Not so elaborate on the how to here. I'm baking a cake and I think the pic is self explanatory. I got the template by searching "2Jays spine". Had it printed in color.
I had the hard board left over from a home project. The needle is a bike spoke.
The template comes with a "distance A" marked. This needs to be the distance from the center of the needle pivot point to the bike spoke bend at the back where the arrow rests. the arrow rest part should be about center of the jig.
My weight I forgot to photograph but it's a small instant coffee can with playsand stolen from my daughters sand frong thing and a clothes wire hook.
I clamp mine to the edge of my workbench.
You can see how I pivot the scale to zero out the needle and arrow shaft. The weight hangs right next to the needle on the arrow shaft at about center or as close as I can manage.
