5 – Shaft Reduction and spine qualities

Shaft reduction is a very simple process that is used to bring a shaft down to a size that should have favorable spine qualities. There are several different ways to do this. You can reduce your shafts total primitive using stone flakes and stone tools or using metal hand tools. Some have used a metal plate with hole that reduces in size down the plate. The shaft is pushed through every increasing smaller hole until you get a finished shaft. There is the arrow plane with the curved blade that planes the shaft to the correct size.

Some shaft production techniques are not as primitive as me might want to get. There are some using a router table, table saws and other power tools to cut out shafting. They are also not very primitive by any ones standards so I will not cover these at all. Many of these techniques for producing shafts have been explained in traditional archery books are available for you to find in those books. I will go into the various different ways to produce primitive shafts using all primitive tools and steel hand tools.

Spine qualities will be covered in the back section of this chapter. I realize this might be one of the driest sections in the book. It is the most technical one at least. I tried to keep out of the technical aspects of all this when I first started playing with primitive archery. I said that I wanted to be all aboriginal in my approach and did not need math and physics to perform my tasks. And at first I was able to perform with out these understandings. I was not able to perform the very well but, non-the less I muddled through. As I progressed on in my experience I learned to be a good bowyer or arrow smith you must at least understand the physics and make it work for you to have good equipment and to ultimately be a good archer. So take your time and read that back section carefully. It really is the most important section for producing good arrows.

The first shaft production method we will cover is the  progressively smaller hole plate. It was used by colonial tradesmen to produce doweling and could be found in reference material of this period. The plate performed this task by forcing a piece of wood stock through ever-increasing smaller holes. This shaved the stock down until it was the correct size needed. This is a nice traditional hand-made approach to making wood arrow from hardwood stock. The only draw back is the wood stock must be cut on a table saw unless it is very straight and can be split out with a frow.

Colonial type dowel maker 5 - picture 1Picture 1

The arrow plane with the curved blade is some times called the Strunk Plane, as one is made by John Strunk and his company the Spirit Longbow, Inc. The arrow plan simply holds the wood stock in a V channel and slides a curved blade from the plane over the stock to reduce it to proper size.

Picture 2
The Strunk Arrow plane5 - picture 2Picture Courtesy of Three Rivers Archery

There is the totally primitive way of using stone flakes as scrapers and a sizing tool. A sizing tool is as simple as a piece of bone, antler or stone with a hole bored through it. This gives you a way to check the shaft for a uniform size across its entire length. You would check the shaft by sliding the it through the hole and seeing which parts are too thick to slide through. Then you would remove the shaft and reduce these thick spots to produce a uniform shaft. The slide them back into the sizing tool to recheck them. The shafts will all become very close to the same size and should spine closely in spine and may only need slight adjustment after test shooting to lower heavy shaft to get them all shooting alike. Picture 3 show a piece of antler with a sizing hole bored through it. The arrow is being slide through the hole to see what areas need to be reduced. Picture 4 shows a stone flake being used to scrape and reduce a shaft.

This is the way some primitive people’s produce their arrow shafts. Most woods when reduce to the same diameter will spine close to the same or at least with in ten pounds of each other. This way once you found a sizing stone that had the correct size hole to produce shafts at your spine and higher you could easily just scrape the center of the shafts on the heavy ones and get them all to shoot the same.

Picture 3   5 - picture 3
Picture 45 - picture 4

Some primitive arrow smiths used two flat pieces of sandstone as shown in picture 5. These two piece were notched to fit together as one piece. They also had a groove down the middle of each piece in the shape of a half circle. When the pieces are locked together they form the full circle. The shaft would be place between the two halves and the arrow maker would slide the stone back and forth. The stone would sand the shaft the proper size when the two stones were touching. This style is one way used by some American Indian tribes.

