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 Post subject: Re: Chip of the day...
PostPosted: Tue Jan 31, 2017 1:28 pm 
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Location: P.G. B.C.
You guys blow me away!

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 Post subject: Re: Chip of the day...
PostPosted: Tue Jan 31, 2017 1:50 pm 
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Joined: Sun Apr 13, 2014 9:14 pm
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Location: Mississauga, ON
A question: What the fudge IS this thing, what is it used for, and how does it work? (I guess that is three questions...)

So far all I have seen is "gas booster" and "air brake driven". :? :?

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Daisy 953 * QB78D * Walther 1894 * Beretta CX4 & PX4 * Zoraki HP01 * Beeman P17 * Walther CP88 Comp. * Crosman 1377/2240/SA6/357-8
Swiss Arms P92 * Colt Commander 1911 * Walther PPK * P08 * Colt Python 357 * TW 1911/Limited * S&W M&P R8


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 Post subject: Re: Chip of the day...
PostPosted: Tue Jan 31, 2017 2:58 pm 
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Primary use as far as airguns go is for filling a pcp from a bottle that has run down in pressure.

ie....You have a pcp that takes a 200bar fill, but your scuba tank has fallen to 1500 psi. You either take it back half full and pay for a fill...full price for a half fill in reality. Or you can use a gas booster to boost that 1500psi and fill your rifle to the full 200bar.

Using a booster, you'll be able to utilize your scuba tank until it falls below about 500psi.

Applies to whatever gas you choose to run your pcp on...air, N2 or He.

How it works;

The brake chamber has a diaphragm in it with 30in2 area. If you apply 100psi to that diaphragm, you can generate 3000lbs of force. You use that force to drive a smaller piston that compresses the gas from your fill bottle. Can generate ~3000psi when driving the brake chamber with ~80psi.

Al


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 Post subject: Re: Chip of the day...
PostPosted: Tue Jan 31, 2017 6:10 pm 
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Oh, I see.

(nadda) :roll:

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 Post subject: Re: Chip of the day...
PostPosted: Tue Jan 31, 2017 6:22 pm 
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Al how long would it take to fill a small 90ci tank or how long will it take to fill a pcp to 200bar

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 Post subject: Re: Chip of the day...
PostPosted: Tue Jan 31, 2017 8:25 pm 
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Depends on the feed pressure.

Some results from the first one I made;

"Feeding the booster 1000psi from my N2 setup, it fills the reservoir of my AT44 to 200bar in 12 strokes. Feeding 1500psi fills to 200bar in 6 strokes. These were from empty, but the feed pressure bleeds through the checks and pre-fills the reservoir and lines to the feed pressure less cracking pressure of the discharge check.

Feeding it 100psi is WAY too slow to be practical, but it WILL top up the AT44 (100bar to 200bar)...in 5-6 minutes. "

Al


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 Post subject: Re: Chip of the day...
PostPosted: Tue Jan 31, 2017 9:54 pm 
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Thanks for the explanation, Al. One more question - what "motivates" it? Is it something you pump manually or is it motorized somehow?

Actually, I believe I saw a video of something like this... if I recall correctly there was two tanks and the pumping was done by switching a valve back and forth?

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Daisy 953 * QB78D * Walther 1894 * Beretta CX4 & PX4 * Zoraki HP01 * Beeman P17 * Walther CP88 Comp. * Crosman 1377/2240/SA6/357-8
Swiss Arms P92 * Colt Commander 1911 * Walther PPK * P08 * Colt Python 357 * TW 1911/Limited * S&W M&P R8


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 Post subject: Re: Chip of the day...
PostPosted: Tue Jan 31, 2017 10:29 pm 
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Here is the original inspiration....might help explain how it is supposed to work.

https://www.youtube.com/watch?v=Kc8RfkDSbfE

Al


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 Post subject: Re: Chip of the day...
PostPosted: Wed Feb 01, 2017 7:50 pm 
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Some preliminary test results for the booster. Stroking the booster by sticking the air hose (regulated) into the feed port for the diaphragm and feeding high pressure side from my regulated N2 bottle. Filling a 13cuin 3000psi Ninja tank from empty. As with the other booster, the feed pressure from the N2 will flow through the head and equalize the bottle to that amount before pumping starts.

Feeding 500psi took 38 strokes

1000psi took 17 strokes

1500psi took 7 strokes.

Have a couple small tweaks to make and then test the heck out of it for a bit. :)

Al


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 Post subject: Re: Chip of the day...
PostPosted: Thu Feb 02, 2017 12:17 am 
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Location: Coalmont BC
Sounds great, Al.... 8)

Bob

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 Post subject: Re: Chip of the day...
PostPosted: Sat Feb 25, 2017 10:22 pm 
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Have around 10hrs on the booster now and decided it was time to tear it down for inspection.

To keep parts count (and costs) down, the cylinder was made from mechanical tubing. Short version? With only 10hrs on it, the orings have visible wear (still working...just showing wear) and the aluminum piston is scuffing despite a close tolerance and lubrication.

Not satisfactory IMO. Could live with it for my own use, but couldn't send that out with a clear conscience.

Decided to tear down the old booster to check on it. It's been in use for about 4 yrs now and has seen a good bit of use. Didn't track the hrs though.

Some minor rub marks on the piston rod (induction hardened and chromed) and brass sleeve and the lube has dried up a little (used silicone grease). Other than that, even the old 70d buna seals are still in good shape. Was a good design, but parts count is high and considerable time to make the parts. Would be prohibitively expensive to produce.

Back to the drawing board on the cylinder and piston...need something in between the two. Current cylinder head design is spot on...so at least something good came out of the current version.

More chips coming.... ;)

Al


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 Post subject: Re: Chip of the day...
PostPosted: Sun Feb 26, 2017 12:02 am 
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Location: Eastern Townships
I know it's more expensive than aluminium, but would bronze-aluminium alloy be suitable for the piston?

Very nice and clean work, BTW! :)


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 Post subject: Re: Chip of the day...
PostPosted: Sun Feb 26, 2017 1:48 am 
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Scrubbing the seals along the bore is the issue. Could work with micro hone tubing and changing seals, but hard to find in 1" x 1.5" and very $$$$. Was quoted $100/ft in a 10' length.

Trying to source some 1 x 1.25 bronze tube.

Al


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 Post subject: Re: Chip of the day...
PostPosted: Wed Mar 01, 2017 10:58 am 
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Joined: Sun Jan 17, 2016 1:38 pm
Posts: 113
You've probably considered this, but how about a wear ring or two? Thinking about my experience rebuilding hyd/pneu cylinders, only time i've seen o-rings actually wear was when the wear ring was no longer keeping the piston centered.


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 Post subject: Re: Chip of the day...
PostPosted: Wed Mar 01, 2017 12:21 pm 
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Had indeed considered wear rings. Major issue with the orings wearing is IMO, the surface finish on the id of the mechanical tubing.

Thinking the plate from the brake chamber is not welded 100% square to the push rod from the factory and is applying some side force to the piston. Wear rings might help in the short term, but it'll still eat itself.

Could try a one piece piston/rod as on the first booster....would guarantee everything centered and "true", but doesn't fix the bore surface finish.

Have the re-design done in cad, sourcing materials at the moment.

Al


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