New Old Project - Hayabusa PCP - Mark III Revisited



Author Topic: New Old Project - Hayabusa PCP - Mark III Revisited  (Read 67889 times))

Offline rsterne

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Re: New Old Project - Hayabusa PCP - Mark I Revisited
« Reply #240 on: March 31, 2018, 10:44:24 PM »
I made the .25 cal transfer port today and reassembled the Hayabusa Mk.I with the original QB hammer spring and RVA.... I thought it was regulated at about 1900 psi, BUT IT TURNS OUT IT IS ONLY AT 1750 PSI, and here are the results with the 25.4 gr. JB Kings and 34.0 gr. JSB Heavies....



I gained about 40 fps with the larger porting with the 25.4 gr. pellets, so it was well worth doing.... The QB Spring just touches the inside of the hammer at 3 turns out from maximum, so I should be able to make an effective SSG using that spring on a guide with some preload and a bit of a gap.... That will be the next project.... The cocking force on the knee of the curve is high but acceptable.... with an SSG it will be more constant and "feel" lighter because all the load won't come on at the end of the stroke.... I may use a longer lighter spring, I'll see what I have around that might be even better than the QB spring....

Bob
« Last Edit: April 04, 2018, 01:21:06 PM by rsterne »
  • Coalmont, BC, Canada
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), .22 QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Bench PCP, 6mm Regulated PCP and .257 Unregulated, Two BRods.

Offline rsterne

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Re: New Old Project - Hayabusa PCP - Mark I Revisited
« Reply #241 on: April 02, 2018, 07:42:06 PM »
I built an SSG for my Hayabusa Mk.I today.... I used a 7/16" x 20 NF hex head bolt 1" long for the gap adjuster, and drilled it out to 13/64" for a 3/16" steel guide rod.... The rod I threaded both ends to 10-32 thread, on the inside I loctited on a nut and turned it down to 0.35" OD with a rounded end to fit inside the hammer, and then slid on a 1/4" plastic tube 1-1/4" long for a spring guide spacer, and at the other end an O-ring bumper and two 10-32 nuts locked against each other for preload adjustment.... The mount was turned from a piece of 1" OD 2024-T2 barstock, drilled and tapped for the adjusting bolt.... The hammer spring is 3.0" long x 0.36"D x 0.049" wire, with a rate of 13 lb/in.... Here is what it looks like....



I set the preload to 0.40" (5 lbs.), adjusted the SSG gap so that the end of the guide just cleared the inside of the hammer for my "Zero" gap point, and then shot a 34.1 gr. King through the Chrony at each gap adjustment to 8 turns of gap (0.40").... I then chose three settings on the knee of the curve and shot one 8-shot group at each setting, recording the starting and ending pressure on the 22 CI bottle (using a digital gauge) for each string so that I could calculate the efficiency.... Here are those results....



I then kept on shooting the gun down until I saw the plenum pressure gauge on the downstream side of the regulator start to move, checked the velocity and it was still the same, and actually shot down another 150 psi without any velocity loss with 5 turns of gap.... By that time I was down to 1600 psi, so I topped up the bottle until I saw no more movement on the plenum gauge, and determined that the regulator setpoint is only about 1750 psi, not the 1900 psi I thought previously.... That explains why the velocity plateau was only 960-970 psi, when I expected a bit more....

You will note that the FPE/CI increases from just 1.01 at 945 fps to 1.23 at 930 fps and 1.48 FPE/CI at 895 fps.... I want to raise that entire range upwards by about 30 fps, so I plan to drain the bottle and reset the regulator to 1900 psi.... I should still have lots of adjustment using this same hammer spring.... and the cocking effort is a bit less than previously without the SSG.... One thing I noticed during the 8-shot strings was that the ES was quite low on the knee.... 12 fps on the 945 fps string and only 6 fps on the 930 fps string, but increased to 18 fps on the 895 fps string.... It is not uncommon to see the ES increase when the SSG gap gets larger, and you start to get down on the downslope part of the velocity curve.... all the more reason to run a regulated PCP right on the knee of the curve....

Bob
« Last Edit: April 02, 2018, 08:20:09 PM by rsterne »
  • Coalmont, BC, Canada
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), .22 QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Bench PCP, 6mm Regulated PCP and .257 Unregulated, Two BRods.

