Basic Bow Construction

By D Stalter - http://www.geocities.com/Yosemite/Trails/9408/selfbow.html

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There are several types of bows. All are basically similar. The RECURVE is a bow that has the tips bent backwards from the draw. This gives the bow extra power when drawn and increases arrow velocity. The BACKED Bow is primarily wood, but has a thin strip of another material along the back of the bow. The COMPOSITE Bow is made by laminating layers of material. The SELF bow is usually made from a single stave. The American Indian bow usually measured between 60” and 75”. We will be making a 68’ SELF BOW using whitewood. When choosing your wood, there are many things to consider. We always hear that Yew and Osage Orange are tops. While they are an excellent choice, they are not our only choices. When you work with Yew and Osage, you must remove the bark and the outer sap wood to produce a quality bow. With whitewoods, just remove the bark and there is the back of your bow!! Whitewoods are easier to find, easier to work, cheaper and you have more choices. So what is the drawback? A whitewood will develop string follow. String follow will decrease your arrow speed. But, we can make adjustments for this when we build our bow. We can make it 25% wider at its widest point. We don’t have to worry about changing the thickness.

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The Stave

Although it is possible to use wood from a lumber yard, it is ideal to cut and dry your own. Wood from a lumberyard has probably been kiln dried, which can be OK, but if done too quickly or dried too much, it can weaken the wood.

If you take your wood from a tree, try to cut it after the first frost. Mid January is best. Once it is cut, leave the bark on the stave and paint (latex) or wax the ends. Put your wood away in a warm (not hot), dry place to season for at least 3 months.

After the log is seasoned, split it into staves.

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Stave Prep

Ideally, staves should be split from a log at least 6” in diameter. Moisture content should be between 8% and 9%. Three Rivers Archery sells a reasonably priced moisture meter. The closer you are to your final dimensions, the faster your bow will dry. I would recommend that you work with hand tools. If you try to use a saw, you are more likely to saw across the grain. The more the stave follows the grain, the stronger it will be.
When your moisture content is down to 8-9%, it is ready to work.

Working the Stave
The back of the bow will be the side which is closest to the outside of the tree. If sapwood is used, it should be less than 1/3 the total thickness of the bow. The back of the bow should ALWAYS follow the grain and the belly should follow the line of the back.
Since we are working with Whitewood, all we have to do is remove the bark and we have the back of our bow.

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Marking the Bow

1. Using a string line, mark a line directly down the middle of the back of the bow, the full length of the bow.
2. Use your tape measure and mark the middle of the bow. (A) (I am making a 68” bow so my mark is at 34”)
3. Measuring from the middle, make a mark 2 3/4 ” above the center mark (B) and another 1 1/4” below the center mark (B). This will be the handle area, with the upper limb 1 1/2” longer than the lower limb.
4. From your handgrip marks, measure 3” on both limbs (C). This mark will become our widest part of the bow and will remain wider for 12” before tapering down to our desired width (C-D)
5. Go ahead and measure this 12” on both limbs now (D).
6. We should now have all the marks we need on the length of the stave. We can mark our bow width now. Each of these marks will come off our center line.
7. At your handle (B-B), mark 7/8” each side of center line, making the handle width 1 3/4”.
8. We want the widest part of the bow to be 2 1/4”, so mark C-D at 1 1/8” each side of the center line.
9. Using a straightedge or string line, draw a line connecting B to C.
10. The tips of the bow will be 5/8”, so make your marks 5/16” on either side of the center line at both ends and connect these marks to (D)

You should now be able to see the outline of your bow. Start working the bow, staying outside the lines. As you get close to the lines, smooth it with a plane and sandpaper.

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Working the Belly

Looking at your bow from the side, we want the depth of the handgrip (B-B) to be about 1 1/4”. It should then taper down to about 1/2” at (C) and stay 1/2” to the tips. Once you have this accomplished, you can begin tillering.

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Floor Tillering

Tillering is removing wood from anywhere that it is not bending enough (And staying away from spots that bend too much). Start by rasping the length of each limb. After you have taken off a little wood, stand the bow on the ground and grasping the top of the stave with one hand, press against the handle with the other. Continue using the rasp until you have both limbs flexing about 6”.

Now we come to the 'fine tuning' part. This is the most important part of building a good bow. Place the bow in your vise, belly up. Using a drawknife, spoke shave, wood rasp, or even a pocketknife with a very sharp blade, start shaving layers off the belly starting at the handle and working toward the end of each limb. Keep testing the bend using the 'floor tillering' method until you think you are getting close to where you want the weight of your bow to be.

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Cutting Nocking Grooves

Before using a tillering stick or a tillering board, we need to cut the nocking grooves into the ends of the limbs. Hold the length of the stave away from you. Using a 5/32 circular rasp or something similar, carefully cut your nocks 1/2 inch in from the end of each limb. Remember that you want your string to be centered. Most important, do not blemish the back of the bow.

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Bowstrings

You will actually use two bowstrings. The first one will be heavy and very long so that you can just slip it over the bow without flexing the bow. The second string will be your actual bowstring which you will use near the end of the tillering process. The final bowstring will be 3 inches less than the length of your bow from nock to nock. A self bow should have a brace of 5 or 6 inches.

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Using A Tiller Stick

A Tillering Stick is a board that you will use for precise tillering. If you plan on building a lot of bows, you may want to build a tillering board, but we can make a tillering stick easily.

1. You want your stick to be longer than your intended draw length. (40-45 inches works good)
2. You can either cut slots into the stick every inch or put posts into the stick every inch. These are what you will use to hook your bowstring in when checking the tiller.
3. You will need to cut a bow-rest out at the top (or put posts in) to hold your bow on the tillering stick.

The bow will rest on the top of the tillering stick and the string will be hooked on the marked posts. You will need to check often as you tiller your bow. Work your bow gently. Gradually working into your bend, flexing it slightly further at each stage of your tillering work. If you are intent on checking your weight, and forget to check for a consistent curve, you will not get the bow you want. Always remember to step back and check your work. Make sure both limbs are bending equally. You should check for curve before you check for weight. If this is your first bow, you might not want to even bother with getting an exact weight. You will work down the tillering stick from each 1 inch mark, gradually shaving off wood where the bow is not curving evenly. If you are using a scale, you want to stop tillering when your bow weight is 3 or 4 pounds higher than desired. Your final finishing and initial shooting will cause the weight to drop a couple of pounds.

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Finishing Touches

Give your bow a light sanding and seal it with a polyurethane coating. I just hang my bow from the rafters in the garage and put three coats of spray polyurethane on it. A coat of car wax applied will also insure that you have a waterproof bow. When it is dry, I wrap the handle in leather and I am ready to shoot.

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Backing

If you decide to back the bow, sinew is the best material. I will post an article on how to back a bow soon.

Thank you for reading this article. Remember that there are many ways to build a bow. If you use some of these and some of those, you will end up with a bow. Use what works for you.