now i made a lot of slices back and forth you don't need to do that one or two is enough but i wanted you to be able to hear it the next step i don't understand why this works but it really does in order to get this to split effectively you want to wet that scratch it works don't know why but it does then you want to turn the scratch away from your body so it's facing away from you and then you want to place your thumbs see if i can find this yes place your thumbs directly behind the scratch so that you push against where the the scratch is located and then just give it a snap like that it's that easy now if you're scared of getting your fingers near the cut do not put your hands way back here thinking you're going to protect them you'll probably shatter the tube in about five or six places and actually have a much greater uh likelihood of cutting yourself if you're really scared the first couple of times you do this put on a pair of gloves just make sure that you approximate your thumbs when you do that snap it's really easy and you get a really good cut it works very well now the next thing that you have to do is you're going to have to close up the end of the tube if you look at this finish tube here you'll see that what we've made is what looks like a very tall test tube out of this end of the tube and in order to close that off you could in theory heat this up with the torch and just use either a piece of graphite like this which is an unfinished rocket nozzle or a piece of wet wood or anything else and as you get it hot you could kind of try to work it in to close off the end of the tube it's a lousy way to do it because what will happen is you'll often distort the end of the tube maybe even mushroom it out a little bit and when we mount this we want a very close fit with the inside diameter of the hole so we get good heat transfer from the heat source so the better way to close this off is to actually draw the end down what you do is you put this in the flame like this and you're going to literally draw the ends closed the problem with doing it just like that is that in order to not burn my hands i have to work pretty far up from the end here and so what we're going to do when i get this thing started up i'm going to turn on the fuel is we're going to use a little technique that will save a lot of glass let me just get the tanks going turn the oxygen on and off only after the fuel has been turned on so we start by turning on the fuel and now we add the oxygen and when you want to turn the oxygen off you turn it off first otherwise you get a really loud pop it's kind of scary so let's get a little oxygen going here
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