This is a tutorial on making a bow saw in the field. The advantages of this method if that you only have to take the blade with you, which is easily coiled inside a billy pot. When you get to your site you can construct a sturdy saw in about 20mins (with practice). If you decide to keep the pieces, next time it will only take you 2mins to put together. The benefits of a saw over an axe or machete are:
- Safer - An axe is a powerful tool but can very dangerous in the hands of the inexperienced (like me). The last place you want a bad cut or a chopped off finger is isolated in the bush. A saw is much safer, and even kids can use it under supervision. However please be careful when coiling and uncoiling your saw blade, I have wire attached to the each end of the blade that I use keep it coiled in travel.
- Lighter - With this method all you need to carry there is the blade. Even if you keep carry the frame with you instead of making a new one each time, this will be lighter than an axe.
- Tidier- Axes and machetes leave wood chips everywhere which definitely violates leave-no-trace etiquette. If necessary to cut from a living tree a saw leaves a nice clean cut which looks tidier, and wont be as likely as a rough cut to allow diseases to enter the tree.
This is a very simple design that is held together by the same forces that tension the blade. Once the bow saw has served its purpose you can dismantle it and either use the frame as firewood or keep it for for next time. These are what you will need:
- A knife (Use a piece of deadfall as a baton on the back of the blade to made larger cuts easier)
- A 2m length of paracord (or other strong cordage)
- A bow saw blade. These can be bought from most hardware or gardening shop for under $8
- Various lengths and diameters of deadfall for the frame
Cut yourself the following sections for the frame (see picture above).
These specs don't have to be precise, and depend on the strength of your wood. The side arms need to be strong because they will take all the tension. The length of the cross piece is important but it depends on your saw blade. If in doubt err on the long side, you can always trim it!
- 1 crosspiece - about 20mm diameter, and 20mm shorter than the length between the most distant holes in the saw blade
- 2 side arm pieces - about 30mm diameter and 250mm long
- 1 tensioner (not in picture) about 12mm diameter and 200mm long
- 2 stoppers (not in picture) that will go through the holes in the blade. These should be from the strongest wood you can get because they are limited by the diameter of the hole
Time to split the side arm pieces to hold the saw blade. This can be easily done with your knife and a scrap piece of deadfall as a baton to tap the blade into the grain. Split twice the length that you actually need so that the blade can be jammed in easily, if you are worried that the split will travel too far you can firmly bind the piece with cord where you want the split to stop.
Now you can cut the notches that will house the stoppers and lock the blade in place once it is tensioned (see pic below). Mine are pretty rough as mine was to be fire wood after it served it purpose. You will need to cut the stoppers from a strong season branch as mine were on the damp side and begun to crack after prolonged use. Shave them to just fit through the hole, maximising their diameter and corresponding strength. Alternatively two bolts or nails could be used, but I prefer to carry as little as possible. Once these are cut you can test the configuration, it should look like the pic below. Ignore the piece of wire, it is used to coil the blade up when it is stored.
This is the most tricky step and you may have to come back and work this part again as I did. Basically you are cutting the crosspiece ends and notches in the side arm so that they constitute a solid frame when the tension is applied. The photo below is what you are aiming for. With hindsight I would increase the distance between the notches and the blade because this is the factor which limits the thickness that you can cut with your bowsaw. However increasing this distance will also reduce the level action of the tensioning so be careful.
I made the mistake of cutting the ends of the crosspiece to fit the arm piece notches perfectly. Then when it was tensioned and the angle between the two pieces changed, the pieces popped out of place. I had to go back and cut the notches as in the diagram.
The picture below is what you should end up with, keep in mind that the photo was taken before I had to cut the notches bigger.
Now the fun part. The paracord will be looped around the tops of the side arm and twisted tight so that the saw blade will be tightened via lever action.
First cut some small notches so the paracord wont slip off the top. Make a loop on one end of the cord, a figure of 8 or a bowline works well. loop it around the arms until you run out of cord and tie it off around a side arm as shown in the pic above. Insert the tensioning stick between the strands and twist to tighten, as you can see I made my stick too long so when done I had to cut a notch in the cross piece to hold it out of the way of the blade. I could have instead just cut it shorter.
You now have a bowsaw! Holding it closest to the blade puts the least stress on the frame when in use, but it should be solid enough to stand up to anything. Below I am cutting up some firewood from a fallen pine tree. It may seem obvious but its a lot easier to start at the end of a branch and cut you way to the base, so that each time the section you are sawing is stable. Good luck, let me know how it goes by commenting below!