Picture 5    Sandstone abrading blocks5 - picture 5

Some Indian tribes used a sandstone abrading tool similar to the one showed in Picture 5 but, it only was one-sided and a little simpler made. Usually constructed from a larger palm sized stream stone and had a half circle groove cut into the stone. This was used to run up and down the shaft to sand the shaft and reduce it in size. These where and still are used to generate heat through friction to perform straightening. I have seen other archers use smooth softer stone such as green stone with a similar groove in the stone. The stone will not reduce the shaft but will generate heat due to friction. This heat will usually get the shaft hot enough to do small amounts straightening functions but does more work compressing sections of the shaft and perform straightening.
You could use a thumb plane and reduce all sides of the shafts on a flat surface until it spines properly. This will give you a shaft that is about uniform and parallel. Or you can use more primitive tool like a scraper, a pocketknife, and a flint or glass flake to scrape off extra wood. Once the shafts are with a pound or two of spine they can be sanded to round out the hexagonal look to them and only reduce spine by maybe a pound.

At some point in the reduction process you will either need to use a spine tester or learn to find some way of testing your shafts for proper spine. If you make enough arrows you will be able to just flex the shafts and be able to guess the approximate spine range of the shafts. This will only get you close and you will still need to most likely have to use a longer arrow and cut it down to get it perfect. It has been said that many American Indians use this way of flexing and checking the spine by feel. They had some arrows that shot great and some that did not shoot as well. I really can not find other references to their ability to check spine, but it has been recorded plenty of time about how accurate they could be with their shooting. Many tribes had an elder than did nothing but make arrows. I would have to think that he understood how to reduce the arrows he made to proper spine to make them fly properly. It would have been an incredible waste of time and valuable feather to produce so many arrows that are of the wrong spine and do not fly well. I also do not think that if they where producing arrows out of spine they would have been very accurate in their shooting.

A simple spine tester can be made by placing two ‘Y’ stick in the ground about 26” apart. The shafts can be placed across the two sticks and have a rock, or similar weight, to hang on the shafts. This will provide you with a consistent weight to give you your angle of deflection. You would need a back plate to check them against. The back plate would have a line scratched on it to show the proper amount of bend or deflection you will need. If the arrow does not bend that far it is too heavy. If it goes past it the shafts is too light. This type of spine tester would need a shaft that is to your spine and shooting correctly off your bow to make the line to compare the other shafts against.

On the next page is spine tester dial showing a deflecting to spine for an arrow I was making. This spine tester was made from an article in “Primitive Archer” magazine volume 3 Issue 3. The article was written by Billy Rudd and was called “Poor Man’s Spine Tester”. I would like to thank Billy at this time for writing the article as it helped me immensely as my do it yourself attitude would have held me back without this easy to make spine tester. The original article was printed using a measurement of deflection of inches and you need a calculator while using the spine chart. On the next page is a picture of the spine tester and the revised chart for the article. You will only need to get the back issue of the magazine for building directions and follow the chart I have supplied

The Converted Spine Chart
5 - picture 6-1Poor Man’s Spine Tester5 - picture 6-2Picture 6

No matter how you check your arrows for spine you need to make sure they are matched in spine quality for your bow. You can not be a consistent archer with inconsistent arrows or arrows that are not spined for you bow. A bow that is not center shot or slightly off-center, as most selfbows are, would need an arrow of lower spine than a completely center shot bow would need. Picture 8 shows a self-bow with a full width handle and shows the amount an arrow can be pushed of center.

A center shot bow does not need the arrow to flex to get around the riser or handle section. Picture 7 shows a center shot traditional recurve. By not requiring the arrow to flex around the riser it can use a higher spine and may actually perform better with an arrow of the same weight as the bow is in pounds. So the spine relationship for a selfbow, or other non-center shot bow, is more critical for good arrow flight.

5 - picture 7Picture 7 Center shot bow
5 - picture 8Picture 8   Non-center shot bow

If your spine is too high or too low in spine it can make your arrow track to the left or the right respectively. So you can see that an arrow that is spined too high will shoot an inch or several inches to the left while an under spined arrow will shoot to your right of aim. If your arrows are not matched you will not be able to form a general point of aim to be consistent with all you shots. You would have some arrows shooting left and some arrows shooting right. You might be able to learn to consistently shoot over or under spined arrows in a group but not a combination of the two. You might be able to adjust your shooting to compensate for these mistakes. Although, if your arrows are not matched closely they will not group closely and you will not become consistent in the way you are shooting. So take your time and develop a setup for measuring spine using one form or another.

