Author Topic: Building a Modern Pneumatic Airgun  (Read 113253 times)

Offline Stot

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Building a Modern Pneumatic Airgun
« on: November 03, 2010, 08:28:15 AM »
Take 2....

Welllll....  Ive made lots since last time I posted, mostly gun stuff for my Air Rifles, but my current project is worthy of a project log.

I bought a book by H.M. Buckley called The Modern Pneumatic Airgun.   Its a well written explanation on the theories behind operation, some nice machining tricks and full plans to design and build a PCP Air Rifle.  You can get the book by emailing Howard directly.   He also does a follow up book that concentrates on making an air rifle with the air tube in the stock rather than under the barrel, like a Gunpower rifle.

I'm at the stage where I have accumulates most of the materials to make the rifles and spent maybe 60 to get enough material for 2 full rifles + some spare parts.  The most expensive part is the barrel as this cant really be made at home.  Its not impossible, but impractical.  Luckilly I managed to pick up a 24" .22 barrel for just 20.



Ill keep a log of what Im doing here..  Hopefully. :poke:
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Offline Stot

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Re: Building a Modern Pneumatic Airgun
« Reply #1 on: November 03, 2010, 08:38:46 AM »
Ok part 2...

First thing to do was prepare the air tubes.   You can make these any length you want within reason, but the longer they are, the more air stored, the more shots you get.   With the UK limit of 12ft.lbf for an unlicenced airgun, these air tubes at 450mm long should get 70 shots or so in .22.  

I used aluminium for the air tube hence the thick wall.  These will be holding 3000psi+

So basically the pics below show that I.
  • chucked up the tube
  • faced off the end
  • Measured the bore with some telescoping guages and a micrometer
  • bored out the tube slightly to the minor size for the thread I was cutting
  • cut the thread.









I use an old 2 flute milling bit as a boring tool.  They work really well for this.





Repeat 3 more times and give a cursory polish.  :thumbup:



Cheers
Stot
« Last Edit: November 03, 2010, 08:43:14 AM by Stot »
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Offline Brass_Machine

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Re: Building a Modern Pneumatic Airgun
« Reply #2 on: November 03, 2010, 10:42:13 AM »
Thanks Stot for reposting. Got a lot of guys interested in this one :)

Eric
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Offline j45on

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Re: Building a Modern Pneumatic Airgun
« Reply #3 on: November 03, 2010, 02:33:56 PM »
Interesting stuff  :thumbup: keep it coming

Edit : will you be making a pump as well or do you decant from another bottle ?
And how much is the book ?
« Last Edit: November 03, 2010, 04:47:06 PM by j45on »
Jason

Offline Stot

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Re: Building a Modern Pneumatic Airgun
« Reply #4 on: November 03, 2010, 04:59:30 PM »
Hi Jason,

I have an FX pump that will pump up to 250bar.   I don't have a bottle, I'm too lazy to keep getting them filled.  :coffee:

The book was 30 + post,   13 air mail or 8 surface mail USA / rest of the world; 6.50 Europe and 4.50 UK.  Its a big old book.

Cheers
Stot
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Offline Stot

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Update 2 - Inlet Valve Housing
« Reply #5 on: November 04, 2010, 06:27:40 PM »
Ok 1/2 way though the air inlet valve.

The ends of the air tube are brass valves.  One end allows air in only at the muzzle end, the other end is a poppet hammer valve that will momentarily open to allow air to escape.

As far as machining goes the brass valve housings are 80% the same, so ill cover it once here, and then just show what Is different on the poppet valve when I do that.

The Inlet end calls for a standard 1/8 BSF high pressure air thread for filling.  This is where I am making my first change to the design.  I wont be using the standard fitting to fill, instead I will use a BSA style quick fill probe.  This works by just slipping an o-ringed probe into a filler port and starting to fill. ( more on that when i do the other end )

So,  Starting with a piece of solid brass I...

  • Faced off the bar and drilled and bored a series of 3 stepped holes.  These will house a sprung valve pin that acts as a 1 way valve.  The pin and spring is held in by a plug screw and the largest hole will be threaded later.
  • Turned the outside to be the major diameter of the thread to match the air tube.
  • Turned a step in the end of the valve housing to allow an o-ring to be positioned inside the unthreaded section of the airtube.
  • Threaded the valve housing to match the air tube.
  • Threaded the inside of the valve housing to take the plug screw.



























Thats as far as I got tonight.  Still, making good progress so far. :D

Cheers
Stot
« Last Edit: November 28, 2010, 09:50:10 AM by Stot »
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Offline Brass_Machine

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Re: Building a Modern Pneumatic Airgun
« Reply #6 on: November 04, 2010, 07:45:50 PM »
-- fixed your image tags. Fro some reason the pictures weren't showing up.

