Introduction: PVC Bows
Hello and welcome.
Today we will go over how to make a flattened PVC bow.
Flattened PVC bows are an amazing way to get into archery or bow making for a fraction of the cost of just buying a bow or making your own self bows. Because PVC is so cheap and widely available there is basically no cost of entry, and for only a few dollars you can make your own functioning bow for target practice, hunting, or just for the enjoyment of making your own bow. PVC bows also have the added benefit of being quick to make. Requiring very little time in the tillering process to get a nice even curve, PVC bows naturally work very efficiently and can provide a lot of entertainment for just a few dollars while also providing a nice fast bow for the learner or the certifiably skilled archer.
One 5ft section of SCH 40 3/4" PVC pipe (SCH 80 or 1" diameter pipe can be used if you want a higher end draw weight.)
One heat gun (or other heat source, but a heat gun is recommended.)
Two 2x4's at least as long as half of the length of your desired bow.
Something to cut down the ends, I use a rotary tool, but anything can be used from hacksaws to files.
Some time, the time spent making the bow will almost always correlate to the quality of the finished bow.
A bow string 4" shorter than the finished bow, I recommend starting with para-cord as it is cheap and allows you to retie along the way until both the para-cord and the bow stop their initial flex and set in phase, at which point you can then buy the materials to make your own bowstring, or buy one that is the right length for your bow.
Aluminum Foil is recommended to aid with heating to help with even heat distribution.
IF you want to make a recurve you will also need something round to make the recurve with, I recomend a small pot, and something to hold the limb tip to the pot, I use a C-clamp here.
Step 1: Deciding What Type of Bow You Want
In this section we will cover types of flattened PVC pipe bows.
Arguably the hardest and the most important part of making a flattened PVC bow is to decide what kind of bow you want. The possibilities are endless, but the three main kinds of Flattened PVC bows are Longbows, Recurves, and Horsebows. Longbows are very straightforward and require the least amount of work but will translate to slower arrow speeds and more hand shock in the finished product. Recurves are the next step up difficulty wise and will balance speed and comfortability. And Horsebows are specialized recurves which use non-moving 'bow-ears' called Siyahs. My personal favorite to make are normal recurves as you can get very fast bows with not a whole lot of effort. Do keep in mind that you are building a weapon and you should take every precaution while using it to ensure your own safety and the safety of those around you.
Step 2: So You've Picked Your Style of Bow
Now that you've picked your style of bow its important to decide what you want out of your finished bow.
Maybe you just want something for target practice, maybe you just want something that looks cool for cosplay or larping, or maybe you want something for hunting.
It's important to decide what you want from the bow because this is the point where your decisions will impact the draw weight of the bow the greatest.
Shorter bows will have a larger draw weight without adding mass to the limbs, but will experience something that archers and bowyers call "stacking." Stacking is what happens when a draw-length exceeds the "optimal draw" of the bow. It is an exponential increase in draw-weight while everything up to the 'wall' is linear. Stacking is not very comfortable, but the higher draw-weight and smaller limbs do lend themselves well to faster arrow speeds. Shorter bows are also easier to maneuver around trees.
Longer bows will require more material to flex to achieve the same draw-weight as shorter bows, and because of that longer bows will tend to be less efficient than shorter bows, but they will be far more comfortable to shoot because you wont experience stacking or near as much hand-shock.
One final thing to consider is string pinch. Your fingers will have to go on the bowstring at full draw unless you use some sort of release aid. Shorter bows will have more finger pinch than longer bows will because at full draw the bow string has a higher angle of attack. Again it's a trade-off of efficiency for comfort.
If you are only going to use this bow for target practice or learning. I recommend starting with a full 5ft (or longer) section of 3/4" SCH 40 PVC pipe, in the electrical conduit form which will end up yielding a lower draw-weight that for a beginner is more fun to shoot with and will allow you to grow into a stronger bow.
If you are using this bow to hunt with, it must pull at least 30# in most states. To achieve this figure you will want to use 5ft of 1" SCH 40 PVC pressure rated plumbing pipe, or 4ft of 3/4" SCH 40 PVC pressure rated plumbing pipe.
