I have thought about a cheap laser arrow spine tester for a while. Having found that you friendly auction site sells 1w laser pointers for less than ?3 I thought I would have a go.
It appears to work really well. It is very sensitive to spine variation. I'm in the process of calibrating it using a digital caliper, but for now it allows me to check how well matched my Cartels are.
The laser is suspended from the arrow undertest at one end. The weight, suspended below, is a calibrated 2lb bottle of water and hung from the midpoint through the base board. As the arrow bends under the weight the laser dot moves along the base board, currently on a linear (rule) scale, but when calibrated it looks like it will be a logarithmic scale.
Total cost approx ?6
It appears to work really well. It is very sensitive to spine variation. I'm in the process of calibrating it using a digital caliper, but for now it allows me to check how well matched my Cartels are.
The laser is suspended from the arrow undertest at one end. The weight, suspended below, is a calibrated 2lb bottle of water and hung from the midpoint through the base board. As the arrow bends under the weight the laser dot moves along the base board, currently on a linear (rule) scale, but when calibrated it looks like it will be a logarithmic scale.
Total cost approx ?6