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New Ball Valve Handle

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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New Ball Valve Handle

Unread postAuthor: boyntonstu » Wed May 19, 2010 10:29 pm

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I removed the brass stop and the ball is able to freely rotate.

I made a coupler nut by brazing 2 M8-1.25 nuts together.

The "pulley" consists of 3 fender washers epoxied together with JB Weld.

The inner fender washer is slightly smaller in diameter.

The 1/4 pulley circumference is slightly over 1".

If my 50 pound crossbow can pull a string wrapped around the pulley at about 100 fps, the ball valve will open in 0.001 second.

That is my goal.
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Unread postAuthor: Technician1002 » Wed May 19, 2010 10:37 pm

How many revolutions does it have to turn to get up to that speed?

Seriously, what is the effective mass of the moving parts and what is the accelerating force? From there acceleration can be found and time to move 1 inch from a dead stop can be found. 1 ms sounds optimistic, but it may be possible. With the brass body and induced currents (shielding) the magnet in the valve method of measurement wont work with the magnet inside the valve. A magnet on the pulley with a pair of pickup coils is an alternative location. I would be interested in your measured and calculated opening time.
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Unread postAuthor: boyntonstu » Wed May 19, 2010 10:47 pm

Technician1002 wrote:How many revolutions does it have to turn to get up to that speed?

Seriously, what is the effective mass of the moving parts and what is the accelerating force? From there acceleration can be found and time to move 1 inch from a dead stop can be found. 1 ms sounds optimistic, but it may be possible. With the brass body and induced currents (shielding) the magnet in the valve method of measurement wont work with the magnet inside the valve. A magnet on the pulley with a pair of pickup coils is an alternative location. I would be interested in your measured and calculated opening time.


With a Casio EX FS-10 camera at 1000 fps I should be able to directly view and measure the ball opening time.

I am shopping for one now an they are at about $130.

http://www.exilim.casio.com/products_exfs10.shtml
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Unread postAuthor: Technician1002 » Wed May 19, 2010 11:22 pm

Only $130? I thought they were considerably more expensive. I just assumed they were over $600. I'll have to keep my eyes open for one. It would, at twice the price of a shooting chrony, be much more useful.

Just a quick note, if the valve indeed did open in 1MS, that camera is too slow. It would fully open from one frame to the next. The frames are 1ms apart at the fastest 1,000 frames/sec speed of the camera.

Somehow I doubt the valve can be that quick.
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Last edited by Technician1002 on Thu May 20, 2010 1:30 am, edited 1 time in total.
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Unread postAuthor: MrCrowley » Thu May 20, 2010 12:59 am

Couldn't an audio chronograph help find the opening time? There would be a small hiss before a bang (assuming the chamber is large enough I guess). Just an idea.
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Unread postAuthor: Crna Legija » Thu May 20, 2010 1:30 am

i think if you give the crossbow your using some weight(just on the string like fishing sinkers) and leave room for it to accelerate then for it to yank the valve open it would be quicker
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Unread postAuthor: Technician1002 » Thu May 20, 2010 1:37 am

MrCrowley wrote:Couldn't an audio chronograph help find the opening time? There would be a small hiss before a bang (assuming the chamber is large enough I guess). Just an idea.


If it opened as quickly as my QDV cannons it would have a sound like them.

The opening sound would be like this.
Image

Telling the opening time from the sound is not easy. When it starts is easy to see, when it is all the way open is hard to define.
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Unread postAuthor: boyntonstu » Thu May 20, 2010 5:37 am

Technician1002 wrote:Only $130? I thought they were considerably more expensive. I just assumed they were over $600. I'll have to keep my eyes open for one. It would, at twice the price of a shooting chrony, be much more useful.

Just a quick note, if the valve indeed did open in 1MS, that camera is too slow. It would fully open from one frame to the next. The frames are 1ms apart at the fastest 1,000 frames/sec speed of the camera.

Somehow I doubt the valve can be that quick.


Somehow I doubt the valve can be that quick.

I have my doubts too, however the goal and the project to attempt it is interesting.

If it can open fast enough to equal a piston valve, it would be a great performer because the chamber to the barrel is a straight 3/4" through the ball.

I have not measured the ball opening ID but I am sure that it opens wider than the seat of a piston valve. No bends, and minimum turbulence adds to its potential performance.

If people say that it can't be done, I usually take the bait.

That's how my $100 trustworthy elevator got built 7 years ago.

http://www.youtube.com/watch?v=_hom61NxuaE

Besides, it gives me an excuse to buy a high speed camera.


"HIGH SPEED MOVIE
Video Capture at up to 1,000 fps

The 1,000 frame-per-second High Speed Movie capabilities of the EX-FS10 is the next evolution of digital imaging. This feature allows you to easily shoot ultra slow-motion movies at speeds that were only available on super expensive, pro-level cameras.

Settings for 210 fps, 420 fps and variable 30-210 fps are included with the camera. While 30-210 fps is selected, you can toggle the movie recording speed between 30 fps and 210 fps, giving you the ability to record at the speed that's right for the moment."

NEW Casio High Speed EXILIM EX-FS10 9.1 Megapixel
Item condition: New, Never Opened
Time left: 14d 03h (Jun 03, 201007:12:26 PDT)
Price: US $138.88 Buy It Now Free Shipping
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Unread postAuthor: chinnerz » Thu May 20, 2010 6:09 am

Only $130? I thought they were considerably more expensive. I just assumed they were over $600. I'll have to keep my eyes open for one. It would, at twice the price of a shooting chrony, be much more useful.

Just a quick note, if the valve indeed did open in 1MS, that camera is too slow. It would fully open from one frame to the next. The frames are 1ms apart at the fastest 1,000 frames/sec speed of the camera.

Somehow I doubt the valve can be that quick.


The deal with cameras is, either they record in higher definition OR they record at a high frame rate.

That Casio is a great deal for a camera which shoots at 1000 FPS,

http://www.cnet.com.au/lg-renoir-kc910-339291601.htm
This LG phone shoots at 120 FPS = almost 5X slo-mo
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Unread postAuthor: boyntonstu » Thu May 20, 2010 6:22 am

chinnerz wrote:
Only $130? I thought they were considerably more expensive. I just assumed they were over $600. I'll have to keep my eyes open for one. It would, at twice the price of a shooting chrony, be much more useful.

Just a quick note, if the valve indeed did open in 1MS, that camera is too slow. It would fully open from one frame to the next. The frames are 1ms apart at the fastest 1,000 frames/sec speed of the camera.

Somehow I doubt the valve can be that quick.


The deal with cameras is, either they record in higher definition OR they record at a high frame rate.

That Casio is a great deal for a camera which shoots at 1000 FPS,

http://www.cnet.com.au/lg-renoir-kc910-339291601.htm
This LG phone shoots at 120 FPS = almost 5X slo-mo


I am looking for accurate data, not high resolution photos.

A thumbnail size would be sufficient for my spud guns.

"i think if you give the crossbow your using some weight(just on the string like fishing sinkers) and leave room for it to accelerate then for it to yank the valve open it would be quicker"

That is worth a try.
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