DIY PVC Crossbow (Pt. 1/2)
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DIY PVC Crossbow (Pt. 1/2)

August 14, 2019


Hey guys welcome back Thanks for joining us today on the king of random. The crossbow is a weapon and tool that dates back Thousands of years and has been used for hunting and warfare. It has great range a lot of power and often takes less training to learn to use wealth and other types of bows. The purpose of today’s video is to learn how we can build our own crossbow using a 2×4 some PVC and some paracord We also have a couple of wooden dowels and a small piece of 3/4 inch plywood. In this video, We’ll be using two by four PVC and paracord to build the body and bow of our crossbow. In our next video, we’ll cover how to build the trigger mechanism and the arrows. Let’s get started as a first step Let’s measure 2 feet from our 2×4 and cut it off with the chop saw. Well. I’ve got my chops I’ll I’m also gonna cut off two pieces of my 3/4 inch schedule 40 PVC One piece will be 30 inches long and one piece will be about 1 foot long With these pieces cut there are some more details that I need to add to the body of our crossbow, so it’s not just a block of 2×4. I’m going to draw those out with a sharpie and then cut them out with a bandsaw This is going to be the front of the crossbow and this will be the back. This notch up the front is where our bow will sit Resting against the body of the crossbow. This piece that I’m removing is to create a handhold right here Where it can hold on to the front of the crossbow this larger piece is being removed for two purposes. First it makes the crossbow a lot lighter. Second, we’ll have our trigger mechanism on this part of the crossbow There we go. We’ve got the basic shape of the body of the crossbow. Now, I’m going to use the belt sander really quick and take down a lot of the sharp edges and plane out the top of it so it’s a little bit flatter and smoother. The body of the crossbow is cut out. It’s sanded, it’s smooth, and comfortable to hold now. Let’s move on to making the bows Clearly to start out with our PVC pipe is round and we want it flat so what we’re gonna do is we’re gonna take our heat gun we’re gonna heat up the pipe And then we’re gonna smash it flat using our vise Now the clamps of the vise are not as tall as the PVC pipe and it has this knurled texture Which helps you get a lot better grip But we don’t want that texture smashing into our PVC so what I’ve done is I’ve thrown together a couple of blocks Using two by four and just glued a couple of scraps of wood onto the top these fit nicely in the vise and I can fit the PVC pipe between them and smash it there That gives me a much larger surface area And it’s a lot smoother than the gripping services of the vise. Now with our heat gun, we want to heat up the PVC pipe four or five inches of length at once we want to make sure we keep the heat gun moving and the pipe rotating so that we don’t burn it in any one spot With your PVC heated up we want to sandwich it between the two blocks. I’m just going to smash this down until I can’t really smash it any farther. Now the PVC is somewhat elastic so if we were to unclamp it right now We can see that it will start springing back to its shape and that’s not what we want We want it to stay flattened the whole time so what we need to do is leave it clamped as it cools down if it cools down while it’s in the clamps It will hold its flattened shape while this portion is cooling down. We’re going to warm up the next four or five inches As you heat up the next length of the PVC be sure you support it at the back so that it doesn’t sag down When the PVC is warm it could even tear if you let it sag too much All right Got some good squishiness flexibility. Let’s loosen our clamps I’m just gonna kind of push it through you can see it’s kind of getting squished on its way through and I’m not going to Push it all the way through so that the already flattened portion is completely out of the clamp I want to sort of use that to make sure I don’t end up twisting as I go If I use this as a guide it will all stay flat in the same plane It starts taking longer the farther down you go because the wood blocks themselves Get pretty hot and PVC really needs to cool down while it’s sandwiched in between them Which is harder for it to do when the wood itself is not cool you can see here that I got a little bit of a bend in the bow and I want to take that out because I want it to be a little straighter, so I’m gonna try reheating this portion just Bending this end part down a little bit. We’ll see how this goes It is letting it Bend now, although it’s also Puffing back up kind of taking on more of its tube shape again, which is not really what I wanted I’m gonna help it stay flat. I’m just gonna sandwich it between a couple boards here. It’s a waiting game now There we go we’ve got The first piece of flattened PVC which will turn into the main bow on our crossbow? Now let’s do the same thing to our one foot piece While our smaller bow is cooling down in the clamp We’re gonna work on shaping the main bow for our crossbow The first step is we’re going to try and heat up this piece of flattened PVC About 2/3 of the whole bow here in the middle. We’ll leave the ends cool the way they are for now Similar to when we tried to adjust the curve in the bow before it’s likely that some parts of the PVC will start to split apart and Lose the flattened shape that we’ve given it as we add the curve. Hopefully the pressure of bending it will flatten it back out So you know we’re doing I’m gonna try and add just a gentle curve into the whole bow Don’t want it to be too extreme. We don’t need any sharp angles or anything And I’ll give this a few minutes to cool off and hold its shape Now we have a nice curve in the PVC which is going to become our primary bow but to give it a little more strength We’re going to try and add a little bit of recurve on either end this will make it so as the bow is pulled down It not only has to bend on one side, but it has to straighten out the edges this will give us a lot more power That feels fairly flexible You can see it started to sort of balloon out. I think as I wrap it around the fire extinguisher It will just smoosh it back down pretty well Down enough to hold its shape do the same thing on the other side All right there we have it there’s our primary bow It’s a good curve in the main body of it, and then some recurve on the ends This second piece of PVC is actually going to be a second bow that goes on our cross foot This piece of PVC with its curved and recurved ends will give us a fair amount of force but it is still PVC and traditional crossbows would use either a laminated wooden bow or a metal boat to give it extra strength Since PVC isn’t as strong as either of those there’s going to be a secondary bow on top of the first one curving in the opposite direction a Second string will connect from one End of the large bow over the smaller bow and then back down to the other side So the same way we did with our large bow we’re now going to heat this up and add a gentle curve to it All right Add a slight curve into this Some of you may recognize our original backyard foundry. I’m just gonna use this as a curved surface to wrap this bow around Here we go we’ve now got our two separate bows And we need to attach these to the top of our crossbow in order to find out the exact center of the bow I’m gonna Put it on this stick and try and get it to point where it’s perfectly balanced. It’ll mark that point Let’s take our larger bow and line it up on our two-by-four body And we’re gonna want to pre-drill a couple of holes that go through the bow and into the wooden body The large bow will go right here where we’ve just drilled it out The small bow will face the other way so they curve in opposite directions With these two bows set up the way that we want them we’re going to drill through the holes that we already put in our Larger bow and down through the smaller bow to make sure the holes all line up exactly where we want them With our screws driven just slightly through the two bows we can now align the two screws with our Pre-drilled holes on the body of the crossbow Those fit pretty well, let’s temporarily remove the screws in the bows and then make our modifications before we reattach them On the larger bow we need to add notches to allow for the connection of our bowstring For decorative purposes, I’m also going to cut off the very edges of the bow at an angle There we have it that should work great Our smaller boat doesn’t need to be cut in the same way to hold the drawstring But we are going to sand some grooves into both sides So that as a drawstring passes over it it will stay centered the way, it’s supposed to With the modifications complete on both bows let’s reattach it onto the body of the crossbow The bows are complete they’re added to the body, let’s try adding some bowstring here. I’ve got some paracord I’m going to tie a loop in one end measure out the correct length and then tie a loop in the other end you need to be sure that the loop and your knot is large enough that it can fit over the knots you’ve cut into your bow Now we also want to make sure that when our bow is strung There’s already a little bit of tension on the bow So I’m going to pull slightly on the bowstring if you can see that the bow starts to give a little bit That’s the length we want the paracord to be where we add the other loop Cut myself off plenty of extra here if you keep your knot nice and loose you can easily adjust it as you measure That looks like pretty good spot make sure that I’ve got enough loop fit around the notches There we go it’s under a little bit of tension we can see it if I draw it back It Springs forward, so I think that is a good length of bowstring right there now I’m just gonna cut off the excess here, and then I’ll fuse the end of the paracord using a lighter Now like I said this has some spring to it But not as much as we want so we’re going to add another string that goes from this end of the bow Up on top of the second bow and then connects again to the notch on the other side Take our paracord make sure our end is sealed off Start with another bowline knot slip that over the notch on one side And you measure going across the top down to the other side Now I haven’t tied it off yet, but if I just wrap it around a couple times You can already see that now when I pull on it this cord going along the top is forcing the second bow to flatten out which adds a lot more tension into our crossbow now we want to tie another loop in the end of this piece of Paracord so that it’s quite snug as it wraps around this knot To make it a little bit easier to attach the second string you can put it on the notch Without it being over the bow and then stretch it over one side at a time There you have it that’s how you can build your very own crossbow using a Two-by-four for the body some PVC piping for the bow and some paracord for the strings like I said in our next video We’ll go over how to build the trigger mechanisms and the arrows that used thanks for joining us for this video And we look forward to teaching you how to finish your crossbow in the next one talk to you then That is toasty holding on to that little part in between the blocks. I’m sure it’s still very one

