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Current time:0:00Total duration:10:27

Video transcript

okay so today we're going to show you how to make a projectile launcher this launcher was originally designed by Dave Bertrand's class in high tech high in San Diego he's an engineering teacher there and was a mentor of mine when I worked there so there are a number of different parts on this we're going to talk about each of them this is it's made out of three pieces of wood there's 2 1 foot square pieces that are three quarters of an inch thick those are three quarter inch oak veneer plywood we also have another piece here that's a five inch oak veneer plywood piece also three three-quarter inch thick and so let's talk about this first this piece has a bunch of different holes they're set at 10 degree increments along this arc and there's a 5/16 bolt that you can pull in and out and slide to change the angle of the launcher here there's another piece right here this is a piece of PVC it's 2 inch PVC it's screwed on to this extruded aluminum piece this is 3/4 inch extruded aluminum and it's connected with a 830 seconds by 1/2 by one and a half inch machine screw and then if you look over here we have a stop that's a 5/16 bolt and that that causes the the bar to stop so that the ping-pong ball is released we have a pivot point that's also a 5/16 bolt and those are 2 inch long bolts and the piece of aluminum here this is extruded 3/4 inch square tubular aluminum and it's 11 inches long and then we have a I screw here that's a 5/32 I screw that connects our spring the spring is a 830 sorry is a 15 30 seconds three inch spring and then we have a another 5/16 bolt a nut and we've countersunk a hole so the nut sits below the surface now let's take a look on the inside here we've also created some holes so we have a 5/8 inch center hole and a and a one-inch hole and the one-inch hole goes down about an eighth of an inch the 5/8 inch hole goes down about a half an inch and that allows the nuts and washers on the backside of these bolts to sit inside the bottom piece and for the two pieces of wood to sit flush which allows for like zero degree angle launches and things we also have two and a half inch hinges here in the back and so that's pretty much the launcher there well let's go ahead and get started so this is our launcher and it's the original design we've got the angle adjustment mechanism here you pull it back and you can launch it so that's basically how it works you can pull the pin out drop it down and have it flat so you're going to need a saw to cut the wood it's going to a circular saw will work great like this one a drill to put some holes in it you can also need a square a tri square like this works you can also use a rafter square and something to determine angles a compass a file is important you're also going to need a wrench and appliers hacksaw and some Spade bits and spiral drill bits so we've got our 3/4 inch piece of oak veneer plywood here and we've got all our parts laid out so our PVC and our different sorted washers and nuts and you can see that we also have our our different bolts and springs there as well and our piece of extruded aluminum and so we're going to go ahead and start making our first hole and that's going to be the hole for the 5/16 bolt that holds the spring in place that bolt right there and so the way we do this is we have two nuts on either side of the bolt that we tighten down against each other to hold the bolt in place and keep it nice and stable we're going to use in 7/8 inch spade bit and we've got it taped about a quarter of an inch up so we only go down a quarter of an inch and that allow us to countersink a hole and then we're using our 5/16 spiral bit so we can put our bolt in the wood and we're getting everything set up this is our pattern we drew on the computer and we're going to use that pattern to cut out different angles we're going to use a small three thirty-seconds bit to drill pilot holes which makes it easier to drill a larger holes with the 5/16 bit which is the the size of the bolt that will actually have there so the pilot holes help us to guide that larger bit into the correct location okay so now we're going to drill the center hole we're going use a 7/8 drill bit that's a spade bit we've got it taped a quarter of an inch up and that will allow a recess for both our top nut and our washer to sit in and then we'll use our 5/16 spiral bit to finish off the hole now we're going to drill our countersunk holes these are the holes that go in the bottom piece and allow the washer and nut and bolt protruding from the top through the bottom of the top to sit inside of the bottom board so we're just marking the center points for all of those different different bolts and we're going to use a one-inch spade bit and we'll go down about an eighth of an inch with that one H weight 1/8 inch spade bit we're taping that off about an eighth of an inch and then we're using