Primitive Archer

Main Discussion Area => Arrows => Topic started by: wildman on February 03, 2011, 01:34:01 pm

Title: spine tester
Post by: wildman on February 03, 2011, 01:34:01 pm

I'm sure this has been posted before .Does anyone know of a way to build a fairly accurate spine tester with out costing a small fortune? ???

Title: Re: spine tester
Post by: Pat B on February 03, 2011, 01:55:25 pm

Google James Hill Spine Tester!  Cheap, easy to build and accurate enough for me and Art Butner!  ;D  8)

Title: Re: spine tester
Post by: Jake Allen on February 04, 2011, 03:32:13 pm

James Hill's way is slick as it can be.
I will be making one of those; likely next week!

Good link, thanks!

Title: Re: spine tester
Post by: artcher1 on February 04, 2011, 03:50:59 pm

I don't use the JH model any more Pat. That one is now outdated by the AB model now>:D................Art

Title: Re: spine tester
Post by: Pat B on February 04, 2011, 05:04:42 pm

Art, Is that a derivative of the Jim Hill version or something all together?

Title: Re: spine tester
Post by: jmack on February 04, 2011, 05:35:46 pm

People make spine calculation much harder than it needs to be. I have a 1x4 mounted on the wall with nails at 26" apart. Centerline is marked on the board with marker, and I then put a piece of masking tape over the centerline mark. Hang my arrow on the nails, draw a line from the top of the shaft on the tape, hang a 2lb weight from the shaft, and then mark the new position on the tape. I only use a 1/32nds ruler to measure the difference. 1/32 is accurate enough for me, and easy to see, but you could use a set of calipers if you need the .0001 or however close you need your tolerances... Anywho, spine is 26/deflection. So if the space between my two marks = 9/16ths, then 26/.5625 (.5625 is 9 divided by 16)=46.2lbs

If that is just too simple for you engineer types, then this is about as easy as it gets with mechanical(ish) action
http://www.youtube.com/watch?v=DhxYuzwDyVM

Title: Re: spine tester
Post by: artcher1 on February 04, 2011, 06:12:48 pm

Just a little something I cooked up Pat. Ain't purty, but works really well........Art

Title: Re: spine tester
Post by: stringstretcher on February 04, 2011, 06:24:17 pm

And Art's deflection matches mine exactly,,,so it has to be right ::) >:D ::) >:D

Title: Re: spine tester
Post by: wildman on February 04, 2011, 09:08:43 pm

Thanks guys I will have a spine tester before the weekend is out.

Title: Re: spine tester
Post by: Lombard on February 05, 2011, 10:47:37 am

Jmack, just checked out your video, and that is just about as simple as it can get. Simple yet fully functional.

I had built one similar to the one posted in the how to section of this site, but may trade it in for one of your design.
Here is the link to the buildalong posted here on PA, http://www.primitivearcher.com/smf/index.php/topic,4589.0.html

Title: Re: spine tester
Post by: Tom Leemans on February 08, 2011, 12:47:08 pm

Geez jmack! After building the fancy dial indicator type that I made, then seeing that video, I feel cheated out of several hours of my life, LOL!

Title: Re: spine tester
Post by: sailordad on February 09, 2011, 06:41:26 pm

i just watched that video
it damn sure done get any easier than that now does it
might just have to make me one of them

Title: Re: spine tester
Post by: bucksbuoy on February 10, 2011, 11:19:03 am

jmack- thats some awesome information. thanks for simplifying for us.

Title: Re: spine tester
Post by: Slow Tack on February 10, 2011, 06:12:18 pm

Yes, very easy to make and looks like it works very well.  Thanks for the info!

Title: Re: spine tester
Post by: Rick Wallace on February 11, 2011, 01:14:53 am

I made me one to!   ;D

(http://i1195.photobucket.com/albums/aa398/wall5834/PICT1297.jpg)

Title: Re: spine tester
Post by: Elktracker on February 14, 2011, 05:30:21 pm

I just made one of jmacks spine testers and after spineing some shaft I realized that the hooks are 26" apart then I cut my shafts down to 24 and added a 160 grain point,my spine is too stiff. How can I figure this out to where it works right? should I mount the hooks at 24" and re spine? And if I do this will I still devide my thousands by 26? or 24? hope this isnt to confusing. thanks

Title: Re: spine tester
Post by: stringstretcher on February 17, 2011, 01:25:04 pm

Elk.  When you spine you arrow at the 26" post spread, you are spineing the arrow at 28" for an AMO deflection.   The rule of thumb is to add 5lbs of spine for every inch you go out past 28" and substract 5lbs per inch for every inch under 28.  IE"  if you have an arrow that you spined at 60lbs on your 26" center post and cut that arrow to 24, you know have an 80 lbs spine arrow.  4inches at 5 lbs per inch is 20 lbs.  60 +20= 80.

Hope this helps

Title: Re: spine tester
Post by: Elktracker on February 17, 2011, 02:23:27 pm

Yes it helps allot thanks ;D