# Spine-O-Matic....Home made Spine Tester



## OBE (Dec 4, 2009)

Great job! Good luck to you with job hunting.


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## 138104 (May 14, 2009)

That is awesome! Good luck with your job search. I'm in the same boat as you!


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## rob-c (Mar 9, 2010)

where did you get the scale?


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## 2_Smithereenz (Feb 1, 2010)

rob-c said:


> where did you get the scale?


Follow that link I posted to the directions and it's included with all the info. You can print the picture of the dial scale by itself and enlarge it. I set my printer to 125% because that was as large as I could get it and still have it all on the same sheet of paper. Those little hash marks in between the bigger lines are real hard to see unless you enlarge it, and then they are still a little hard to see.

Here's the link again in case you may have missed it.
http://marshal.ansteorra.org/archery/files/aob2003/spinetester.pdf


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## Lane Puckett (Feb 21, 2005)

Chris,
Very nice work.

Remember that when you enlarge the scale on the printer you have to change the pointer length and pivot length so it scales correctly.

An easy way in my mind to check your scale is zero your pointer on a solid unmovable shaft. Then take a shim of a known thickness, say 0.400, and insert it between the shaft and the pointer. Your deflection should match the scale. I hope that made sense.

Measure your shim with a micrometer if you have one available.

If not let me know and I'll make you a few shims of exact size and send them out to you.

This assumes you want it calibrated. In reality it doesn't need to be calibrated if all you are doing is using it for your own use and keep good notes on what deflection works for each of your bows. Repeatable measurements is the key.

That was an old standard (26") shown in the plans. Folks will correct me if I'm wrong but the current AMO standard is now 28". I read that somewhere.
yep here it is
http://www.archerytalk.com/vb/showthread.php?t=1164528

Lane


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## 2_Smithereenz (Feb 1, 2010)

Thanks Lane. 
I checked the plans again and it said that no matter what the size of the scale was printed out at, as long as you keep the 2" dimension from the pivot point to the end that rides the bottom of the arrow shaft, that it would come out right? I'm just hoping that's right.
I used my calipers to get that dimension dead on.

I tested some of my arrows with a known spine on it and they were right on the money. Hopefully I got lucky with it?

Like you said though, consistency is the key and as long as I know what numbers on the scale coincide with my own outfits, then I guess it's serving it's purpose? I always keep notes on stuff anyway, I learned that from my reloading and I write down every little detail.

That shim idea is a good one. I'm going to go out and check that right now, there's no reason why that wouldn't work. I'll report back here and let you all know how it goes.


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## Lane Puckett (Feb 21, 2005)

MAKING THE DIAL
1. Photo-copy the dial illustration. Most commercial photo-copy machines have an enlargement feature. Enlarging/reducing does not normally affect the accuracy of this dial in any appreciable way if you keep the short spoke equal to "Line A". However, I find letting "Line A" equal 2" to work best for me.


What this means is print it out and make your pivot to arrow shaft length the same distance as the 'A' line. If you scaled the 'A' line to equal 2 inches then yep you are good to go.

I suspect we are both saying the same thing.


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## bearauto11 (Apr 7, 2010)

Here's my take on enlarging the scale. Because it is an arc, when the pointer moves, the end of the pointer will move more, but the pointer will also move the same number of degrees. When you enlarged it, you basically made the circumference of the arc bigger. So, the numbers should all be the same degrees apart, they just are further out on the arc of the circle and it shouldn't matter if you enlarge it. 
That would be my theory. However, now that I reread what I wrote, I'm not even sure I understand what I'm talking about.
I'm planning to make one just like it. Thanks for bringing it to my attention.
--Tom


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## bearauto11 (Apr 7, 2010)

I'm sorry to disagree (especially if I'm wrong) but, I don't think you want to scale the small end of the pointer. I think it needs to stay that exact two inches. If you make the short end of the pointer longer, it will decrease the distance the pointer has it has to travel to get to the distance down. But the arc where the long end of the pointer goes will increase the distance between lines as you increase the size of the arc, but it should still be an arc with the same center point and the same number of degrees between marks. I was just playing with it with a pencil and paper and it seems to make sense. 
Good Luck,
--Tom


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## 2_Smithereenz (Feb 1, 2010)

Lane Puckett said:


> MAKING THE DIAL
> 1. Photo-copy the dial illustration. Most commercial photo-copy machines have an enlargement feature. Enlarging/reducing does not normally affect the accuracy of this dial in any appreciable way if you keep the short spoke equal to "Line A". However, I find letting "Line A" equal 2" to work best for me.
> 
> 
> ...


Ah ha! Now I see what your getting at, I read it differently. The end of my pointer below the pivot point is 2" but I couldn't enlarge the scale big enough to make it reach 2" on line A without it getting too big for the paper. That's where the difference will be.........I gotcha now. 
When I enlarged the scale trying to get it up to the 2" dimension on line A half the scale was off the paper, so I just stuck with the size that all fit on the paper. My line A is actually slightly over 1.750" so that's the length that the short end of my pivot needs to be, then it should be nearly dead on accurate. 
You were right, I was misunderstanding the directions. It's all relative to the size of line A, no matter if you print the scale a foot wide, or 6 inches wide as long as the pivot point length is the same as whatever the length of line A is because line A length will change with enlargement of the scale size.