Offline Hobbyman2007

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Re: New Old Project - Hayabusa PCP - Mark I Revisited
« Reply #242 on: April 02, 2018, 09:23:14 PM »
Nice work on the SSG Bob. Gives me an idea why Iím getting inconsistent velocities from one of my .25 builds . Iím going to add a plastic sleeve to the spring guide .😀
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Offline rsterne

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Re: New Old Project - Hayabusa PCP - Mark I Revisited
« Reply #243 on: April 02, 2018, 11:12:50 PM »
The plastic sleeve only keeps the spring straighter.... You could use a 1/4" diameter steel rod and get the same results.... but the guide would then be 77% heavier.... I made the sleeve about the same length as the spring at coil bind....

The biggest reason for inconsistent shot-to-shot velocities in a PCP is that any small variation in hammer strike can cause a difference in the valve lift and dwell.... especially when the pressure is higher than where the velocity peaks.... This occurs in an unregulated PCP between the fill pressure and the peak velocity.... and in a regulated PCP that is tuned on the downslope of the curve.... The velocity is much more stable, shot-to-shot, on the back half (low pressure side) of the bell curve in an unregulated PCP, which is like a regulated gun tuned up on or near the plateau.... It is unfortunate things work out this way, because it means that efficient tunes tend towards a higher ES....  ::)

Bob
« Last Edit: April 04, 2018, 12:14:05 AM by rsterne »
  • Coalmont, BC, Canada
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), .22 QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Bench PCP, 6mm Regulated PCP and .257 Unregulated, Two BRods.

Offline rsterne

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Re: New Old Project - Hayabusa PCP - Mark I Revisited
« Reply #244 on: April 04, 2018, 12:11:24 AM »
I confirmed that the setpoint was only 1750 psi, so I bumped up the regulator to 1900 psi today.... I used my "tiny" tank to test for the plateau curve and check for leaks, and here are the results....



With the higher setpoint, I can barely reach the plateau with zero SSG gap with the 34.1 gr. King Heavies, which is exactly the way I like it.... This places my usable tune at a couple of turns of gap, and I like keeping the gap small for better consistency in the hammer strike.... With the 25.4 gr. Kings, the plateau starts at about 2 turns of gap, with the mid 900s occurring at about 5 turns out.... Using those pellets is only a secondary consideration, the whole point of this series of mods was to increase the power to make the 34.1 gr. Heavies into the mid 900s, which I have now done.... After I replace the 22 CI tank tomorrow, I will do some efficiency testing to compare the higher setpoint to the old one.... I hope to also do some testing with the .22 cal barrel fitted....

Bob
  • Coalmont, BC, Canada
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), .22 QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Bench PCP, 6mm Regulated PCP and .257 Unregulated, Two BRods.

Offline rsterne

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Re: New Old Project - Hayabusa PCP - Mark I Revisited
« Reply #245 on: April 06, 2018, 05:44:43 PM »
I put the .22 cal upper on the gun today and plotted out the plateau, knee and downslope curve with the 18.1 gr. JSB Heavies and the 25.4 gr. JSB Redesigned Monsters.... Here are the results....



Running wide open the gun is now capable of driving the 18.1 gr. Heavies Supersonic....  :o 

I installed the 22 CI bottle (360 cc) and tested some SSG gap settings on the knee of the curve and settled on 5 turns out as the best compromise with the 25.4 gr. Monsters.... I got an average of 940 fps (50 FPE) at an efficiency of 1.04 FPE/CI, and I was able to shoot all the way down to 1600 psi before the velocity dropped below 930 fps.... That is 300 psi below the setpoint, which should give me a total of about 45 shots per fill at 50 FPE.... I think that pretty decent for a .22 cal at that power level which is basically a detuned .25 cal, but I think that using a bit lighter hammer might improve the efficiency even further, while reducing the SSG gap somewhat, which is desireable.... If I wanted to use the 18.1 gr. Heavies I could back out the SSG to about 6.5-7 turns of gap to shoot them in the mid 900s.... but I would get way more shots if I dropped the regulator setpoint to below 1600 psi.... I'll reinstall the .25 cal upper and do a similar test with the 34 gr. King Heavies soon....

Bob

« Last Edit: April 06, 2018, 08:58:16 PM by rsterne »
  • Coalmont, BC, Canada
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), .22 QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Bench PCP, 6mm Regulated PCP and .257 Unregulated, Two BRods.

