I will definitely be following along. I think you have an interesting concept there. I really don’t have anything to add except encouragement.

I really like scratch builds!

Dave

[JuryRigger]

Thanks, glad you'll enjoy it . After seeing your Airforce-type build, I got to thinking on this arrangement and liked it. Hope you have plenty of popcorn, this may take some time LOL.
Jesse

[sb327]

I’m a patient person.

It sounds as though you have three projects going on here. A lathe, a rifle and a pump. So undoubtedly, it will take some time.

What caliber?

Dave

[JuryRigger]

Don't have any progress to add on the gun, but am getting there on the lathe:

[Rob M]

nice ,are you handscraping the entire bed and ways ?

[JuryRigger]

That's just a preliminary "practice" scrape on the bed, I still have to grind a center relief to get the plug welds out of the way... I will be scraping in all the sliding surfaces, the dovetails are just filed out at the moment and my filing skills leave a less-than-flat surface. I haven't scraped in anything start to finish yet, was something that I always intended to learn (bought the blueing, a small surface plate, made a HSS bladed scraper etc.) but never had the time to actually learn the art...
Jesse

[Blutroop]

I’d put a foster fitting in it so you could use it like a pcp when you have access to a tank or compressor but still be a acp

[JuryRigger]

Update:
Sb327, it's a .22. Want to keep standardized ammo around as my 350 Mag is .22 also.
Blutroop, I will do that. Mainly wanted an on-board pump for independence in the field; I may get a normal PCP handpump for regular shooting.

Have reverted to a standard pump linkage; the design I started looking into in previous sketches looked nice on paper; but I'll be danged if I can figure out a good way to build it....  Will just have to settle for a smaller pump bore and a standard linkage; think I can get away with a .62" ID tube. with a 3.25" stroke.
Have a unique thought on valve pinning, using shoulder bolts. 5/32 diameter high-precision shoulder bolts from McMaster are rated at 84 KSI shear, crunch the numbers and you get 1610 lbs single shear. 2 bolts in double shear gives a break strength of 6442 lbs, safety factor with 3000 psi in the tube is a 4.73:1 safety margin. I think I can get away with dual-purposing the bolts to hold a top scope rail/mount and the trigger group bar at the same time. The tube wall looks like it will yield (just barely) before the bolts snap; I will clarify this will only be used for pinning the valve.
Any thoughts?

[Rob M]

ive done that pinning before , even with a single dowel ( .25 ) going through both sides of the tube.. Yes the math generally says the tube will deform before the pin breaks.. 2 smaller ones does the same trick.. I prefer to do 1 , less work involved.( the one pin is more centered on the tube with the bleed hole offset

[JuryRigger]

I actually thought of the idea from seeing your post on another thread; then got to thinking of dual purposing the bolts to hold the other parts on, too.
Jesse

[Rob M]

idea.. 2 760 pump assemblies side by side .. then , using the factory front valve check valves , it would be easy to thread those to a manifold .. that manifold joins to the plenum.. Youd have double the swept volume , easy plumbing like connections ( the valve fronts are 1/2-20 males) .. super simple .. Pumping will get hard , but thats a good thing.. Link the 2 forearms with one master forearm ( a 2 by 4 with a smiley face )
this could be done with a hacksaw , some home depot fittings, a block of aluminum , a drill press and a few taps.

[JuryRigger]

Now you have me interested in 760 pump bodies, did not know the valves were threaded 1/2-20. I have taps and dies covering 4-40 thru 1/2-20 UNC/UNF so fabbing the connector would be easy. Do you know the outer diameter of a 760 tube offhand?
Jesse
You also roughly approximated my tool list.. Have a full 0-6 Starrett micrometer set, 0-12 depth mic, calipers, gauge blocks, test/dial indicators, 9x12 surface plate, lots more.... Just no "machine" tools past a beat-up drill press. Hacksaw, dremel, files, and a couple cold chisels. Ugh. Nice to be able to measure 100x more accurately than you can produce........

[Rob M]

the tubes are .750 o.d .620 id.

yea, it would be simple.. Even before i had any lathe or mill , I made a contraption similar to this idea with just a drill press and some taps ..

to be clear , i bleieve the 760 threads are an npt thread that 1/2-20 happens to fit perfectly ( 1/4-18NPT or something )

Lets assume all this stuff is figured out , what needs to be built on the front side of the gun?