Bow Making

Next to all the research we try to do in various fields concerning clean energy and the likes, I figured it is also important to do something else... As long as it conrtibutes to the gathered knowledge here.

 So I decided to make a bow. The technique I'm using is quite old, but not simple. And it is a nice challenge to use our 'modern' machines in the processes involved.

The bow I'm making is called a recurve bow, which looks like this:

Recurve, because as you can see it curves back inwards at the ends.
The bow will be made from wood and fiberglass, strips of which will be laminated together and pressed into a bow from. So first I milled out the bow form with the Shopbot (you can use a smaller CNC machine of course). This shape you can see later in this project post, when the strips of wood will be pressed in there.

The bow will be made by laminating  strips of wood and strips of fiberglass together, and then shaping tha handle and nock with hand tools or a CNC machine.

 So how to start? First we obviously need wood. Birch is good to use, and seeing it comes in complete woods here, not a problem to find. If you use another type of wood, make sure it's strong but flexible. Wet wood is always more flexible, so if you buy wood, you might want to soak it in water before using.

I did not buy wood though. I just grabbed an axe and when out into the woods:

With this nice tree chopped down, I could get to work.  Sinse trees here in Norway are somewhat round, I needed to plain the tree first. I need strips of wood for the laminating process.

So I set the Shopbot up for plaining the wood. I strapped part of the tree together with some straight ends, and mounted a big plaining tool, as you can see here:

 Tools like this are made for plaining only! So you can not do plunge moves with them (i.e. drill down into the material) If you use tools like this, make sure your tools starts at one of the sides of the piece to be milled, instead of on top.

the milling setup was like this:

In the procces:

 After the plaining, I drew the lines for the strips in Illustrator, and then exported them as .dxf files. The shopbot software handles these best, I discovered, and using partwizard I created the toolpaths for cutting the strips. 

Next, using a 1/4 inch balnose tool, I cut the strips out of the tree:

After that I also made the pieces for the handle of the bow. 

I now had 7 pieces for the bow (not yet the string reinforcement pieces, and the fiber):

So next step was to glue the handle parts together. I used regular wood glue, the stuff you get at your local shop will do fine, but don't hesistate to spend a bit more money if they have different variaties.

Make sure the strips are completely covered in glue, and then clamp them strongly together:

Make sure the centers are positioned exactely on top of each other. Just measure the pieces and mark the middle with a pencil.  

Allow the glue to dry for at least 24 hours before you continue on the bow.
You handle should now look like this:

After that, I  did draw a curved line, starting at the location where the most left side of the middle piece is attached to the top piece, rising to the top and the exact middle of the top piece, to come down at the most right side of the middle piece. This I used to mill out the handle so it would be completely smooth. You can do this using a CNC machine, as I did, or just a regular bandsaw. The pro of the CNC is that you can be more accurate, the pro of the saw is that it is quicker and slightly easier to set up.

I chose the CNC:

For the next step we will be going to a fiberglass facory to get the other strips laminated into the wood.

Check back later for more...