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Air Gun Home Forum Index » Airgun Smithing » New Old Project - Hayabusa PCP - Mark III Version Goto page 1, 2, 3, 4, 5, 6, 7, 8, 9, 10  Next
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New Old Project - Hayabusa PCP - Mark III Version 
PostPosted: Thu Jan 27, 2011 5:49 pm Reply with quote
rsterne
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I decided last summer that my winter project this year would be a "Scratch Built" PCP rifle.... Perhaps I should call it a "Custom" since I will be buying some of the parts, such as the barrel, trigger group, tank, and stock.... Regardless of the semantics, this project is a step up from purchasing parts (with a few bits I made thrown in) and assembling them.... Where possible, given my limited skills and machine tools, I will be making most of the metal parts from billet.... I have christened the gun the "Hayabusa" which is the Japanese name for the Peregrine Falcon, the fastest animal on earth....

I plan on building two guns, one this winter and the other next (assuming the first one works).... This year's gun will be interchangeable .22 and .25 cal using 0.630"D x 23.8" long choked Lothar Walther barrels.... and I hope to test a polygonal barrel in .25 cal as well.... The follow-up, next winter, will be interchangeable .30 cal and 9mm, using 28" LW barrels.... The main tube is 1" OD x 0.065" wall 4130 tubing.... It will be fed by a 22ci. 3000 psi tank and Ninja regulator set (initially) for 2000 psi.... The entire main tube is downstream of the regulator, and the plenum volume (ie between the regulator and valve) will be about 7 ci (115 cc).... nearly the size of the entire air reservoir in a Disco.... The valve is larger than a Disco valve at 0.87" OD which allows larger porting, although the poppet is from a Disco.... I really like their over-molded design and it's plenty big enough to allow a 5/16" throat.... although this gun uses 1/4" ID at the valve seat and 3/16" through ports.... plenty big enough for a .25 cal....



The valve is only the back end (I believe it's called a spool valve?), with the poppet, ports, O-ring and mounting screws.... There will be a spring to hold the poppet closed when the reservoir is empty.... however, there will be basically no restriction between the plenum and the valve.... making the valve volume virtually 115cc.... Even with an air-gulping 9mm I expect the plenum (and therefore valve) internal pressure to stay above 1600 psi (ie average ~1800).... and in the .25 cal the pressure should average around 1950 psi during the shot cycle.... It is this high AVERAGE pressure that I hope will produce some very satisfactory results.... Mr. Green

I designed and built the "reversed" tank block so that the tank is turned around, with the regulator at the front and the tank itself becomes the fore-stock.... The tank block (and the valve) will be mounted with three 10-32 (high tensile) low profile SHCSs with the head spreading the bearing load out into the tube.... The calculated safety margins for the various parts under load (at 2000 psi) are as follows: Tube: 4.7:1.... Screw Shear Strength: 3.9:1.... Tube Bearing Area: 3.2:1.... Tear Out: 6.6:1.... In the event of a regulator failure, the lowest common denominator (the tube yielding around the screw heads) will still have a safety margin of over 2:1 at 3000 psi.... The tank block is threaded for the output of the regulator and acts as the front tank mount.... It contains a gauge for the low pressure side so that I know what the pressure is in the plenum.... On the top is a machined shoulder with two tapped holes to mount a barrel band.... on the bottom is a 3-slot Picatinny Rail for mounting a Bi-Pod....

I hate the way Crosman mount their breech with a tiny screw under the bolt.... and I also wanted to eliminate any hole in the tube for the front trigger mount.... I therefore came up with a rather novel assembly which will mount the back of the tank, the front of the trigger, and wrap around the main tube... It will be pulled upwards with two 6-32 SHCSs coming down through he breech either side of the barrel.... There will be a notch in the bottom of the breech (below the barrel) to clear (and locate) the top of this tank band/trigger mount assembly.... Once the bolts are tightened, the entire assembly will become rigid....



