My Improved Spine Tester

[Van/TX]

Very impressive!  You have done your homework        ...Van

[Van/TX]

"Easton Standard"  ???????
 

Agree with Falk.  Folks always trying to fix stuff that ain't broke....Van

[rbbhunt]

First class job on the spine tester

[Cupcake]

Thanks for all of the compliments on my spine tester.

I want to answer some questions that were asked.

For Ray - the software I used was AutoCad, a drafting design program.  Everything is simple triganometry.  I printed on a laser printer.

Falk and Van/Tx - I said Easton standard only because I was in a hurry.  I believe most arrow manufacturers use the American Society for Testing and Materials (ASTM) Standard - 28 inch support span, 29 inch arrow shaft and 880 grams (1.94 pounds) weight.  The deflection of the shaft is reported from this measurement.

The Archery Manufacturers and Merchants Organization (AMO) standard is 26 inch span and 2.0 pounds.  The AMO spine is then 26/deflection.

By the way, tha AMO has renamed itself the Archery Trade Association (ATA)

I have translated the spine measurements of Easton aluminum arrow shafts to the AMO spine by using beam deflection theory.  I have tested as many Easton shafts as I can get my hands on and have verified that my translation is correct.  I will hopefully be able to post this info when I get more time.

Kevin

[ArcticArcher]

Kevin,

Very impressive piece of equipment you put together!!

However, I do have a comment/question  

When has Trig EVER been SIMPLE?  :confused:    

[DesertDude]

Ok Kevin now your just showing off!!!!!  Kevin joined our group of stick bow shooters awile back. I thought he ws a bit strange at first till he told me what he did for a living,  yep you guessed it....."Rocket Sciencetist" or somthing very close to it.  This guy has some real talent.... Picked all our brains (what little we have) about Traditional Archery, he's like a mop. great job on the tester, and oh ya...I want one...... DesertDude

[Cutty47]

Forget the spine tester, when are you going to start taking bow orders? Lol...

[Cupcake]

Cutty,
Bows are on my list of things I want to try but I have this wild hair to perfect a spine tester first.  Then I need to start making wood arrows.

Desertdude has been a great friend and mentor in trad archery and I think I can lay part of the blame for my love of this sport on him.

Kevin

[Falk]

Cutty,
yes, I do bareshaft my woodies! And of course it works! Why not? And, if you think about it, it would make any spinetester unnescessary if we were not to lazy to do it for every shaft ... !
Your bow is a spine-tester after all! Better so: a tester for dynamic spine!

I don't argue about the "add 5# for FF, minus 10# for 2" of stringfollow" etc. thing! No! I agree totally here!
But that's not the point! AMO standard is also measured by deflection - only later translated into pounds - for convenience of the customer.

Don't read your spine in pounds and only thing you have to do is find yourself shafts with a deflection of, say .325" - or somewhere close to it. Done!
And it is of NO help to force new "standards" into existing fields. WHY change the old 26" 2lbs. standard? Now you have to know both! Now you have to look very carefully each time, as not to mix them and by which you order shafts etc. And make sure the pro shop owner also knows the problem. Big confusion!

     
Falk

[Aeronut]

Put me in line for one Kevin if you decide to manufacture.  I'll trade you a batch of wood shafts (probably have to be a big batch).

Good looking craftsmanship!

Dennis

[Cutty47]

Falk,

You're right.  Thanks for educating me on the fact that AMO standard was first measured in deflection, then translated into pounds.  I love the wealth of info on this site.

Personally, I haven't had the same luck bareshafting woodies as compared with carbons, or aluminums, and I know of quite a few archers, much more accomplished, and experienced than I who don't believe in bareshafting woodies-- Paul Brunner comes to mind.  

But I'm certainly not dismissing your personal experience, and if it works for you I'll bet you have a heck of a release.

[M60gunner]

Hey Kevin, have you given anymore thought to making the scale fold down for storage? I was real impressed with your whole project. Not only were to able to design the tester but you did a real great job crafting it.
See ya Sunday, Tom M.

[Cupcake]

Tom,
I worked on that a bit last night and it will be incorporated in the design in the future, not hard to do.
Til Sunday,
Kevin

[Big Dave]

 good looking spine tester