Monday, December 14, 2015

TUTORIAL: Make Your Own Bow Out Of PVC

Hi all. Sorry we've been away for so long, but 2015 was a crazy year! But today we're back with a new tutorial... How to make your own functional bow out of PVC pipe in the comfort of your own home! Nothing really specialised is needed. Just fairly regular tools!

There are plenty of tutorials around to do this, but unfortunately they're for the most part from America where they have access to a type of PVC called "Schedule 40". There's no real equivalent for wall thickness here in Australia where the Informed Preppers live, and so we've come up with a new tutorial to show you have to make bows out of PVC anyway, because why should we be left out of all the fun?

So here's what you'll need:

- A heat gun (though this can be done over a fire or any other decent heat source, you'll get more accuracy with a heat gun)
- A small and large round-backed file
- A heatproof glove of some kind (oven mitts work fine, but for better shaping, use something with fingers)
- A drill
- Gaff tape
- A tape measure
- A marker of some kind (I use a Sharpie)
- A decent saw with fine teeth (I use a tenoning saw and it does a great job)
- Paracord and a lighter for making the string (You'll get better results with an actual bowstring, but I'll go into that at the end of the article)
- A length of 20mm Class 12 PVC piping
- A length of 15mm Class 18 PVC piping
- A flattening jig (This is a custom-built bit of kit you're gonna need to make yourself, but it's pretty simple. I go over it a ways into the tutorial. To build it you'll need some lengths of hardwood and some long wood screws)

The last thing you're going to need is a good set of clamps, preferably ones you can open and shut realllllly quickly and with one hand. I like these quickgrips for this purpose.

First thing you want to do is cut the PVC to length. You'll learn to experiment once you've made a few bows, but for now, cut a 58" length of both thicknesses of pipe. Be sure to mark this up and cut it pretty accurately, as getting things offset at this stage can mess up the rest of your build from the get-go.

Be gentle with the saw here, as you don't want to tear up the end of the PVC. Smooth, short strokes will get through it nice and neatly.

Once you're done, clean up both ends of both pipes. Take your file and neatly round out the sharp edges, both inside and out. This may seem like an aesthetics thing, but it'll help guide the PVC to flatness during later stages, so take your time on this one and make sure it's done right.

Next thing you wanna do is take your gaff tape and wrap the 15mm pipe in it, and you want to do so just enough so that it fits nice and snugly into the 20mm pipe without any rattle. Be careful with this, as getting the right amount of tape on there is a bit of an art form. A tiny bit too long and it'll be almost impossible to get it down inside. Also, and this is a pro-tip, keep in mind that PVC pipe isn't exactly uniform in diameter all the way through. For the most part it is, but lots of these pipes have been lying around in the sun for months before you buy them from the shop, so if the tape gives you a super-tight fit at the opening of the pipe, it may damn-near jam in the center, leaving you with an unfixable problem. You're better off having it slide in a little easier than a little tighter, but try and get it as close to that line as you can. If you get stuck halfway and can't get the center pipe in (or out again, to try again) try using a rubber mallet to help persuade it. That trick has saved a few of my bows now...

Important advice: How much tape you use is up to you. I personally am a bit lazy and only wrap the tape around the pipe at seven evenly spaced points. Each end, the center, and then twice in between the center and the ends. This is actually a bad idea, as it leads to all sorts of problems when you're first starting out and you're not used to how the PVC reacts to the heat. The basic rule of thumb is that the more patience you have at this stage to wrap the majority of the pipe, the stronger and easier to work with your bow is going to be.
When wrapping the ends, though, try to leave about an inch of un-taped space, regardless of how much you use, as when the bow is being bent later, this will allow for a little expansion.

Alrighty, your completed pipe should look like this now. Nice and snug and centered:

Next thing you wanna do is to find and mark the exact center of this bow. Since it's 58" long, we need to make the marking at the 29" point. Once you've done that, put a marking 2.5" above and below that point to show where the bow's handle is going to be. You can alter that sizing if you're making a kid's bow, but a 5" handle should suit most adults.