There is still a lot to do.... I have to make a breech, bolt(s), hammer(s), RVA, and do all the machining on the tube.... plus the necessary machining on the barrels when they arrive.... I'm going to try and make an adjustable transfer port as well.... and I may also experiment with an adjustable hammer fall, similar to the one in a Marauder, which adjusts the length of the front striker on the hammer.... I have a Marauder stock coming which will be cut off just in front of the trigger to fit up against the back of the tank.... and then I have to figure out how to mount the back of the receiver to the stock as well.... However, I thought I would give everyone a "sneak peak" at the progress on my latest project.... Mr. Green

Bob

PS: When I was trying to come up with a name for the gun.... my wife suggested "the Widowmaker".... because she has hardly seen me over the last couple of weeks.... Embarassed

RBS


Last edited by rsterne on Sat Feb 08, 2014 3:06 pm; edited 2 times in total

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PostPosted: Thu Jan 27, 2011 5:56 pm Reply with quote
69Hotrod69
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Looks like a great start Bob!

I like the idea of the valve being fully open to the reservoir.

let me know if you ever want some CAD-CAM Drawings or Programing. I'm a little rusty but still have my software and would enjoy helping out.

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PostPosted: Thu Jan 27, 2011 6:02 pm Reply with quote
69Hotrod69
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Bob forgot to tell you Jay has his breech's for the 22XX using Marauder clip looks good and it comes with a clamp to mount breech to the tube no dinky screw. Might save you some time? although it seems your goal is to make a one off.
Just wanted to mention it.

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PostPosted: Thu Jan 27, 2011 6:15 pm Reply with quote
rsterne
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I've seen it.... it's designed for a 22XX tube which is smaller than mine.... and for a 7/16" barrel whereas mine is ~5/8".... My first version will likely have a single shot breech.... but I do have some .25 cal MRod magazines coming and may use those in the future....

I've tried doing some CAD stuff and the programs just have too big a learning curve.... All my machines are manual.... actually, everything was built on a 12x36 Atlas lathe with a milling attachment.... Mr. Green

Bob

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PostPosted: Thu Jan 27, 2011 6:32 pm Reply with quote
69Hotrod69
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I was thinking if you wanted to make multiples after your prototype is finished. Very Happy

Yea I guess it would be a little steep to buy one and have to modify it. Shocked

I have no real machines right now I did everything on my Marauder and my R3 2260 Carbine on a cheap Jet Drill press. Very frustrating for a Master Machanist to be reduced to hacking with little more than hand tools. I keep telling my wife I need to go back to work so I can do side jobs after hours. She says not until the baby is 2. Rolling Eyes She was born in Sep. I got a long wait. Laughing

You right about the learning curves, they take a long time to master then they come out with an update Evil or Very Mad

I drew my whole house in 3D on Master Cam because it was taking me to long to learn Autocad 2006. Which by the way is suited for architecture unlike Master-Cam Laughing ohh well you do the best with what ya got! At least I know how to program deburring cycles unlike Crosman products Laughing

What kind of barrel are you going to use?

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PostPosted: Thu Jan 27, 2011 6:40 pm Reply with quote
rsterne
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I'm going to be using Lothar Walther barrels in every caliber.... I have no plans to make any beyond the two....

Bob

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PostPosted: Thu Jan 27, 2011 6:43 pm Reply with quote
kanyon
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WOW..
That looks great....
can't wait to see how it shoots..

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PostPosted: Thu Jan 27, 2011 7:24 pm Reply with quote
69Hotrod69
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I've never owned a LW barrel but am thinking of ordering one soon.

Was just seeing if I could help you out in any way, because your posts
have been so valuable to me.

Rod

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PostPosted: Fri Jan 28, 2011 5:00 am Reply with quote
broommaster2000
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You got ME interested. Shocked

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PostPosted: Fri Jan 28, 2011 6:20 pm Reply with quote
yourdaddyjoe
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Looking awesome as usual there Bob!

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PostPosted: Wed Feb 02, 2011 7:58 pm Reply with quote
rsterne
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Had a chance to do a bit more machining today.... I made a couple of RVAs and a hammer.... The hammer is machined from 1045 steel which can be hardened once finished.... It weighs nearly 50% more than the hammer in a 22XX.... nearly 90 grams....