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  1. Mate u need to wear a respirator when heating pvc as it can release a deadly chemical if it were to burn

  2. Should’ve left the main shaft straight and had just the recurve would’ve provided more flex and poundage. Still neat tho

  3. the front notch where the bow sits should be in the middle of the stock, not on top, so it sits neatly between the wood for added stability. also, the notch should be at a slight 5-10 degree angle upwards so that the bow and the string sits more evenly on the deck instead of bending/pinching down in the middle. sorry if unclear english. screws.. work for plastic, I guess. Traditional crossbows are clamped to the stock. Clever idea with the second counterbow.

  4. It would work a lot better if you put fiberglass inside the pvc and do not pre-bend the bow. Re-curved tips are okay. A fast flight string would make a big difference too. Para cord stretches way too much.

  5. Me dejaste con las ganas de ver una prueba de funcionalidad.. quería ver disparar una flecha..pero bien!👍👏👏👏👏

  6. If you made the wood blocks that you put in the clamps longer….. Might be better in this application….?

  7. A busy dude. I really enjoy King. Such an intelligent mechanical mind. 95% of his content is concise and relevant to the task at hand. Thank-you.

  8. I think I'd make a second set of those "smooth wooden 2X4 vise jaw inserts" so that one can cool while the other is being used.

  9. I had never before heard of a "hear gun". I saw it in action and all I could think of was "That's just the meanes hair dryer".

  10. i would put the pvc in an oven for 30 seconds on low heat and then squish the whole thing at once in between 2 2×4's!

  11. Dude get a wet shop towel and use it to quick cool the PVC as well as the wood blocks or if you can in you shop pour water on both to quick cool.

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