Very nice work. Threading looks great!

Eric
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Offline Stot

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Re: Building a Modern Pneumatic Airgun
« Reply #7 on: November 05, 2010, 03:26:51 AM »
-- fixed your image tags. Fro some reason the pictures weren't showing up.

Very nice work. Threading looks great!

Eric

Cheers Eric,  I must have left the ?attredirects=0 bit on the images.  :doh:

I put the good threads down to having a nice big sturdy machine.  :thumbup:

Cheers
Stot
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Offline geroli

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Re: Building a Modern Pneumatic Airgun
« Reply #8 on: November 05, 2010, 05:15:40 AM »
Nice job Stot

Keep it coming - hungry for more.

Gerhard
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Offline Brass_Machine

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Re: Building a Modern Pneumatic Airgun
« Reply #9 on: November 05, 2010, 10:38:12 AM »
Cheers Eric,  I must have left the ?attredirects=0 bit on the images.  :doh:

I put the good threads down to having a nice big sturdy machine.  :thumbup:

Cheers
Stot

Yup. No big deal. :)

Eric
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Offline Stot

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Update 3 - Inlet Valve Housing
« Reply #10 on: November 06, 2010, 10:26:34 AM »
Found a few hours this morning to finish the other end of my inlet valve, and make the other one too.  :clap:

The fill end of the valve would normally be just a threaded nub to connect to an air hose, kinda like a tyre valve.   I decided to go with a quick fill valve instead.   With the quick fill valve you have a probe on your air line with a hole coing through it crossways instead of out the end and 2 o-rings either side of the probes outlet.

You push the probe into a hole cross drilled into the end of the valve and as you pump the pressure seals the probe in by pushing in opposite directions against the two o-rings.  When you're done filling you relieve the pressure and just pull out the probe.  You can see the probe in the last couple of pics.

So, this part I...
  • Used the air tube as a mandrel for the valve.  This made it easier to hold and not damage the threads.
  • Turned down the end to have 3 steps, and faced it off down to dimension/
  • I files the burs off the edges and that was the turning done.
  • Mounted the valve in my 4 jaw chuck so that I could cross drill it.
  • I used an end mill smaller than the hole I wanted to make just to make sure I had the valve centered.  Its easy to see if a cylinder is centered by the mark an end mill makes.
  • Center drilled and then drilled a small hole all the way through the valve.
  • Drilled a hole the size of the fill probe to a preset depth.  I put an o-ring on the drill bit to let me know how far to drill.  This hole doesnt go all the way through but stops a couple of mm in from the other side.
  • Used a center drill to chamfer the edges so it doesn't damage the o-rings on the probe.































Thats the inlet valve housings done for both rifles.  The valve internals ill do in the week.

Cheers
Stot
« Last Edit: November 28, 2010, 09:49:24 AM by Stot »
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Offline Powder Keg

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Re: Building a Modern Pneumatic Airgun
« Reply #11 on: November 06, 2010, 11:22:12 AM »
Looking great so far!! I am interested in Air guns. But have never had the time to build one or even mod the ones that I own. I have the plans for 2 or three including one that looks like a cane. I would like to build that one one day:o)

Keep up the good work!!!
Wesley P
A Gismo ??? If it has a flywheel or spins and is made with small parts. I'll take one! If it makes noise, moves, or requires frequent oiling and dusting it's a better deal yet. It's especially right if its shiny and bright; but if it's dirty and dull it wont mater at all...

Offline johnbaz

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Re: Building a Modern Pneumatic Airgun
« Reply #12 on: November 06, 2010, 11:45:14 AM »
COR!! - This is sooo intersting!!, i love airguns and can't wait for the next update :clap:

My precharged rifles, the career has given me a hell of a lot of trouble but i have it shooting smoothly now, also the Huntsman sporter developed a leak, i had to strip it and re-face the valve as it had a nick in the face...



Good luck with the build :thumbup:


John :dremel:

Offline Stot

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Re: Building a Modern Pneumatic Airgun
« Reply #13 on: November 06, 2010, 12:10:11 PM »
Nice collection.  I have a 2 PCPs, a Parker Hale Phoenix and a BSA Ultra Multishot.  I also Have a Theoben SLR98, BSA Meteor, ASI Paratrooper, HW45 Pistol, Gamo P800 Pistol and a S&W 686 Pistol.

