Pumpers - Design/Mod Discussion Thread

[ten.ring]

  IT'S A GOOD THING I'M WORKING KNIGHTS. after reading this thread i would not be able to sleep.
in the back of my head i have had plans to build a .22  20fpe pumper with a second shot for 25 yrs. i started to look into it about two weeks ago. i have about 8 1/2 months before the contract i'm on ends. so i hoped that i could come up with a number of designs in that time to work on in my shop when i get back, to start the proptotype work. i figured on some test fixtures and some mock-ups.
i had NO IDEA that what i had planed on doing was of interest to anyone. i am so excited to see ALL that is going on. the number of my ideas that i was planing to do that have been done allready. i love to learn from others! it's a fast track to success. i'm relieved to see your calc's line up with mine. i was planing on going with a marauder for a foundation. a SIDE LEVER design. for my grand finally but will start out with a 13xx the learning curve will be cheeper.
  in the 80's i had a 13xx and it seemed to me it had a lot of unleashed possabilities. things like a metal breach in part so i could mount a scope and 2nd to float a 14" barrel, some valve work was obvious the cuped piston had to go, the trigger was junk.
what i have ordered online now puts me a year ahead on my project.
  1322
  shoulder stock
  metal breach 1steel 1aluminum
  flat-top and valve
  adj trigg
  14in barrel
  tko 5in break
  leapers 3-9 bugbuster
  weaver windage rings
some parts have come in already some on the way.
  i love to brag about my wife of 26yrs so here goes, she has never once even flinched at my projects in fact she is an enabler, not a obstacle. she encurages me every step of the way. WOW AM I BLESSED OR WHAT!
 

  mark   

[Bill G]

Bob are you thinking on the idea of single stage?  Is this going to be based off any certain platform or you thinking proto type ground up?

[rsterne]

I have two ideas in mind to try.... Both are based on a 392 linkage (one a billet from Mac1), and both have modded Disco valves.... One valve would be about 5cc with built in check in an extended front end.... It would have the option of adding a 16 gr. (20cc) CO2 cartridge in the stock (off the side of the gauge adapter) to increase the volume, and will likely use a 20" MRod barrel and shortened Disco tube.... The other idea is to use a full length Disco tube and a 24" barrel, and to mount the check valve about 4" ahead of the Disco valve, using that volume for retained air.... It will have a foster fitting to fill and the pump to refill.... Until I have a baseline and some experience using the 392 linkage I don't want to complicate things....

Bob

[spider1960]

I really like the UBER CARBINE. Fascinating thread.

Spider

[lloyd-ss]

................................. The other idea is to use a full length Disco tube and a 24" barrel, and to mount the check valve about 4" ahead of the Disco valve, using that volume for retained air.... It will have a foster fitting to fill and the pump to refill.... ...................

Bob

Bob,
So this pump would be within the pressurized tube, and would be fed by the diminishing air in the tube in front of the valve?  I think I like that.... a lot.
Lloyd-ss

[Bill G]

I like this idea also.  I had been imagining using a .25 Marauder and adapting the tube for a pumper.  Thinking that using the gauge port as a fill point from bottle but a gauge is a must, in this application, I would think .  Pump puts back what you just shot.  This type of project will have to be put on the back burner for a while due to limited financing.  I probably need to start building reg kits for the marauder for sale to finance such a project.  Need to finish the design to accommodate the gauge and give ample volume. 

[rsterne]

So this pump would be within the pressurized tube, and would be fed by the diminishing air in the tube in front of the valve?  I think I like that.... a lot.

Nope, hadn't considered doing that.... The plan was only to have the part of the tube behind the check valve pressurized (about 4" long?).... The forward section needs to have a slot for the linkage in about the front 8", and then the piston is about 7-8" long, all of that in front of the check valve.... The foster would be either in the part that holds the check valve, or more likely sticking out the side of the tube above the gauge, mounted into the forward extension of the valve....

However, I do understand what you are saying, to have the piston operating inside the pressurized section.... and basically moving air from the forward portion of that section to the rear portion.... I have no idea how to do that, at the moment though.... but it's worth some thought....

Bob

[ten.ring]

bob:
  have you seen the benjamin pump-assist 392, (pyramyd air report nov 5-07)(since i can't post extenal links you can do a search for your self for this)  ,  or the benjamin turbo air you can find the turbo air on crosmans blog under products. 
i used a similar thee bar linkage on a pallet loader back in the late 70's. this guy bob moss. says he has a patent on it. i would have to guess it's an application patent because it's only a common 5 bar linkage system not some new mechanism.   
this would do for you what your looking to get done. i can not think of any other posibilities. the sliding linkage  from the green forum would be very difficult to control.
i lean towards a side lever because there is more room for a longer pump arm. which could be extended to pump then pushed back when the pump arm is home. i have found that the simplest way that works is the best way to do it. with a side lever the pump arm could be close to 2x as long compared to an under lever.

[rsterne]

I've seen the Bob Moss linkage, and he is very specific about not using it past 8 pumps.... I assume that is a strength/stiffness issue with the linkage, much like the stock linkage on a 39X.... It is interesting to see in action, though.... Most of the more complex designs need a lot of attention paid to design details to make them strong/stiff enough....

Bob

[ten.ring]

 the device is not inherently week. i think bob is one of those indispensable phd's that made it posible to do my job but has limited mechanical understanding. he also is adamant about not pumping a stock 392 past 8.
  i'll bet  that "pakprotector" can come up with a program that will make the geometry easy, if the links are right there will be no binding. that is the biggest problem with multi link devices. i moved 600lb pallets SIDEWAYS on a roller conveyor. with one that fit in a 3in wide gap.
 
 my self i'm going with long, it's simple put there aint no room under a rifle for that.

mark

[JerryW]

Question for Bob - Have you ever measured how many pounds are needed to close the pump arm on your Millennium Pumper or your Disco Pumper at full pressure? Maybe if you closed the arm on a bathroom scale(crude, but close enough).

I'm in the thinking-it-through phase of designing a scratch built air conserving pumper and I can't decide if I want to use .745" i.d. or try .870" i.d., along with the 7.5" Benji stroke.

Thanks,
Jerry

P.S. - I hate to see this great thread fade away.

[Matt15]

P.S. - I hate to see this great thread fade away.

I agree so I will bring it back I want to get the max power out of my crosman 2100 pumper. What can I do to get it there. I am going to FT.

[rsterne]

This thread didn't die, it became a .25 cal Disco Pumper Carbine and then the Millenium Pumper....

http://www.gatewaytoairguns.org/GTA/index.php?topic=37401.0

http://www.gatewaytoairguns.org/GTA/index.php?topic=39328.0

Bob

[Matt15]

This thread didn't die, it became a .25 cal Disco Pumper Carbine and then the Millenium Pumper....

http://www.gatewaytoairguns.org/GTA/index.php?topic=37401.0

http://www.gatewaytoairguns.org/GTA/index.php?topic=39328.0

Bob

Very cool.