a 5/8 inch spade bit to go down the rest of the way which is about a half of an inch and that'll leave enough space for the washer in the end of the bolt so there's the 5/8 inch spade bit going the rest the way and make sure you do the the smaller spade bit second now we're going to go ahead and set in our hinges they're measured about an inch in from the edge they're about two hat two and a half inch long hinges so we've lined everything up with the aluminum clamped it down lining the the hinges up and then we're just marking the center's and now we're going to take a sixteenth of an inch drill bit and tape it about 1/2 inch up and so we've got the holes and we're going to drill our put our screws in not going in all the way just yet but most of the way then we're going to mark the other side and put the holes in for that and now we're going to put our screws in on that side and then we'll go through and we'll tighten all of them down the rest of the way all right so now we're going to cut the angle portion the the part that has the arc of holes that allows us to set the different degrees of angle so we are just using our aluminum as a fence marking our part there this is the last cut we have to make on it it's 5 inches square so we'll take our circular saw and trim that off alright now we've got our piece we're just going to file that off very quickly to clean up the edges and then we're going to tape a pattern that we printed from the computer and use our 3/32 inch bit to create our spiral our pilot holes so we'll put our pilot holes in that and now we'll use our 5/16 inch bit to finish off the holes make them the full size all right so that's our the part that we just made we're getting it lined up and centered and we're going to mark it to line it up with our device and we're marking it so that we can put our screws in about 1/8 3/8 of an inch up from the very bottom of the device that means that the screws will be in the center of the bottom board we're screwing into we're using a sixteenth inch drill bit and we're spacing those holes about an inch and a quarter apart when you use some inch and a half long panhead wood screws to hold the to hold the angle piece in place so we're just drilling those holes and putting those wood screws in right now tightening it all down and then we'll check to make sure that it all fits right and moves and it does ok so now we're going to cut our our angle bar or launch your bar I should say and we're just using a hacksaw that's measured at 11 inches so it sits inside the edge from either side about a half an inch we're cleaning it up with a file there now we're going to mark our Center and drill our Center we're going to again going to use a 3/32 inch bit to create that pilot hole and then we'll take the bar down and we're going to line it up with the pieces that we want to bolt on to the bar and so we've got our PVC there and our eye screw for the spring so we're going to drill the holes for those two components all right so we're drilling our pilot holes in the aluminum bar that's going to launch the ping-pong ball and that's a 3/32 bit there now that we have our pilot holes we can put the larger holes in place for our eye screw and for the machine screw that's going to hold the PVC cradle in place now we're making our PVC cradle we're just going to cut it in half using a clamp and a hacksaw and in order to get it just right we need to sort of reposition it there now the hacksaw leaves a rough edge so we'll clean that edge up with a break-off blade knife you want to be careful doing that so you don't cut yourself and then we'll use a file to just smooth off the edges the rest of the way we'll mark the center about 3/8 of an inch up and drill a pilot hole and then our final hole now we're going to assemble all the different components we're inserting washers and then nuts on the top washers lock washers and nuts on the bottom for the bolt holding the spring in and now we're going to put our eye screw in and then we're going to insert the the center pivot screw and that's got two nylon washers and then two washers and two nuts and a lock washer on it so we can tighten that down that holds the bolt in place but still allows the aluminum to spin freely you can see there now we're going to put our stop in place and that's just a another 5/16 bolt with some nylon washers around it and we've got a PVC cradle that we've trimmed out there for our machine screw because it's got a flanged head and we're tightening that down now so we'll use our wrench to hold that in place and a screw driver to tighten that up so we've got our cradle ready to go so now we're going to take the spring and try and attach it using our needle nose pliers to the eye screw and then we're going to take our launcher and take it outside and do some tests we did a number of tests with it and we found that some of the time the ball would curve to the left and so we're going to make some design modifications in our next video