To begin with, let’s get some definitions straight. I often hear these terms used interchangeably, and they are not. It is not accurate to call a car and a truck the same thing, but it is accurate to call them both automobiles. With this in mind, let’s define “spline“, “spine“, and “dynamic spine”.
What is SPLINE?
- a rectangular key fitting into grooves in the hub and shaft of a wheel, especially one formed integrally with the shaft which allows movement of the wheel on the shaft.
- a corresponding groove in a hub along which the key may slide.
- a slat.
- a flexible wood or rubber strip used especially in drawing large curves.
How to measure the Static Spine of an arrow
Just so you know…accurately measuring the STATIC SPINE of an arrow doesn’t mean that this is where the process ends. It is quite normal to manipulare a 36 spined arrow to fly like a 32 spined arrow. However, an accurate static spine measurement allows us to further adjust some of our arrows to group well if necessary.
Manipulating the DYNAMIC SPINE of an arrow, how it performs in flight, is a whole “nother” topic which will be covered in the advanced section.
AND JUST SO WE CAN ALL AGREE…NONE OF THIS INFORMATION MEANS A THING IF YOUR FORM IS NOT GOOD. GET TO THE RANGE AND PRACTICE!
It is very important to know that not all spine testers accurately measure static spines of bamboo arrows. I haven’t tried them all, but Ace Archery makes a very nice spine tester which is generally accurate for bamboo arrows if you take some time and learn to use it properly.
It is important to ACCURATELY measure the static spine of your bamboo shafts, and find where they match one another within the set of 12 arrows. By finding this place, and placing the nock properly to allow you to place the cock feather on this spot, you will find your arrows fly more predictably. However, this is NOT the end of the task.
Later it will probably be necessary to adjust some of your arrows so that they FLY THE SAME. This is the dynamic spine which we will delve into in the ADVANCED SECTION. For example, once the static spines are found and matched, we may find that some of the arrows will need to be shortened slightly, or a heavier or lighter head may need to be placed a specific arrow to match the balance of each arrow within the set as well.
There are 4 major specifications which will need to harmonize on an arrow, AND WITH EVERY OTHER ARROW WITHIN THAT SET to get those “teacup” groups.