i made a system for photographing projectile impacts safely (safe enough) and i thought i would share it with you all
i was originally going to hold off until im finished but with funding problems ill post what i have done now
first is the timing unit ... i chose to use the ever so popular camera axe as its a proven system
i originally purchased the projectile sensor that they sell with the camera axe but i broke it so i made my own
my original plan was to use 2 opamps 2 IR LEDs 2 IR phototransistors and 2 pots but after some playing around and looking at the source code that was ll not really necessary ... i settled just on 2 IR phototransistors, 2 IR LEDs and 4 resistors (i did not have a 500ohm resistor so i used 2 1Ks making the resistor count 4)
the air canon i made wayyy back when i was 15 but i remember it like it was yesterday!
i used a 5 gallon propane tank as the main tank and i pump it with a 2 gallon 150 PSI compressor and send it threw a 3/4" solenoid valve and in to an L joint than i can either put my .75 cal barrel on or bring it down to 1/2 inch for my .50 cal barrel
the safety box (i dont know what else to call it) is made of 1.5" wood reinforced with metal and long 2.5" screws
the glass on the front is 1/4" polycarbonate that is rated for 22 caliber bullet impacts (according to the guy who sold it to me) i bent it my self with a torch (it took FOREVER) and i mount it with bolts and washers
i dont wanna upload a ton of images so i put the canon and the box in one collage
the vents on top prevent the blow out of the screen after 150 PSI have been dumped inside and can force out a great amount of air (for more than can be forced in) while still protecting everyone from flying glass and debris
the spring in the back is very stiff and mainly just help disperse energy and putting more metal between the cardboard and the back to prevent anything from going wrong
the cardboard now consists of a combination of cardboard and foam rubber to help my sharper projectile slow down and i made a small cardbaord box filled with scrap flexible plastic and cardboard to slow it down better (it works)
my primary projectile is this
its made using a half inch welding steel bar and is about 3" long cut using a grinding wheel and a bench press and shined using progressively finer sandpaper
the ridges are on there to reduce rear weight, help break whatever it hits more and help it stop but in the end it just looks freaking cool
i also use wooden slugs and gluesticks
the camera is a nikon D7000 and the flash is an SB-600 for now
i trigger the flash in a dark room at a high camera ISO and a low flash setting to capture the motion quickly
is this hole thing an overkill? ... yes ... was it fun? hell yes XD
so whats left undone?
my highspeed flash unit
but im on my way to finishing it
i need to get some glass for the flash tube and i need a 40kv pulse transformer to trigger it
so far total project cost is $350 ish (not including camera or flash im a photographer i had that already)
so far only $50 for the flash unit
yes i know my english sucks i dont need your feedback on spelling or grammar issues
project was inspired by a HaD posting (the one with the spark flash)
the fastest thing i clocked on it was a gluestick at 918FPS ... thats over 625 miles an hour!
what do you guys think?
EDIT: VIDEO of the canon in action http://www.youtube.com/watch?v=YYs0WZBRtLA