Now comes the interesting part of the build, and that part requires a flattening jig. Basically the jig is a long plank of hardwood that is around the length of your bow. Second to that is another piece of hardwood with a couple of guides screwed to the sides to keep it nicely lined up with the first piece of wood when it's placed on top. Finally, the second piece of hardwood has two long wood screws placed up near one end, and those screws stand up from the wood the same height as the PVC pipe you're using to make your bow. These two screws act as feet to lift the hardwood up off the bow, leaving the other end to touch the bottom piece of hardwood. This creates a perfectly smooth taper which we will use to flatten the round PVC pipe into lovely, smooth bow limbs.

To give you an idea, here are some photos. It's not rocket surgery, I'm sure from the pics you'll be able to figure it out.

Okay, so here's where things start becoming a handful. Get your double-sleeved PVC tube and start heating it up one half of it with your heat gun. Use long, flowing strokes and try your best to heat it up evenly. Don't allow one area to get hotter than any other area. Also don't linger too long in one spot otherwise the tube will melt and burn. You're only doing one half (or limb) right now, so hold the handle of the bow in one hand and the heat gun in the other, slowly rotating the tube as you heat it. Every so often blow some of the hot air down inside, but don't do that for too long because you WILL burn the end of the pipe (it's quite heat-sensitive, being the end).

After about 5-10 minutes of heating, you'll notice that the pipe starts to sag when lifted, but it'll only sag right where the handle is. Don't let it sag too much, though, as this will cause the internal pipe to buckle. A buckle can be fixed, but it's a pain to do and it's far less painful to just prevent it from happening at all.

Once you get to this sagging stage, it's a sign that the PVC "limb" is almost at a temperature which can be flattened, so keep heating it for another few minutes and remember to keep the heat nice and evenly distributed, and occasionally blow heat down inside the pipe a little.

Once you're satisfied that things are pretty floppy, place the bow onto the baseboard of your flattening jig, being careful to line it up nice and straight (and I mean it... Take the time to make it nice and straight. You'll thank me later). Also make sure that the end of the tube is right up against the end edge of your baseboard, like this:

When placing the topboard of the flattening jig onto the limb, line the standoff screws up with the edge of the handle (you marked it earlier). This will ensure that the limb flattening begins where the handle ends. Once everything is lined up nice and straight, lock down the topboard with some clamps and fix it down as tightly as you can.

You'll notice here that I have a clamp right where the standoff screws are, and another right at the end of the jig. This creates a very even pressure across the entire limb. Off to the left of the above picture is the unflattened side of the bow, which we'll get to later. Remember we're not flattening the entire thing, just one side!

Every so often, keep checking the tightness of your clamps. You want the very end of this limb to turn out as flat as possible.

Let it cool for 10 or 15 minutes and then take it out. You'll notice that the limb now smoothly flattens out from the handle to the tip:

One thing you may notice once you've done this, is that a little bit of the internal pipe has now been squished out of the end, like in the photo below. If it has, now's a good time to saw it off or file it back:

While the limb is still warm (and you may need to warm it back up a little to make this work) sight down the limb and make sure it's straight. If you were too quick or rough getting the thing into the jig after the initial heat, you'll get wonky limbs like this:

If you get this, DON'T LEAVE IT. Leaving limbs like that and then using the final bow can lead to the bow just springing apart on you while you're using it. I've had it happen and I have the bruises to prove it. Don't risk it. If your limbs look like this, heat it up again (not all the way so that it puffs up again, just enough to give it a good bit of bend) and bend it as straight as you can. Once the limb has been flattened, it doesn't take as much time to heat it up again. Don't heat it up so much that you compromise the nice flattening job you did. Just do it enough so that you can bend it over your knee with a good deal of force. Take your time with this process and get that limb as laser-straight as you can get it.

