I bought some new arrows (about 8 months ago) and it appeared that I had some flyers and I needed to know if it was me or the arrows. I finally got around to building this tester, which has been on the to do list for quite some time. Usually those flyers are me but in this rare instance it was in fact the arrows. Several of them were way out of factory specifications so my time invested in building was totally worth it.
So here is my Spine tester/shaft spinner. This spine tested can test a 28" shaft and it has a weight to spec of 880 gram weight or 1.94 pounds. The steel weight sits in a tube and presses down from the top of the arrow. Not shown in the pictures is a slider that holds the weight up when changing arrows. the only really different design part of it is the rubber wheel I added to help me control weight on the shaft as I spin it. It seemed no matter how careful I was when using my finger spinning the shaft I always seemed to add a little flex in the shaft while spinning. This flex transferred to the dial indicator giving wildly inconsistent results, it just seemed to bounce all over the place. By adding the wheel and using it to spin the shaft it helped to make it a lot easier to apply targeted pressure and to rotate the shaft with less interference.
As you can see, like most of my work, I left the rust\oil patina and mill lines on the unit to give it that home built character that a true DIY'er would appreciate. OK OK the truth is I'm a lazy old fart that can't be bothered to paint anything once I get it in working order.
*** Note how huge that weight is, 2 pounds is a lot of steel! ***