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Messages - Wingman

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Modifications / Re: munted!!!!!$#%%^%
« on: October 13, 2018, 08:12:50 PM »
I really shouldnt be laughing... but we have all been there... I havent wrecked anything tonight but still having a whisky  ;D

General Discussion / Re: Proposed Tahr Cull
« on: September 28, 2018, 05:25:59 PM »

Hunting / Re: Controlling Canadian geese
« on: September 17, 2018, 06:27:19 PM »
Controlling larger numbers of any pest is best done with a little "pre-site prep" and a single shot from a safe distance...

Hunting / Re: 6 Pointers for Pauly5
« on: August 28, 2018, 08:05:41 AM »
Once again.. the law states it is illegal to have a loaded FIREARM in a vehicle.. no mention of airguns so totally legal practice  regardless of personal opinion. Well done Hidayat..

Modifications / Re: PCP pistol build challenge.
« on: August 02, 2018, 07:46:09 PM »
Great to have another member in the build. If you need anything just ask we will try to help.

Not a lot of workshop time happening for me..  I did knock up a quick brass transfer tube and cut the  counter bores in the breech and valve to seal the O rings on.

Modifications / Re: pcp air tube material
« on: August 02, 2018, 06:15:37 AM »
While the yield and tensile strength is ok the wall thickness is too thick. Material of that dia only needs 3mm walls.
Dont forget that safety factors dramatically dive with plug designs.. threading or pinning plugs will always be the weaker part of the build due to the way the pressures act in a cylinder.
At any given pressure the load on the end plugs is twice that of the load trying to split out the side of the tube.

Ulrich Aluminium  sell 31mm x 3mm, 32mm x 3mm and a 32.2 x 3.2mm in from memory 6360 T5 (Call them to confirm) and is a suitable tube.

Wakefield metals also do an imported 6061 T6  1"ID with 1/8" walls that is suitable.

Aviation suppliers can get you the 7075 T6 in that same size but its not cheap or you can get Titanium off aliexpress which is made by Snow peak in China, the second largest Titanium supplier besides India. Most of the Ti available in usa comes from China or India.

Hunting / Re: LED Spotlight vs HID spotlight
« on: August 01, 2018, 05:52:39 PM »
ahhh. the central north island wallaby!

But that's possibly as much my eyes deteriorating

Im convinced it is... those central north wallabies are although large, are common maize eating hares

General Discussion / Re: Legal action.
« on: August 01, 2018, 10:21:58 AM »

Hunting / Re: LED Spotlight vs HID spotlight
« on: August 01, 2018, 10:12:45 AM »
I totally agree Akzle, I have tried LEDs in the past and find they dont have the same success rate as my trusty ol 100w 12v halogen spotty. I think in some cases the brighter white light of leds have the critters looking away or spook quicker.. I run a small gun mounted LED Ultrafire torch for close or finishing shots but all my spotting is done with the trusty old halogen now.

Modifications / Re: PCP pistol build challenge.
« on: July 25, 2018, 02:08:52 PM »
HSS and a bench grinder. white wheel. toolmaking is an art in itself, but if you run old gear (i know you have some new flash CNC aircraft grade stuff) it's invaluable, and there isn't much you cant form up.

I still run a lot of HSS too and make plenty of tools with it for oddball jobs etc

Modifications / Re: PCP pistol build challenge.
« on: July 24, 2018, 06:50:39 PM »
No you are right, not a lot of machines needed but I have a massive amount of tooling, taps dies, milling cutters, chambering tools, std and long series drill bits, center drills, countersink bits, throat cutters, hole cutters, dovetail cutters, end mill cutters, ball nose cutters, knurling tools, cut off tools, turning cutters etc etc.. they all add up and you always seem to need a size or type you don't currently have.. Id say the tooling I currently have adds up to way more than what the machines that run them arte worth.

Anyway the little pistola tube passed its 24 hour 4500psi leak down test and is now doing another 24hour low pressure leak down test at 1500psi because they are more likely to leak at low pressure than the higher pressures due to less force on the poppet valve and rubber O rings seating them tightly.
No bubbles in 6 hours so Im quietly confident.

General Discussion / Re: Legal action.
« on: July 23, 2018, 05:35:25 PM »
Whatever the Police are doing, I am sure they have the best of intentions.

Say what? That is something only a policeman would say.

