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Main Boards => PowWow => Topic started by: canuck4570 on February 18, 2015, 11:30:00 PM

Title: spine testing machine
Post by: canuck4570 on February 18, 2015, 11:30:00 PM

indexing your nock with a spine tester, does it make a lot of difference in accuracy

Title: Re: spine testing machine
Post by: Bud B. on February 18, 2015, 11:57:00 PM

If with wood, yes. Assuming you're speaking of spine accuracy. Shooting accuracy? yes as well. Wood spine reading will be different if your grain is not perpendicular with the spine mechanism. (Up/down) Pull against the growth ring grain.

Title: Re: spine testing machine
Post by: warden415 on February 19, 2015, 06:32:00 AM

It does make a difference  with carbon as well. Maybe not as drastic as wood but still varies a few lbs based on orientation  of how the shaft lays on the tester

Title: Re: spine testing machine
Post by: canuck4570 on February 19, 2015, 07:06:00 AM

that said

wich spine tester do you recommend

Title: Re: spine testing machine
Post by: canuck4570 on February 19, 2015, 07:09:00 AM

forgot to mentioned I use mostly alluminium

Title: Re: spine testing machine
Post by: Bud B. on February 19, 2015, 07:40:00 AM

Didn't know that about carbon, warden415. Have you  ever seen a larger variance than just a couple pounds?

Title: Re: spine testing machine
Post by: Bud B. on February 19, 2015, 07:41:00 AM

http://www.3riversarchery.com/ace+spin-spine+tester_i5900-1_baseitem.html

Title: Re: spine testing machine
Post by: reddogge on February 19, 2015, 08:55:00 AM

I use a homemade one.

Title: Re: spine testing machine
Post by: Fletcher on February 19, 2015, 09:55:00 AM

I use the Ace Spin-Spine that Bud linked above, but the others work fine too.  Whichever you use, make sure to zero it before each reading; it make a difference.

FWIW, aluminum is very consistent so don't expect to see much difference in it.  Wood and carbon is another story.

Title: Re: spine testing machine
Post by: V I Archer on February 20, 2015, 01:55:00 PM

I built a real simple homemade one.  There was an article in TBM a few months back.

Title: Re: spine testing machine
Post by: warden415 on February 20, 2015, 05:45:00 PM

Bud B I have not seen huge variances  but 5 lb is not uncommon. . I have read where others have seen greater variances. I havnt had my tester all tgat long so I havnt been able  to. Test alot of different brands of carbon.

Title: Re: spine testing machine
Post by: koochiepie on February 22, 2015, 07:31:00 AM

I use this one
  (http://i1299.photobucket.com/albums/ag72/paulmills1956/1_zps2qbrsnib.jpg) (http://s1299.photobucket.com/user/paulmills1956/media/1_zps2qbrsnib.jpg.html)

Title: Re: spine testing machine
Post by: Cupcake on February 22, 2015, 07:52:00 PM

I have been wanting to build this for several years and now have had the time to do it.  It is all electronic and both weighs the shaft and spines it.

 http://youtu.be/LCbjCFox8BQ

Each support has a load cell that works just like your grain scale.  The stepper motor linear actuator applies force to the arrow until 2 pounds is reached. The deflection required to reach that force is known so it is simple to calculate the spine.

There is no zeroing required because the microcomputer takes care of that for you.  Just place the arrow shaft and push the button.  It takes about 5 seconds to have the result in weight and spine.

It is very accurate and repeatable.

Title: Re: spine testing machine
Post by: Gordon Jabben on February 23, 2015, 08:56:00 AM

I never notice over a pound or two difference in wood arrows but it may be because I don't spine test shafts in the lighter spine ranges.

Title: Re: spine testing machine
Post by: bigbadjon on February 23, 2015, 10:07:00 AM

The lighter the bow is is more finnicky it is to match your shafts. Every archer who is not spine matching his or her arrow shafts is giving up accuracy and forgiveness, especially on bows under 60#s.