So now you've perfected one limb, go ahead and follow those same steps with the other side. Only thing to make sure of is to keep things even. Don't flatten the second limb on the wrong side, or at an angle. You should end up with a "lump" in the middle where the handle is, with the limbs flattening out in the same direction either side, like this:

Now we get to be creative. We'll start out with the handle shape. Heat up the handle until it's super soft, and then squish it inwards on the sides, to give you a bit more of a natural grip shape. I personally like to put on a heat glove and hold the hot PVC with my left hand (since I'm a right-handed shooter) and hold it there until it cools.
While you're doing this, also lift the handle up, allowing both limbs to bend forward on the bow. This seems counter-intuitive to have the limbs bend FORWARD from the handle, but trust me on this... If you've seen a lot of bows, the limbs bend backwards, but that's ONLY AFTER they've been strung. Remember that bows are basically just a big spring, so you want to create the springy tension, which means you want to have those limbs bending forward for now. How much bend should you put in? That's up to you, and it is at this point that you'll get to start making choices about how powerful you want the bow to be. The deeper the bend from the handle, the more powerful the bow will be. I wouldn't recommend going overboard on the power for your first bow. Making a weaker bow first off will lead to much more success for you as a bowyer.

A couple of pro-tips here for you, as this step is a deceptively crucial one in the bow-making process:

Pro Tip 1 - Don't make the handle too narrow. This will weaken the bow. Make the "squish" only slight.
Pro Tip 2 - Don't leave the handle round. You'll actually be left with a very uncomfortable bow which gives you hand-cramps, and it will leave your limbs less flexible.
Pro Tip 3 - It's SUPER easy while doing this stage to end up giving the bow a curve, turning it from a straight bow to one with a massive lean to the left or right. If this happens, re-heat the handle and seat it correctly. You don't want a bow with a bend in the wrong direction. All of your bow's curves should be along the forward/back axis, not the left/right axis.

Finally, you want to make sure that your tiller is even. What's tiller? Tiller is the bow's flex curve. When it's being put under the tension of a simulated "draw", how much does one limb bend in comparison to the other? If they're both the same, then the bow has been correctly tillered. At this point, if one limb is tillered more than the other, it's because the angle between the handle and one limb is greater than the angle between the handle and the other limb. You can often see it clearly by holding the bow up like this:

Once you've got your tiller correct, sight down the bow between the tips to look for any incorrect curvature. If you see it, be sure to re-heat and bend it out. Get that bow looking straight as an arrow (excuse the pun).
When you sight down your bow, here's an example of what you DON'T want to see:

See that? More twist than a 50s diner. You have to sort this out now, before moving onto any more steps, because this WILL cause a fatal error with the bow which may - after subsequent steps have been done - become irreparable. Resolve it now, no matter how excited you may be about shooting your new bow, and save yourself some pain.

Sometimes, sighting down the entire bow can be very tricky to navigate, so try it one limb at a time first, which can help spot which limb your problem is in. Once you've done that, you can analyze the handle and fix any problems there. Check this out.

One limb on this bow is pretty much good to go:

The other limb, however, is crooked, and needs fixing:

Once you're done, the bow should stand up under its own tiller, just like this. If it falls over, it's still uneven:

Alrighty! Nearly done! Now it's time for your string nocks. There are a TONNE of ways you can do these, but I'm going to show you the simplest and most basic, as it's quick, it's easy and it is quite forgiving if your bow is still a touch wonky.

Mark out the limb tips like so, to create a taper of around 45/50 degrees:

Then cut the angles in as evenly as you can (I suck at doing this, so do as I say, rather than as I do) Having something like a scroll saw or a bandsaw makes this job much, much easier, but I prefer hand tools. Also make sure you replicate this as closely as you can on both ends of the bow. I've done this enough where I can just do it by eye, but you might want to measure things out just in case.

Once they're cut, take some time to grab a file and round off all of the sharp angles. This will prevent string-snag and make stringing your bow 50x easier than without it.