Akzle you nailed it.

Whoever appeals to the law against his fellow man is either a fool or a coward.
Whoever cannot take care of them selves without that law is both. Randy Blythe

"They are tasked with a job (POLICY Enforcement) from their employer (the crown)"

It is these policy makers from the EU etc that NZ police and government are getting the pressure from to disarm the public.
From my personal dealings and observations, those 60% in the job to "do good" ( or the ones with the brains to observe) leave the force within a few years from either seeing they fight losing battle due to at best, a pathetic justice system or they see the police force for what it is, a limited liability company run like a gang.

No amount of change to gun laws will ever change the fact the criminals dont care about the laws to begin with and will always have guns. Just take a look at the UK and Australia as a model.. disarm the law abiding and now only the criminals have guns.

Modifications / Re: PCP pistol build challenge.
« on: July 21, 2018, 08:41:04 PM »
Another couple of hours in the shed today and a little more progress.
I drilled and pinned the valve in and decided to move the transfer port as far to the back of the valve as possible to get an extra inch of usable barrel.
This meant the valve had to be angle drilled  back to the transfer port.

I also pressed in a brass sleeve to keep the valve running silky smooth.

The front plug was bored with a ball nose cutter not only to claim back a few cc but the dish helps reduce the hoop stress on the end plugs over a flat surface. I then cut a small flat for the inlet valve O ring to seal on.

Lastly I have roughed put a breech from some 20mm alloy round bar.
Ill be making some open sights for this one so I milled the top flat and didnt bother with cutting a dovetail.

Modifications / Re: PCP pistol build challenge.
« on: July 21, 2018, 10:30:54 AM »

Phil you know how am using 4x 6mm grub screws rather than the cap screws with heads in shear and
 tho have machined most the socket off i am still bit leary bout grub screws in this softer material and
 have pressure tested cylinder up to 3500 psi as couldnt go ant higher,i did leave it pressured for 5 days
 everything looked good,but still not fully comfortable with this method in alli tubing eh!!
 would like test a cylinder to much higher pressures before was really comfortable.
 only 1 inch tubing but can still use your method,do you think i should change mate??i got very healthy
 respect for the pressures we using,rather be safe than sorry eh!!
 cheers mike

For the material size and grade your four 6mm screws are adequate to hold back your lower fill pressures.  In the pinned design, the retaining bolts distance to the edge of the material is more important.
When using the smooth cap screw head in shear method in titanium, duralumin, aluminium 2024 T3, 6061 T6., 6063 T5 and 7075 T6  "1.5 D" (one and a half times the pins diameter from the center of the hole to the edge of the material in both plug and tube is adequate to stop them tearing out the end of the tube material. With a threaded hole Id be tempted to push that closer to 2D.

I tend to over engineer every vessel I make as my PCPs get high use meaning lots of fills and empties equating to more material expansion and contraction cycles and heat stress in a shorter time. All alloys have a cycle life. Also all my fill gear and other PCPs are 300bar (4500psi) so my builds need to be the same.
I hydro tested one of my bullpup builds in the same spec you see here to 9200psi with no permanent stretching or damage so feel quite comfortable filling to 3000psi or if I should have a brain fart and accidently fill to 4500psi the cylinder will handle it fine. I have never done a destruction hydro test on my builds but Id guess they have a safety factor of at least 4 times standard working pressure.
The weakest link in this design (like most) is the plug o rings which would fail at high pressure causing a fairly slow and anticlimactic leak down rather than lateral tube split explosion or radial thread separation in threaded tube builds.
I have seen pneumatic destruction tests done on steel tubes with much smaller cap screws that did shear off one by one until the plug moved which broke the O ring seals and dumped the air faster than it could be replaced but the plug was still retained in place by the damaged screws. This is another reason I prefer to build with the pinning method.

Unfortunately as you get into the smaller 1" tube like yours are limited for cap screw size and depth before you breach the valve ports or the fill valve if it in the front plug.
As you know the smaller the tube dia the less the material stress and the less plug retention you need but there is a compromise with lower safety factors which along with larger air storage capacities (shorter pistols and rifles) is why I prefer the larger tube diameters with thicker walls. 
If I did use 1" tube Id personally be threading the front plug in and probably use a single large off center pin in the lower rear of the valve (see pics) and incorporate the breech screws into the top of the valve for added strength.

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