For myself I prefer a spine of 10 pounds under the weight of my selfbow. I think this helps it clear the bow and be on its way better. Some archers prefer to use longer arrows to perform this same function. By using arrows that are longer the effectively lower the spine of the arrow about 5 pounds for every inch the arrow is longer than it is drawn. The longer arrow is a good way to match spine or make arrow fly good-by leaving them long and cutting off an inch every time until the start to fly properly. Leaving the arrow a little longer is also a good way to get good arrow flight with lighter points like bone and antler. The bone and antler will not weigh as much as steel and will not make the arrow flex as much when it is shot. This, in effect, actual makes the arrow shoot as if it is spined stiffer than it actually is. Consequently, an arrow that has a heavy point, like and English war bodkin, will make the arrow seem as though it has a weaker spine than it actual does.

There are several terms we should go into now for the explanation of spine listed above. Some of these references are in relation to static spine or dynamic spine. You will need to understand the differences of static and dynamic spine in order to make arrows that work properly for your bow.

Static spine is the shaft’s spine or bending qualities on a fixed immovable object. This could be referred to as a spine tester, a weight hung on a shaft or just flexing the shafts across your neck or between your hands. Static by definition means at rest or without movement. So any type of arrow flex test without shooting the arrow or being placed in motion is considered a static measurement.

The length, thickness, particular stiffness of the shaft material and the force of the bow used are the only forces that affect the static spine. Lets compare two shafts of the same material against one another. The one arrow should be two inches longer than the other should and they should have the same stiffness and diameter. The longer one will have a lower spine on the spine chart. Even thought they have the same static measurement the chart has been calculated to show how they will perform differently under the dynamic forces imposed by the bow. The relationship of the longer arrow will change about 5 pounds in spine per inch of change in the arrow length. So, as shown just now we have an arrow that will respond as if it is ten pounds lighter in spine when it is shot. Even though these arrows are the same diameter and have the same stiffness they will perform differently when shot out of the same bow. Consequently, an arrow with one inch cut off its length will perform as if it has been increased in spine by 5 pounds.

Now on the other hand we have dynamic spine. Dynamic, by definition, is the force applied to the arrow in relation to motion, hence shooting the arrow. We use static spine as a relationship with dynamic spine as a way of calculation spine to choose the best arrows. There are many factors that change the dynamic spine qualities of an arrow. These would be arrow length, arrow thickness, material stiffness and the force of the bow which are the same a static spine. There is one more factor that affects the dynamic spine and that would be the arrow point weight.

Starting with the weight of the arrow point and how it affects the spine of the arrow. If you increased the weight of the point it would in effect make the arrow perform as if it has a weaker or lower spine. To understand this we could look at the physics of this relationship. The larger a point is the more force it takes to make it move from its stationary position. As this force is applied and more of it builds up to move the large stationary point it makes the shaft flex more than a lighter point would. This is how a heavier point lowers the dynamic spine of an arrow. Again this would also have the same and reverse effect using a lighter point for the arrow. The lighter stationary point requires less force to move it from its stationary position. A smaller force used in moving the point will make the shaft flex less and make it act as if it has a stiffer or higher spine.

Now to put this to practical application we will compare what I wrote above to weight of arrow points. The accepted weight of an arrow point is about 125 grains for our normal spine charts. If you increased the weight of the tip closer to 150 grains you would lower the dynamic spine about 5 pounds. The same is true if you lowered the weight of the point to near 100 grains you would make the arrow perform as if the spine had been increased by 5 pounds.

As you can tell by now there are more than a few factors on each arrow that change the way that arrow performs. You will need to take your time and evaluate this chapter closely if you do not already understand all of the topics covered. The most important part of good arrow making is proper spine. If you do not remember and absorb all of this and use it in your arrow making it will be very difficult to become a good arrow smith.

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