Offline rsterne

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Re: New Old Project - Hayabusa PCP - Mark I Revisited
« Reply #246 on: April 08, 2018, 03:50:01 PM »
I reinstalled the .25 cal. barrel on my Hayabusa Mk.I. today, set the SSG at 2 turns of gap, and took 8 shots to check the efficiency.... The average velocity was 953 fps, with a high of 955 and a low of 948 (0.8% ES) for 69 FPE and a drop in the 22 CI tank of 320 psi.... This works out to 1.13 FPE/CI, which is OK for the power level attained.... By comparison my unregulated Hatsan AT-44 S10 Long with the same pellets had the same average velocity, but the ES was twice as great at 1.7%, for 9 shots from 2750 psi down to 2250, an efficiency of 1.25 FPE/CI.... As is typical for a regulated PCP at high power, you give up a bit of efficiency (because of the lower pressure, in this case 1900 psi).... but get a lower ES and gain in shot count.... The gun as configured should be about 27 shots to the setpoint, and possibly about 35 down to 1600 psi, which is where the .22 cal velocity started to drop off.... Relative to the caliber, the tunes are similar, 50 FPE in .22 cal and 70 FPE in .25 cal.... I think this is a good place to leave the Mk.I. until I get a chance to shoot it at distance and see how it likes the new heavier pellets....

Bob
  • Coalmont, BC, Canada
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), .22 QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Bench PCP, 6mm Regulated PCP and .257 Unregulated, Two BRods.

Offline rsterne

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Re: New Old Project - Hayabusa PCP - Mark III Revisited
« Reply #247 on: December 02, 2018, 11:13:22 PM »
Now that I have some shop time with no major projects on the go, I decided it was time to revisit the Hayabusa Mk.3 version, which is a .410 shotgun and .457 rifle.... Ever since the SS Valve came on the scene, I have been itching to make one for this big-bore, as it REALLY needs it.... The gun uses a 1/2 lb. hammer with 2" of travel, and it takes over 28 lbs. of cocking force.... If there was ever a gun that needs a reduction in hammer strike and cocking force, this it it....  ::)

I pulled the gun completely apart, had a look at what I was dealing with, and started with the new valve internals.... I scaled up my SS valve to use a PEEK poppet with a 1/2" big end and a 5/16" small end.... The thimble is turned from a piece of 5/8" 1144 Stressproof, and after drilling and then finishing the bores with end mills and sandpaper, I turned the outside down to 9/16" at the back and 3/8" at the front.... I turned the poppet from a piece of 1/2" PEEK rod, drilled it for a 1/8" stem and a 0.040" bypass vent, and pressed it onto the valve stem with some Loctite 638 for good measure.... The last step was to turn the O-ring grooves, working gradually deeper until I had a nice slide fit and the valve spring would reset the poppet.... Here is what it looks like, along with the original parts....



The original valve was just a rear half, there is a long pedestal inside the reservoir for a spring seat.... not an elegant arrangement, but it did unshroud the poppet completely.... I will have to make a complete valve body for the SS Valve, because it has to mount the thimble.... The exhaust port is 3/8" (0.375") and the throat is 13/32" (0.406"), and the original poppet OD was 0.453".... At 3600 psi, the force holding the valve closed was 580 lbs.... With the new SS valve, it will only be 280 lbs., less than half.... I will use either 27/64" (0.422") or a full 7/16" (0.437") for the throat in the new valve, as either will work with the new larger (0.500") poppet.... Next up is to figure out how to make a new valve body to mount everything inside....

Bob
« Last Edit: December 03, 2018, 02:03:49 AM by rsterne »
  • Coalmont, BC, Canada
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), .22 QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Bench PCP, 6mm Regulated PCP and .257 Unregulated, Two BRods.

Offline rsterne

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Re: New Old Project - Hayabusa PCP - Mark III Revisited
« Reply #248 on: December 05, 2018, 10:02:03 PM »
I continued working on the valve yesterday and today.... I got the body bored out inside, with a shoulder for the thimble mounting wheel, and a groove for the retaining circlip.... Then I made the perforated wheel that mounts the thimble.... Here are those parts....



The total area of the eight 3/16" holes is twice that of the 3/8" transfer port.... The valve is bored out to nearly 7/8", which gives an annular gap of 0.150" around the thimble, so that area is three times the area of the transfer port.... You can see the 1/16" vent hole in the thimble mounting screw.... As usual for my SS valves, there is a collar on that screw so that I can tighten it against the end of the thimble without having the thimble mounted rigidly to the wheel.... In fact, the hole is oversize, so that the thimble can align itself with the poppet to prevent any binding....