Now, just below your tapers, mark out where your string nocks are going to go. Don't make them too deep or you'll never get the string off, but also don't make them too shallow or you'll never get the string to stay on (at least on this type of bow). Once again, make sure they're evenly measured on both ends of the bow otherwise you'll undo all of your awesome tiller work that you did before:

Once they're marked up and you're happy with them, drill some small holes in the center of the nock points, taking it nice and slowly so as not to crack the PVC:

Then, using a saw, cut at angles in from the edge of the bow down into the holes, creating a "cup" shape for the string to sit in:

We drilled holes first because it gives less friction to your string. Don't be tempted to just saw a V shape into either side, as it will lead to undue string tension and potential breakage. Also, round, smooth corners mean a stronger bow, and you're far less likely to see any cracking over time.

Once your nocks are cut, take a smaller file and smooth out all of those sharp edges and make the entire nock area as smooth as a baby's bum to protect your string:

Now you CAN skip this next step if you'd like, but to give your bow a little extra power, you can give it a touch of reflex. Heat up under each limb tip, being SUPER careful not to heat up the tip itself. Just heat up around 4 inches down from the tip until it's a little bendy, and then press the tip down, facing towards the front of the bow. Make sure you're bending this in the right direction, by the way. Do this the wrong way and your bow will be rendered useless:

If you've done it right, your bow shape should look like this. If you can't picture it just yet, the part of the bow which will be facing YOU when you're shooting it is the part pointing upwards in this picture. So the reflexed tips are pointing OUT and AWAY from the shooter.

Now we're going to add just a little bit of deflex to the bow. Don't try and skip this step, as you need to show the PVC which direction it's meant to bend in. Basically what you're going to do is heat up each limb and bend it ever-so-slightly in the direction it's MEANT to flex in, giving it a very slight curve. This will help guide the natural flex of the bow when drawn and allow you to have a really smooth feeling draw.

How much deflex should you add? That's up to you. Personally I only like to add a tiny amount. Just enough to help guide the bow. But if you decide to add more, it's a great way to lower the power of your bow at this point, just in case you wanted to use it more for just fun target shooting and less for hunting or other high-powered needs.

Here's the deflex I added, just so you have a point of reference:

It's important to make this curve a wide, flowing one, and not a sharp bend. You might get frustrated or impatient and bend the limb too hard after heating it, which will lead to a buckle. You don't want that. Bend it gently, in small stages, to achieve a gentle curve that flows the length of the limb. Here's another angle:

As with all of the other steps in this tutorial, consistency is key here. Make sure that whatever curve you put into one limb ends up mirrored in the other limb. Here's what the final shape of this bow looks like after I've done that to both limbs:

Next all you have to do is to make a string out of your paracord and string up your bow, like so:

I won't go into making a bowstring here, as using paracord to make one is fairly self explanatory. Just have a play around with lengths. For best performance, the distance between the handle of the bow and the string needs to sit at about the width of your clenched fist plus the length of your thumb. So do a thumbs up inside your bow and you'll see if your string is too long or too short, then adjust accordingly.

A note on using paracord as a bowstring. Paracord has many uses, and is a great thing to have on you, but it actually makes terrible bowstring material. Why? Because it stretches. It stretches quite a bit. Now, that doesn't mean it CAN'T be used as a bowstring. You'll just have to keep shortening it over time. I do this by tying knots in it. Each overhand knot you tie in the string shortens it by around 3/4 of an inch.
One thing paracord is very good for is to use to find out the correct string length of your bow. Once you've found it, I highly suggest making up or purchasing a proper string. I won't go into details of that here though, as it's a whole other story to do that. Bowstrings are complex beasts, but fun enough to make if you have the time and patience!

Anyway, have a play around with the techniques described here. Making various changes and using other various techniques, you can come up with all kinds of different bow shapes, sizes and powers. It's a lot of fun and I highly recommend it.

I do this quite regularly now and sell the bows, so if you're on Facebook, please look up "Norton Bows" and give the page a like. Every time I finish a new bow (and I decorate them with paint and proper grips, etc) I put them on there to sell.

Anyway, have fun with this, and definitely show me if you make one, as I'd love to see it!

- CumQuaT

1 comment:

  1. I know this was years ago, but this is great, and SO HELPFUL. I wasn't sure if it was possible to make PVC bows in Australia after learning about the PVC problem, but this gives me hope again. THANK YOU. =]