I did have an Alros Trailsman too and its a real simple take down PCP rifle.  Really easy to make so I think ill make my own version of that some day too.

I'd like to see that cane gun too.  Youre not allowed them here in the UK I believe Its classed as a concealed weapon.  ::)

I have other plans I bough for a multi stroke pneumatic rifle that look good too.

Cheers
Stot
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Offline johnbaz

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Re: Building a Modern Pneumatic Airgun
« Reply #14 on: November 06, 2010, 12:47:27 PM »
Hi Stot

I thought you were allowed to have the walking stick (air)guns as long as you didn't have any rounds for them, i think they all use obsolete calibres  ::)

I turned one down about fifteen years ago, it needed repairs but was only 30 :(

Here's the rest of my collection..


I also have a pistol collection, Webley's and BSA 240's



John :beer:

Offline Stot

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Update 4 - Poppet Valve Housing
« Reply #15 on: November 07, 2010, 09:31:40 AM »
Did the outlet valve housings today.

The outlet valves are poppet valves.  A sprung hammer strikes them to open the valve and let some air out, simple stuff really.

They are pretty much the same as the inlet valves other than the hole goes straight through which will hold the valve pin of the poppet valve, and the end is threaded to go into the hammer housing that will be made later.  There are still holes to be cross drilled on these but their position is dependant on the breech and trigger blocks so ill drill them when those parts are done.

As this is the pretty much the same operations as Ive already done,  Just some finished item shots. ;)











Cheers
Stot
« Last Edit: November 28, 2010, 09:48:40 AM by Stot »
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Offline Powder Keg

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Re: Building a Modern Pneumatic Airgun
« Reply #16 on: November 07, 2010, 10:36:28 AM »
Very professional looking parts there. I'm watching this one closely(o:
Wesley P
A Gismo ??? If it has a flywheel or spins and is made with small parts. I'll take one! If it makes noise, moves, or requires frequent oiling and dusting it's a better deal yet. It's especially right if its shiny and bright; but if it's dirty and dull it wont mater at all...

Offline j45on

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Re: Building a Modern Pneumatic Airgun
« Reply #17 on: November 07, 2010, 10:44:59 AM »
Me to  :bow:
I was not aware you could build your own air gun until I saw this thread
as I said before interesting stuff
Jason

Offline Stot

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Re: Building a Modern Pneumatic Airgun
« Reply #18 on: November 07, 2010, 11:06:23 AM »
Its bloody adictive too!   Im having to limit myself to 2-3 hours a day.  I've got about 10 hours in it so far and its mostly been by the book.

Ill do the valve internals tomorrow but I have to take a look at the hammer tube and bolt arangement now because I'm not overly keen on having a seperate bolt and hammer handles.

Cheers
Stot
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Offline johnbaz

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Re: Building a Modern Pneumatic Airgun
« Reply #19 on: November 07, 2010, 03:53:51 PM »
Fantastic work Stot- those threads are just soooooo smooooth :clap:

It's addictive reading too!!! :thumbup:


Cheers, John :beer:

Offline Brass_Machine

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Re: Building a Modern Pneumatic Airgun
« Reply #20 on: November 07, 2010, 04:23:02 PM »
OK, so I have to get that book so I can follow along with what you are doing.

I see another hobby on my horizon.

Eric
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Offline Stot

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Re: Building a Modern Pneumatic Airgun
« Reply #21 on: November 07, 2010, 04:49:52 PM »
OK, so I have to get that book so I can follow along with what you are doing.

I see another hobby on my horizon.

Eric

Ill be finished the gun by the time you get the book.  :lol:

If you do want it email Howard but hes old school so you wont get a reply for a while, But you will get a reply none the less.  :thumbup:

Cheers
Stot
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Offline Blade

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Re: Building a Modern Pneumatic Airgun
« Reply #22 on: November 07, 2010, 11:01:52 PM »
Great work! Can't wait to see how these finish out.

Offline Fred Bloggs

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Re: Building a Modern Pneumatic Airgun
« Reply #23 on: November 08, 2010, 11:14:01 AM »
Hi everyone

Saw the thread  :jaw:, thought great got to get me the book, so emailed Howard and he replied the same day, I think he's going to have quite alot of business in the next few weeks.

great work Stot

Fred

Offline Stot

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Re: Building a Modern Pneumatic Airgun
« Reply #24 on: November 08, 2010, 05:24:42 PM »
Great stuff.  Hope he does sell a few its a great book and a bargain for the info contained.

What I will say is make sure you know the law regarding air rifles before you start.  Its easy to fall outside of the law without knowing it and you could get in real trouble.

Cheers
Stot
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