Recent Changes

Saturday, January 10

  1. page Blazer Game edited ... Most Creative: Camas Valley School, Camas Valley Overall Winner: Arlington High School, Arlin…
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    Most Creative: Camas Valley School, Camas Valley
    Overall Winner: Arlington High School, Arlington
    The Video from the Trailblazers is posted on youtube here.
    http://www.youtube.com/watch?v=W2kOs_HDIdg

    For Creativity, Camas Valley School won with their pistol that would make Clint Eastwood proud. Unfortunately due to regulations regarding weapons, they had to cover their great design. It would have been a great display of the second amendment. It was a great job and shot well.
    Camas HS is featured in The News-Review newspaper. I have received permission from the photographer DD Bixby to post the photos here. The story in The News-Review by DD Bixby is here.
    (view changes)
    8:56 pm

Tuesday, December 23

  1. page Barrel length trim method edited ... Results I assumed the higher velocity would provide lots of voltage from the high speed. To s…
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    Results
    I assumed the higher velocity would provide lots of voltage from the high speed. To save wire the coils were drastically reduced in the number of turns. As a result the initial tests failed to trigger the scope and produce a graph. Grr.. Knowing the signal was there, but too low in amplitude, I knew I needed to either re-wind the coils, or amplify the signal. I had a disk jockey style mixer floating around so I grabbed it and used it to pre-amp the coil by feeding it into the microphone jack. It worked like a charm. After tuning the launch tube to length for a 60 PSI shot, the trace shows acceleration the entire length of the launch tube with a noticeable drop in acceleration along the length. The exit point is now at the peak speed. Taking the time to cross the last two coils shows a speed of 454 FPS. A field test shot produced a launch of over 300 feet with a foam ball.
    Here is a video of the 4 inch foam ball launch at Arlington.
    {4 inch foam.avi}

    As a pleasant surprise, the optimum length was not 4 feet, but 5-1/2 feet. The trace also shows that after the first coil is crossed, the acceleration is already starting to drop, which is good. It shows the valve is not still opening. After the first crossing, it is wide open. Using a french curve and using the peaks of the traces, the expected zero speed point can be found. The first coil is detecting a voltage at this time, indicating the valve is in motion. The starting time of the motion prior to the acceleration curve crossing zero, shows the valve opening time. It looks to be under 1 ms. This is the ideal launch tube length for this pressure, valve, tank, and load. Muzzle exit is at peak speed.
    {web_60_PSI_Foam_ball.jpg} 60 PSI foam ball launch from 4 inch tube after trimming. There is almost no speed increase in the last foot
    (view changes)
    10:10 am
  2. file 4 inch foam.avi uploaded
    10:10 am

Monday, December 22

  1. page The brag zone edited ... Here is the landing of a Gateraid bottle next to the 50 yard line. It was launched from the sh…
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    Here is the landing of a Gateraid bottle next to the 50 yard line. It was launched from the shop out near the street on the far side of the school from the track. If it was launched from the outside edge of the track behind the goalpost behind me, it would have landed way up the hill behind the scoreboard and tennis courts.
    {Gateraid.JPG} Gateraid Landing
    Here is a video of the Gateraid launch. I should have taken my keys out of my pocket. The hard recoil gave me a bruise where my keys got squished into my leg. Note the recoil. Even though I braced for the launch, I still needed to take a step to keep balance. Video by Mr C.
    {3 inch Gateraid shot.avi}

    Pop cans don't survive the landing, even on grass.
    {Popcan.jpg} Pop can burst on landing
    (view changes)
    4:58 pm

Sunday, December 21

  1. page Blazer Game edited ... {PC120030a.JPG} 4th Quarter timeout chaos Arlington team photos by Technician Great video o…
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    {PC120030a.JPG} 4th Quarter timeout chaos
    Arlington team photos by Technician
    Great video of the launcher at practice. Crank up the sound. A quick dump valve is impressive.
    {t-shirt_blazergame-practicevideo.avi}

    The team effort was covered by the East Oregonian newspaper by reporter Erin Mills.
    http://www.eastoregonian.com/main.asp?SectionID=13&SubSectionID=48&ArticleID=86533
    (view changes)
    7:25 am

