Spin Testing

[zinndl]

Would someone explain spin testing to me? How it is done, it's purpose and how necessary it is. Can it be done without the use of a spin tester? I was told that you could spin an arrow on it's tip (upright like a top)and check for wobble; is that true?

[Yolla Bolly]

I will give it a shot, bro.  I have seen the term applied to 3 different techniques.
The old timers would place the tip on a hard surface, with the arrow vertical and give the nock end a spin.  Observing the shaft, head junction would show a wobble if the the shaft was not straight or the head was mounted crooked.  But this only works with "needle" points---the chisel tip on my broadheads induces a wobble independent of the shaft.
Another technique is to rest the shaft in a "vee" formed by placing a thumbnail  against the palp of the index or long finger, then spinning the other end.  A straight shaft will just spin, a crooked shaft will jump up out of the vee.
One can also rotate a shaft slowly in some type of jig, consisting of paired  v-blocks or juxtaposed rollers, with some reference point positioned near the end---a straight shaft will show no up and down movement of the tip (or nock).  The bow catalogs sell a couple of models, and some shaft straightening devices and spine testers incorporate such a jig.

[Apex Predator]

I can spin the tip of my arrow on a smooth surface and see gross errors in alignment.  In order to fine tune my broadhead alignment I must spin them on the palm of my hand.  I can feel the slightest wobble.  If they are not right, I make an adjustment and try again.  Never used one of those spinny thingies.

[bigcountry]

You can see .01" wobble with the top spinning.  Do it on a light colored surface.  Kinda hard to see anymore than that.  Spinners are cheap.  Like 10 dollars.

[ishiwannabe]

Spinners are really cheap if you make one. All ya need is a piece of wood about 36" long, four nails and a reference line. I have a couple and the work just as well as the ones I paid for.
Spin testing is great for carbons and aluminums. It can work for very straight woodies, but it will pick up any deviation in the shaft too. A woody doesnt have to be perfectly straight to fly well. It helps of course, but isnt absolutely necessary.

[zinndl]

If you dectected misalignment with a carbon arrow / broad head combo how do you correct it?

[Apex Predator]

I just heat the point and spin it slightly on the steel insert.  If you used epoxy, it might be permanent.