The hammer has an adjustment for the fall distance.... The 1/4"-28 NF set screw in the front as yet to be machined flat and hardened.... It is located by an 8-32 SHSS in the side with a small piece of plastic under it to act as a brake.... The hammer and the RVA screw are drilled through to allow adjustment of the hammer length without disassembly.... This arrangement is similar to that used in the Marauder.... As you lengthen the screw (by screwing it in clockwise) the hammer hits the valve stem sooner.... This gives the hammer less distance to accelerate and limits the valve opening.... As you back the screw out, the hammer accelerates more and has more momentum when it hits the valve.... opening it faster/further.... The hammer is also slightly overlength at the present time.... Once the parts are fitted into the tube I will machine it to length so that it just cocks reliably before hitting the front of the RVA.... The RVA works by adjusting the preload on the hammer spring, of course.... With two variables, there are lots of possibilities to adjust the hammer strike.... They interact, of course.... but it will be interesting to find out how each adjustment affects the performance and the shot to shot consistency....

Bob

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PostPosted: Wed Feb 02, 2011 8:34 pm Reply with quote
kanyon
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rsterne wrote:
Had a chance to do a bit more machining today.... I made a couple of RVAs and a hammer.... The hammer is machined from 1045 steel which can be hardened once finished.... It weighs nearly 50% more than the hammer in a 22XX.... nearly 90 grams....



The hammer has an adjustment for the fall distance.... The 1/4"-28 NF set screw in the front as yet to be machined flat and hardened.... It is located by an 8-32 SHSS in the side with a small piece of plastic under it to act as a brake.... The hammer and the RVA screw are drilled through to allow adjustment of the hammer length without disassembly.... This arrangement is similar to that used in the Marauder.... As you lengthen the screw (by screwing it in clockwise) the hammer hits the valve stem sooner.... This gives the hammer less distance to accelerate and limits the valve opening.... As you back the screw out, the hammer accelerates more and has more momentum when it hits the valve.... opening it faster/further.... The hammer is also slightly overlength at the present time.... Once the parts are fitted into the tube I will machine it to length so that it just cocks reliably before hitting the front of the RVA.... The RVA works by adjusting the preload on the hammer spring, of course.... With two variables, there are lots of possibilities to adjust the hammer strike.... They interact, of course.... but it will be interesting to find out how each adjustment affects the performance and the shot to shot consistency....

Bob


Hi..
The power adjuster on the Infinity works like that ..adjustable fall/stroke
length of the hammer....but it is in 2 sections that screw togeather & can be adjusted with a noob/wheel in front of the trigger...wined the two sections closer together..more stroke/power & apart less stroke/power.
Gives adjustment from 400fps to 1220fps with 14.5g pellets..
its got 3 marked setting....but it can have 10 / 20 if yer turn the adjuster in small enough segments.

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PostPosted: Wed Feb 02, 2011 9:15 pm Reply with quote
rsterne
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How does the knob adjust the length without causing drag on the hammer?.... If you can supply a photo of the mechanism someday I would love to see it....

Many guns also use an adjustment to choke off the transfer port.... My Hayabusa will have that as well, built into the breech.... In the Marauder it is built into the valve....

Anybody know how the power is adjusted in the Air Arms rifles?....

Bob

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PostPosted: Wed Feb 02, 2011 9:41 pm Reply with quote
kanyon
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rsterne wrote:
How does the knob adjust the length without causing drag on the hammer?.... If you can supply a photo of the mechanism someday I would love to see it....

Many guns also use an adjustment to choke off the transfer port.... My Hayabusa will have that as well, built into the breech.... In the Marauder it is built into the valve....

Anybody know how the power is adjusted in the Air Arms rifles?....

Bob


hi..
the front section of the hammer is bascly a long gear.... the adjusting wheel is also a gear..but the teeth look like they are there for grip.
So turn the wheel and it turns the front section of the hammer..
possably a bit of drag there...but they are lose in there mesh...
is also a gear.... the rear section of the hammer must have a key/tab
to stop it rotateing with the front section....
Never had a reason to take it all apart....

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Hatsan mod 75 .22
Hatsan mod 99 .177 (Quattro & SAS)
Kral underlever .177


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PostPosted: Wed Feb 02, 2011 9:51 pm Reply with quote
rsterne
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Ahhhhhhhh.... I understand.... What is the total travel of the power wheel?.... You said 3 positions, so I get the idea it moves less than one turn.... Must be larger than the hammer and have pretty coarse thread on the hammer to get enough length change for that range of power, I would imagine....

Bob

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New Old Project - Hayabusa PCP - Mark III Version 
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