Thursday, December 18

  1. page The brag zone edited ... To get things started, here is a photo series of how a technician makes a valve core without a…
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    To get things started, here is a photo series of how a technician makes a valve core without a lathe or round stock. To make a fast valve, we wanted to create a valve that was fast, has a short flow path, large opening, and reliable.
    We chose these goals to beat average designs and their limitations. Sprinkler valves are fast, but have flow problems as they have limited sizes, complex flow paths, and many tend to re-close early as the surge supply is depleted faster than the trigger bleed. For this reason, many of them make great air horns unless modified. Ball valves while having a short straight through flow when open, it's opening time is limited by the ability of an operator to get it open without the partly open valve severely limiting the energy transfer to the shirt. Our final design is taken from a piston valve design that was modified to meet the speed and flow design needs while eliminating many of the pitfalls of piston, sprinkler, and ball valves.
    ...
    and length foof the piston
    An air operated version of this style valve is often referred to as a quick dump valve. They are often used to quickly dump chemical tanks. They are seldom used for air as commercial quick exhaust valves are used instead. Building a reliable quick exhaust valve without a machine shop for the tight tolerances needed is very difficult. The quick dump valve did not need any special high precision machining, springs, or other hard to manufacture parts. The o-rings that fit the pipe were located at a local hardware store as a replacement part for a kitchen faucet. They were 60 cents each. The valve core was turned to fit these o-rings.
    The initial opening speed was considered to get the opening avalanche started faster. It was decided to decouple the trigger rod from the valve core to reduce moving mass further and permit an impact to start the core motion. This operation is much like a cue stick hitting a billiard ball for a short acceleration time. The last item to increase opening speed was the selection of the material. Light and strong is desirable. The ability to work with it was a must.
    (view changes)
    1:43 pm
  2. page The brag zone edited ... Now that the submissions are all in for judging, it's time to share a little. To get things s…
    ...
    Now that the submissions are all in for judging, it's time to share a little.
    To get things started, here is a photo series of how a technician makes a valve core without a lathe or round stock. To make a fast valve, we wanted to create a valve that was fast, has a short flow path, large opening, and reliable.
    ...
    their limitations. Piston valves work well but present construction problems and they tend to have a limited operating range in addition to getting the valve properly seated closed. Many which are not designed to be quick exhaust valves can operate quite slow unless the pilot is also very fast. Many home built piston valves tend to break at high pressure from the g forces they are subjected to. Sprinkler valves
    Most piston valves are opened by releasing the air pressure holding them closed which brings up the first problem many piston valve builders face. It is very difficult to get an initial seal in order to build pressure. The second problem is the mass of the valve piston. They are often long and large in diameter. The third problem is often related to the slow rate the trigger pressure bleeds off while the tank pressure dumps, causing an early re-close limiting the launch power. To solve all three problems, a solution was considered. To reduce the diameter and length fo the piston to reduce the mass of the moving piston a small diameter is used. The use of o-rings is used to eliminate a large difficult to seal flat orifice seal and permit using a piston much shorter than many piston valves. A manual trigger for a reliable open and close is used while retaining the speed of an air opened piston valve.
    An air operated version of this style valve is often referred to as a quick dump valve. They are often used to quickly dump chemical tanks. They are seldom used for air as commercial quick exhaust valves are used instead. Building a reliable quick exhaust valve without a machine shop for the tight tolerances needed is very difficult. The quick dump valve did not need any special high precision machining, springs, or other hard to manufacture parts. The o-rings that fit the pipe were located at a local hardware store as a replacement part for a kitchen faucet. They were 60 cents each. The valve core was turned to fit these o-rings.
    (view changes)
    1:42 pm
  3. page The brag zone edited ... Now that the submissions are all in for judging, it's time to share a little. To get things s…
    ...
    Now that the submissions are all in for judging, it's time to share a little.
    To get things started, here is a photo series of how a technician makes a valve core without a lathe or round stock. To make a fast valve, we wanted to create a valve that was fast, has a short flow path, large opening, and reliable.
    ...
    fast. Many home built piston valves tend to
    Most piston valves are opened by releasing the air pressure holding them closed which brings up the first problem many piston valve builders face. It is very difficult to get an initial seal in order to build pressure. The second problem is the mass of the valve piston. They are often long and large in diameter. The third problem is often related to the slow rate the trigger pressure bleeds off while the tank pressure dumps, causing an early re-close limiting the launch power. To solve all three problems, a solution was considered. To reduce the diameter and length fo the piston to reduce the mass of the moving piston a small diameter is used. The use of o-rings is used to eliminate a large difficult to seal flat orifice seal and permit using a piston much shorter than many piston valves. A manual trigger for a reliable open and close is used while retaining the speed of an air opened piston valve.
    An air operated version of this style valve is often referred to as a quick dump valve. They are often used to quickly dump chemical tanks. They are seldom used for air as commercial quick exhaust valves are used instead. Building a reliable quick exhaust valve without a machine shop for the tight tolerances needed is very difficult. The quick dump valve did not need any special high precision machining, springs, or other hard to manufacture parts. The o-rings that fit the pipe were located at a local hardware store as a replacement part for a kitchen faucet. They were 60 cents each. The valve core was turned to fit these o-rings.
    (view changes)
    1:40 pm

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