How To Make a Compound Bow With Let-off - Part 2

Hey guys and welcome back to part two of the tutorial on how to make a compound bow. If you haven't already seen part one of the tutorial or the shooting video, I'd strongly advise it before you make the bow and there'll be a link in the description down below. So this is where we left off after part one and we've got the cams and the riser completely finished so let's move on to making the limbs. I'm going to be making the limbs out of some fiberglass tent poles and these fiberglass tent poles are pretty bendy and very strong. You can buy fiberglass tent poles off ebay or off amazon and you can also scavenge them from old tents. As you can see all four of these fiberglass tent poles have the metal ends on and they're going to be quite important later on. So the first thing that I'm going to do is take a metal hacksaw with a metal blade and then I'm going to chop off half of the metal bit on the end of each of the four fiberglass tent poles. Once that's done I then chop the total length of all four of the fiberglass tent poles down to 40 centimetres long, that's approximately 15 and a half inches. Then using some of the excess from each of the tent poles I've got a smaller piece of tent pole in between both of the longer ones which is 25 centimetres long. It's important to have this so the bow will bend evenly. I've now wrapped a piece of grey duct tape around the very end of the bow limbs and this is going to be the start of putting them all together. I take a thin piece of 18 millimetre pine wood and file two grooves in the end of it using a rat tail file. Once I've done this, this holds the limbs far enough apart so that the cams can easily fit on the end. I then drill a hole in it so that it can sit over the middle piece. Once that's done I then tightly wrap the rest of the three pieces of fiberglass limbs with duct tape. I've made sure that when I wrap it the piece of wood holds the two end fiberglass limbs far enough apart so that cams can fit in between the gap. Then using some very thin kite cord I've painstakingly wrapped the whole of the limbs in some of the kite cord and this is going to act very strong to hold all of the limb together and as you can see I've also stopped quite far from the end so that it's not going to impact with the strings of the bow. I then duplicate this exactly onto the other one and I've got two fiberglass limbs which are very strong. You could alternatively make them out of schedule 40 or schedule 80 pvc pipe but since I don't have availability for that in the UK I'm just going to be using fiberglass. Once it's placed on the bow it looks something like this and I think it looks quite good so far. Now I'm going to show you how to attach them onto the oak bow. On this side I've attached them using lots of screws and a couple of bolts and secure very tightly so that the limbs will definitely not be breaking off. As you can see also over the attachment there's a piece of two millimeter plywood and that's just acting to distribute the forces over the whole of the limb attached to the bow so that it doesn't just squeeze one point. The first step in attaching the limb is to sandwich it between the piece of plywood and the oak bow and then I like to tighten it up with my g clamp and then I like to drill holes in and attach in some screws. I make sure that I countersink the screws deep into the plywood so that it doesn't have screws sticking out everywhere that would look very bad. I also add a couple of bolts and make sure to secure them very tightly. When I'm drilling the holes I'm trying to generally drill them in between the gaps of in between the pieces of fiberglass but I will sometimes occasionally hit a piece of fiberglass and if I tighten it up enough that won't really be a problem. It's really important that you do this step properly because if you don't do it properly when you pull back the bow the limbs could snap off and hit you. Once the limbs are attached I go to halfway down the metal piece on the very end of each limb and then I drill a 3.5 millimeter hole all the way through using my pillar drill press. This is going to act as a hole where the pins are going to go through and secure the cams. Once this is done I can use 3.5 millimeter pins which are actually just nails on the end of each limb and then that's going to hold the cams in place when I put them through the rotating hole on the cams and then this is going to be fine because the cams can rotate freely. I also drill another hole and just have half a nail sticking out and this is where the string is going to attach later on. Now it's time to make the parts for the cams which the string is going to attach onto so just drill through all of the holes which are on the blueprints and I again I use my drill press for this. Once that's done I can super glue some nails in and these are the same nails that I was using as pins earlier. I then need to cut them off and I'm just using a hacksaw with a metal cutting blade for that again and once I've cut them off it should look something like this. The bow is now finished and it's time to make the bowstring. This is probably one of the most complicated parts of the process and it's pretty hard to understand if you don't actually have a compound bow in front of you but once you've made your bow and you have it up to this stage you should probably be able to figure it out. I'm going to try and explain it as best I can but if you still don't understand either send me a personal message on YouTube, post a comment down below or just google it. So the first thing to do is select your bowstring. If you're having an incredibly low draw weight on your bow you could probably just use paracord but if you have stretching in a compound bowstring that's really really bad and the cams won't really work properly so I'm going to be making my bowstring out of some wire which is wrapped in some special cable stuff around it so that it's not sharp and it won't cut into me or the bow. One of the problems with wire is that it's pretty much impossible to tie into knots and it can become really frustrating when adjusting the length of the bowstring. So the very first step is to tie a bowline knot in the end of one of the pieces of wire. If you don't know how to do this just search it on the internet. Then cut it off at about 30 centimetres and tie another bowline knot. If it's too long just tie a normal overhand knot in it to shorten it a little bit. Then tie another bowline knot with a slightly wider loop in the end of a longer piece of rope. You then take the shorter piece of rope with two bowline knots in and then thread it through the wider bowline knot. This can then in turn attach around the two nails sticking out the end of the limbs. When pulled on like this it should pull evenly on either of the limbs. You now need to tie it off long enough so that it can attach around one of the nails on the shorter cam. You then need to do that on the other one as well and then you've got the two main bowstrings done and it's time to make the last bowstring. It is very important that both of these bowstrings are exactly the same length when pulled tight because if they aren't then one of the cams will reach let off before the other one and then the arrow won't fly properly. For the main bowstring you get a long piece of wire and tie a bowline knot in one end and then attach it around one of the cams and pull it over and round and then tie a bowline in the other end when it reaches the other cam. If you still don't understand how to make the bowstring and attach it then there's a link in the description down below to a tutorial. I like to fiddle about with the strings and make sure that they're all about the same length and then the tighter you make the two main strings and the bowstring the more draw weight the bow generally have. So now the bow is pretty much finished and all you need to do is attach it to an arrow and fire it. Unfortunately this is what happened when I tried it out for the first time. I then had to reinforce it and because of that there wasn't any room to make a proper arrow rest but when it was done it worked pretty well. I would really like to crank up the draw weight and make it much more powerful so that I have decent power but I would be worried that it would break again. So thanks for watching guys I hope that you've enjoyed this video and if you have then check out the shooting video of this bow and subscribe for more videos like this on other cool tutorials.