If you want to chase the absolute highest draw-weight. I recommend 4ft of 1" SCH 80 plumbing PVC. You can even experiment with adding Siyah's to lower your effective limb, increase stacking and therefore increase your draw-weight while also decreasing the mass at the end of your limbs leading to a more efficient and 'quicker' bow.
Step 3: Gather Your Items and Set Up.
PVC heats up fairly quickly, but it also cools down very quickly. In this set up you will be heating up the pipe along key sections and quickly moving it over to the two 2x4's where you will then press and flatten the limbs, and press the handle. Having your heating set up close to the 2x4's is critical, I recommend using the 2x4's to hold a sheet of aluminum foil to help radiate the heat back at the pipe, which also means that the boards are available right away for pressing the limbs.
Keep in mind that heating PVC can be dangerous. PVC is Polyvinyl Chloride and is ~56% chlorine by weight. If you burn it it will put off Chlorine gas, which can burn your lungs and skin and can be very dangerous. Please heat the PVC in a well ventilated area and take extra care not to focus the heat on any one spot for too long. Simply heating the PVC to the point where it is malleable will not release chlorine gas, but burning it to the point where it discolors and becomes brown or black will. If you do happen to burn a spot or two the amount of chlorine gas should not be enough to hurt you, but I would not recommend inhaling the fumes from the burn. Also be aware that heating the PVC to the point where it is malleable means you will be getting this PVC very hot. Take care to not burn yourself, and I would recommend gloves to help avoid burning your hands, but they aren't required.
So once you have your tools ready to go, and your heating setup ready its time to start making the bow. In this guide I will show you how to create a Recurve PVC flattened pipe bow using 3/4" PVC plumbing pipe. To make a longbow, simply follow these steps without the recurve. To make a horsebow, shorten the length make some siyahs, and pop those bad boys in.
Step 4: Measure Cut and Mark
Measure your PVC pipe out to the length you want it and cut it down. Here I chose 4ft.
Then mark the center of the pipe, for me that is 2 ft from either end. Make two marks 2 inches on either side of the center mark and rotate the pipe to draw a circle the entire way around the pipe. This middle section will be your handle. Try holding the pipe on that section out at arms length and note how you feel about the length. Make sure that your hand can hold the pipe within the 4 in middle section. If you are comfortable with the length and handle section proceed to the next step.
Step 5: Heat a Limb
Using the heat-gun, heat from the outer line to the end of your pipe taking care to move the heat-gun slowly and evenly down the length. Note that if you were to only pass the length of the limb the pauses at the end of the pass will cause your hand to hover over the end of the swing for longer than at other points during the pass. Because of this you should "work your way in, and work your way out" by slowly shortening the distance your hand travels little by little until you are just in the center of the limb, and then working back out to the tips. It could be helpful to imagine a game of pong where the paddles slowly get closer and closer, and then further and further from each other and the heat-gun is the ball. Once the limb is pliable move on to step 6.
Step 6: Press the Limb
Now that the limb is hot and malleable, line it up on your 2x4 taking care to keep it as straight as possible, and squish it between the boards. Try to get the tip of the PVC out close to the end of the bottom board the press can fully flatten the limb at the tip. Put your weight on the limb and once it cools enough that the limb isn't malleable anymore you can get off of it and survey your work. If your limb is twisted, or not straight reheat it and try again, the good part about PVC is that you can reheat and repress the PVC as much as you need and it wont lose much strength at all.
Once you have a good press on the first limb, return to step 5 for the other side of the bow, and when you go to press the new limb, make sure that the straight part of the first limb is touching the bottom 2x4 when you press the second limb. This should make it easier to ensure that the new limb does not twist in relation to the first limb.
Step 7: Squish the Handle.
Just like you did with the bow limbs, but now in the opposite direction, we are gonna squish the handle to make it not bend with the rest of the pipe. DO NOT FLATTEN THE HANDLE.
This step we are just deforming the pipe enough to make it not want to bend where your hand goes. If you fully flatten it, the bow will collapse to the side when it is strung and your time will have been wasted, Read: the bow will not work.