I got it now. 
Even though it's off just a bit, I checked it with a popsicle stick which measures exactly .100 and the movement on my scale was about .073 so I'm off by .027" in deflection.....which translates into about 5 lbs. when I get up around the 60-70lb. range. 
I'm going to have to shorten my stick about 1/4" to get it right on. I'll work on that tomorrow, I'm tired now. 

I'll report back here tomorrow when I get it fixed.


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## 2_Smithereenz (Feb 1, 2010)

*Update!!*

The problem has been remedied. The confusion was pertaining to "Line A" and I misunderstood the instructions, I thought that the pivot point to the short end of the pointer was to remain a constant 2" no matter what size I enlarged the dial face to.......*that was wrong!*

When you print this dial face and enlarge it to 125% like I did, measure "Line A" and use that dimension as the short end, by measuring the distance between your pivot point hole and the end of the pointer where your wire is that contacts the bottom of the shaft. That distance must always equal "Line A" no matter what size the dial face is.

My line A was exactly 1.750" so I had to cut 1/4" off the end, I did the repair late last night and glued it all back up so it would be dry this morning. 
I put it all back together and tested with my 2117 Aluminum Easton shaft with a known spine value of .400 and the dial is now *Dead Nutz!!*

I put my shaft on there, zeroed it in, then hung my weight and the needle went to .400 on the dial face exactly. 

I hope anybody who is thinking about building one of these reads this last post about the dial face confusion I ran into before they screw up their pointer like I did. No big deal, just a minor set back.


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## Lane Puckett (Feb 21, 2005)

Chris,
Not to confuse this even more but some printing programs will 'print to page' and by doing so the program changes the printed X axis vs. Y axis.

I try not to get hung up on the actual spine number.

What I want is all my arrows to spine the exact same or as close as I can get.

The reason many went to the dial indicator for spine testers was to tighten up some of the +/- tolerance on these style testers. This designer indicated that it was accurate to within 20 thousands. Pretty good for what we probably need. 

Dial indicator testors have other issues they add that this style doesn't suffer from.

The big deal is just to get a repeatable tester from arrow to arrow. You now have that. Also if you are careful in reading the pointer right (use the edge of it) you should be able to get arrows to +/- about 5 or 10 thou.

Read the article from Primitive archer I sent you on matching wood shafts. Now you have an entire winters worth of work making a couple dozen arrows. But they will be better arrows than any amount of money could ever buy.


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## 2_Smithereenz (Feb 1, 2010)

Oh yes, definitely. That was the intention of building this spine tester was for the traditional arrows, and whether it's 100% accurate for all other shafts or not it will work awesome for my wood arrow building. Like you said, I've got a way to guage my results, keep notes, and repeat what works and that's all I was hoping for. Now it's accomplished with a solid degree of accuracy based on what I measured this morning with the Easton 2117 it's now right on the money. :wink:

Speaking of articles, I just printed all those out and I'm going through them right now. There's some great material in these pages and I've got a lot of learning ahead of me. 

Thanks again Lane, much appreciated!


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## bearauto11 (Apr 7, 2010)

Well, I guess my theories were all wrong as it turns out. Sorry about that I guess I was more confused than I thought I was. 
Let me ask you a question about your spine tester though.
You inspired me to make one also and I used the scaled version of "Line A" like I think was the verdict that needed to happen. 
It seems to be working OK, but I am trying to confirm spine with some Easton aluminum arrows and they are spining out stiff (less deflection then their charts say). Now, I think I know that Easton spines their arrows at a 28" span with a 1.98 pound weight. Should the .02 pounds make up for the 2" span difference or should the arrows be spining out with less deflection than says in the Easton charts?
Thanks for the help and the inspiration,
--Tom


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## Lane Puckett (Feb 21, 2005)

Tom,
No the 0.02 pounds won't make up for the 2 inch difference. You could make an adapter to lengthen the pivot points an inch on each side. Use the adapter when you want a 28 inch spine measurement and pull it off for 26 inch.

Or you could take known spine Aluminums and make a cheat sheet to adjust the readout.

The most important is a repeatable consistent measurement.

Lane


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## bearauto11 (Apr 7, 2010)

Thanks Lane,
It does seem to be consistent and the wooden arrows seem to be coming out alright. So, I'll just assume it's working perfectly.
Thanks again,
--Tom


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## jlnel (Dec 22, 2009)

nice job!


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## WillAdams (Jun 6, 2009)

I wrote a computer program for drawing up dial faces:

http://www.artofproblemsolving.com/Forum/viewtopic.php?f=519&t=367100

All you have to do is indicate what size the lever is, and what size you want the dial to be. I'll have to see if I can get it running on a server so that people can enter the values in a form, then get a .pdf --- in the meanwhile, send me a private message w/ the length of the pivot end of your pointer and what size you want the dial to be and an e-mail address and I'll send you a customized .pdf.

William


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