I also drilled and tapped the 10-32 mounting holes, machined the O-ring groove, and milled out the huge exhaust port.... I machined this a bit differently than I have done before, and I really like the way it turned out.... I did a 1/2" flat for the transfer port, and then ran a 3/8" ball end mill in until the center was just past the flat.... I then used a 5/16" end mill, tilted on a 25 deg. angle towards the valve seat, and milled through to the throat.... I moved the mill sideways in the hole until the width of the port was the full 3/8", and fore and aft until it just touched the front and back of the 3/8" hole.... I then removed the valve from the milling attachment, and finished it with a spherical burr on my Dremel.... I recently purchased some adjustable hole gauges, and I set the diameter to 3/8", and after grinding away any steps inside the port, I kept checking it and grinding the restrictions until the exhaust port was at least 3/8" everywhere.... Here is a photo of the valve with the gauge in place, and the thimble mounted in the perforated wheel....



This photo shows how massive the exhaust port is, with the adjustable gauge beside the valve, for those of you that have never seen one....



The main tube had a bit of rust on it, so I polished it down and re-blued it with Van's Cold Blue.... I then lapped the poppet to the seat until it appeared to seal, and then reassembled the main tube, using my "mini-tank" instead of the 500 cc bottle, in case there are any leaks.... I filled it to 3000 psi, and it appears to be holding.... I will leave it overnight before working on a new hammer and spring, because I think (hope) the old one will be way to much for this replacement SS valve....

Bob
  • Coalmont, BC, Canada
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), .22 QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Bench PCP, 6mm Regulated PCP and .257 Unregulated, Two BRods.

Offline rsterne

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Re: New Old Project - Hayabusa PCP - Mark III Revisited
« Reply #249 on: December 07, 2018, 07:39:07 PM »
I made an SSG assembly yesterday, using two 2.5" long x 0.48" diam. springs made from 0.051" wire.... They have a rate of 10 lb/in, but when you stack two inline that drops in half, to just 5 lb/in.... I had to make a spacer that runs on the guide rod to keep the ends aligned, and after the springs were set, they lost 0.1", but the spacer replaced that, so the total spring length was 5.0".... I set the preload to only 1/2" (2.5 lbs.) and assembled the gun, with the adjuster backed off all the way, so the 2" hammer stroke was reduced to only about 1.25".... The resulting roar brought my wife out to the shop to see if I was OK, and I just explained to her that the machine gun she heard was an example of runaway hammer bounce....  :o

Step two was to make an MDS hammer to the same dimensions as the steel one, which reduced the weight from 165 gr (237 gr. with the original guide and cocking handle) to just 24gr. plus the cocking handle, so the hammer dropped to 48 gr. or just 20% of its original weight.... At zero gap the gun fired with an anemic "pop", so I knew I was going to have to end up some place in the middle.... So much for yesterday....  ::) Ö. The really exciting part is that the cocking force is a fraction of what it used to be.... This SS Valve REALLY works....  8)

This morning I machined away as much of the original steel hammer as I could, and at the same time moved the cocking notch back 1/2" to reduce the hammer stroke to 1.5".... The hammer was down to 82 gr. (half what it started out) plus the cocking handle, for a total of 106 gr.... The gun was beginning to show that it had a chance of being tuned, and I obtained velocity readings just under 820 fps with the 336 gr. Lee FN bullet, which works out to 500 FPE, using a 3600 psi fill of the main tube and mini-tank, which is about 145 cc (less than 0.3 cc/FPE).... That is a pretty anemic plenum volume for a 500 FPE gun, but shows I am likely on track to match the 550 FPE I had before, when I have the 500 cc bottle in place, with 640 cc available to keep the pressure up during the shot cycle....

I ran into a problem when I dropped the action into the stock, the end of the SSG, while cocking, hit the cheekpiece, and wouldn't allow me to cock the gun.... I pulled it out and shortened the guide rod, increasing the preload to 1", and moved the sear notch back on the hammer another 1/4", so I now only had 1.25" of hammer stroke.... This allowed the end of the guide to JUST clear the stock....  Here are the new parts at this stage....