Just lightly press the handle so it wont bend, I also like to add a little reflex here, which is just bringing the tips of the bow forward this will help make the bow have a higher draw-weight and transfer less energy to your hand. We will be adjusting the entire reflex/deflex of the bow in step 10, but this here will be more of a gradual curve through the handle.
Step 8: Adding a Recurve.
Skip this part for a longbow.
This is my favorite part.
Find a pot about the radius that you want your recurve to be.
Clamp or otherwise affix the end of the bow limb to the outside of the pot.
Heat the end of the bowlimb through to the point where you want the recurve to end, I like bringing it around until it is facing forward, but less or more could work with about the same efficiency.
Pull on the pipe to bring the limb end to the profile of the pot, and have it gently transition back into the limb of the bow.
Hold it like that till it cools and repeat for the other side.
Step 9: Flatten Then Cut the Tips.
Here we are gonna re-flatten, cut, and shape the tips of the bow.
Reheat the last inch of the tip and squish it entirely flat.
Draw a rough shape for the tip and cut it down to size, and add in cutouts on either side of the tip for the string.
Repeat for the other side.
Step 10: Reflex/Deflex
Congratulations, you've made it to the last step before stringing.
Sadly, this is the hardest part, but don't get discouraged you can do it.
Quick terminology here, Reflex is when the limbs of the bow come forward to the "back" of the bow (the part that faces away from the shooter.) Deflex is when the limbs of the bow come backwards to the "belly" of the bow (the part of the bow limbs that face towards the shooter.)
The more reflex your bow has, the heavier the draw weight and the faster the arrow speed.
The more deflex your bow has, the lighter the draw weight and the slower the arrow speed.
If your recurve only has reflex, chances are you will not be able to string it. Every recurve bow needs some reflex, and some deflex to be an effective bow.
Heat the first inch of the bow limbs next to your handle until it is pliable, add Deflex to the bow until it is just about flat across or has a little bit of overall deflex down the majority of the limbs before the recurve tips.
This is the step where you can fix any twist your bow might have developed make sure to get as much of the twist out of the bow as you can before proceeding, and allow the bow to cool fully.
Step 11: The Final Step I Promise.
Take your para-cord, and tie a small loop, this will be the bottom loop of your bowstring.
Put the string into place on the bottom limb of the bow.
Pulling the string up the bow measure to about 4 or 5 inches under the other end of the bow, on this side tie a bigger loop that can pass the limb through it.
Take the string off of the bottom limb, pass the top limb through the big loop, and put the small loop back into the slots on the bottom limb.
By bracing the limb on your leg, step through the opening between the limb and the bowstring.
Pull the top limb with your arm, push the bottom limb with your leg (being careful not to allow the bow to twist) and seat the big loop into the cutouts on the top tip, or if you happen to have a younger brother who wants to push the para-cord into place you can allow him to do so.
Congratulations, you have just strung the bow for the first time.
Next measure the brace height, the distance between the back of the handle and the bowstring.
I ended up getting a first brace height of about 8 inches, which is acceptable but not ideal for me. So I adjusted the length of the bowstring down and got a brace height of about 6 inches, which is a little bit short, but acceptable in my opinion. Keep in mind that most modern recurves will have a brace height between about 7-9.5 inches, and the smaller the brace height the more willing that bow is to punish your wrist should you make a mistake while shooting but the more efficient the bow will be as it has that extra inch or two to accelerate the arrow.
Hopefully you enjoyed my instructable, it is by no means a full and detailed breakdown of flattened PVC bows, but ideally it will give you a quick understanding of these amazing bows and how to make them. Also note that I am by no means an expert, and there is always room for improvement. Here you can see that my bottom limb has more deflex than the top and this came through with a bigger bend. I will be going back through and fixing that evening them out a bit more and having them pull more smoothly with eachother. If you end up having a little bit of a difference and you don't want to fix it, make that limb your upper limb. The string travels a slightly smaller distance because of the offset of the arrow nock from center to be able to shoot off of your hand, and by making the top limb the weaker limb you lessen the impact that it will have on the flight of your arrow. Thank you for the read and have fun with your bow!