With this set of parts, I was still getting machine-gunning with 1/4" of gap in the SSG, really loud inefficient shots with 3/8" of gap, and workable shots with 1/2" of gap.... The velocity was around 815 fps, with stellar efficiency of about 1.35 FPE/CI.... pretty remarkable at just under 500 FPE.... With the 216 gr. Lee bullet the gun was shooting just over 950 fps at that tune.... Now remember that I had 1" of preload on the spring, and with 1/2" of gap that means the spring was only being compressed a total of 1.75" when fully cocked.... That works out to about 9 lbs. of force, with a 3/4" effective hammer stroke on a 106 gr. hammer.... Yet I was getting similar power (other than the undersized plenum, which was costing me about 10% in FPE) to what I had originally with a 2" stroke on a 237 gr. hammer that took 28 lbs. to cock it.... WOW !!! you can really see what an SS valve can do to reduce the cocking force, even on a big-bore....  8)

I wasn't happy with the 1/2" of gap in the SSG, so I decided to try the MDS hammer again, with the full 2" of stroke and 1" of preload in the SSG.... With the gap set to 1/4" I got the gun to fire properly, but the SSG rod was hitting the stock again.... So, I moved the cocking notch back 1/2" (1.5" stroke) and increased the preload to 1.25", and I got just one "proper" shot, with 1/2 turn of gap on the SSG.... I am learning that this particular SS Valve is acting like a Cothran valve, it is either working or not, with no bell curve.... at least that is how it appears right now.... Then things went south.... The poppet failed, the stem started sliding back in the PEEK, so my testing is over for today, and I have to rebuild the valve....  >:(

I am delighted with how easy the valve is to open, perhaps too easy.... I am not happy with the cycling, which appears to have no bell-curve, not the best for an unregulated PCP, as I won't be able to tune it for a bell-curve.... I think the only solution is that when I rebuild the valve to increase the diameter of the front portion of the poppet.... This will make the valve harder to open, but hopefully will make it tuneable.... I just hope that my current hammer can be made to work after I change the valve.... Plus, I have to figure out why the stem backed out, I think it is likely because of the air pressure in the center chamber, between the O-rings, may have worked its way around and be pushing on the front end of the stem (with a force of about 40 lbs. at 3600 psi).... The autopsy showed the stem had slid back about 1/4"....  ::)

Bob
  • Coalmont, BC, Canada
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), .22 QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Bench PCP, 6mm Regulated PCP and .257 Unregulated, Two BRods.

Offline Motorhead

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Re: New Old Project - Hayabusa PCP - Mark III Revisited
« Reply #250 on: December 08, 2018, 12:20:03 AM »
Wish to stop the jack hammering bounce ? ...... Jet DOWN the cobra chamber & get the free flight gap under .100"

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Offline rsterne

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Re: New Old Project - Hayabusa PCP - Mark III Revisited
« Reply #251 on: December 08, 2018, 01:22:21 AM »
but first of all, I have to get in the ballpark with the hammer strike.... Way too light or way too heavy won't cut it, just like with a conventional valve.... except the margin of error is less with a valve that is this easy to open, yet expected to deliver over 500 FPE....

Incidently, the jack hammering bounce was far worse with a smaller SSG gap, and reduced as I increased the gap.... indicative of too much hammer strike, IMO....

Bob
  • Coalmont, BC, Canada
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), .22 QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Bench PCP, 6mm Regulated PCP and .257 Unregulated, Two BRods.

Offline Motorhead

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Re: New Old Project - Hayabusa PCP - Mark III Revisited
« Reply #252 on: December 08, 2018, 01:50:45 AM »
Incidently, the jack hammering bounce was far worse with a smaller SSG gap, and reduced as I increased the gap.... indicative of too much hammer strike, IMO....
Bob

Or the balance of valves calibration has it "too easy to open"  :o
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Offline rsterne

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Re: New Old Project - Hayabusa PCP - Mark III Revisited
« Reply #253 on: December 08, 2018, 01:58:34 AM »
Yep, I agree, as I stated above, the plan is to increase the diameter of the front of the poppet to 11/32" or even 3/8" from the 5/16" it is currently.... The rear is, of course, 1/2".... All the previous SS Valves I built (from scratch) use a 1/4" front end on a 3/8" back end (67%) and work great.... This valve is only 63%.... I favoured "easy to open" because of the HUGE cocking force required on the conventional version.... I certainly got my wish....  ::)

It may now be a case of "two steps forward, then one step back"....  ;)

Bob
« Last Edit: December 08, 2018, 02:01:45 AM by rsterne »
  • Coalmont, BC, Canada
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), .22 QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Bench PCP, 6mm Regulated PCP and .257 Unregulated, Two BRods.

How do you word it... "Air Guns" or "AirGuns"?