A simple home made spine tester

[bjrogg]

While at Marshall I learned a lot about making arrows. Bill had a home made spine tester and I copied the basic principles of and made my own. It's made from scrap steel,a few nuts & bolts and a chunk of lead. I post some pictures then try to explain how it work

[bjrogg]

One thing I forgot to mention a cheap dial micrometer. I used a piece of 1" 1/4 square tube 28" long bored two 1/2" holes 26" apart on center. I stuck two 8" long 1/2" steel rods in the holes and weld them in place. I welded two 1/2" nuts on top of rods to make cradle arrow shaft. I cut the top 1/3 of nuts of and ground off shape edges. I used another piece of 1 1/4 square tube for a riser I welded this to back side of base right in center between the rods. I welded a short piece of 1 1/4" square tube horizontally to top but before I did I bored a 3/4" hole all the way through it close to the end. I then took a 3/4" bolt 8" long and 2 nuts put them on scale with a chunk of lead that I cut down till I had exactly 2 lbs. then I put bolt through 1/2" hole from bottom up put one nut on then chunk of lead then second nut. I also bored a 3/16" hole in bolt to put a safety pin in to hold bolt in up position. Next I mounted my micrometer. Mine had a tab that stuck out the back with a hole through it. I weld a nut on riser so that micrometer tip would be slightly above where bottom of arrow shaft would set. The I ground the corners off a mother nut so it could turn without hitting risers and turned it on a bolt then put bolt through micrometer mounting flange. I welded a short bolt on end for a lever handle.

[bjrogg]

To use it you simply put shaft in cradle loosen micrometer mount and adjust tilt of it till it is centered on bottom of arrow shaft then tighten. Next turn micrometer on and zero it. Then remove safety pin from 3/4" bolt and gently lower wieght on shaft. Read micrometer. You can find graphs online but I just take the distance between post 26" and divide it by the deflection this equals lbs of spine of shaft.
Example.   26" divided by .5" deflection equals 52 lbs spine   Hope I explained all that good enough Bills was made from wood but for me metal was simpler
Bjrogg

[Pat B]

Nice tester. Mine is the same principal but made of wood.

[bjrogg]

Thanks Pat I was pretty tired when I posted it last night could hardly stay awake to proof read it. Hope people can understand my long drawn out explanation. Got a few mistakes but I think they should be able to figure them out. It works good can't think of anything I'd change
Bjrogg

[Pat B]

One thing I did on mine was to make one of the uprights adjustable for cane and irregular shoot shafts. I have it so it moves back and forth using a wing nut to tighten it in place.

[bjrogg]

Mine is adjustable to I maybe didn't explain that good enough. The tip of micrometer sticks up above where straight shaft would cross. Then I can loosen 3/8" bolt that mounts micrometer and tilt tip slightly in or out to get it right on center crown of shaft. Then I just zero micrometer and it's ready to use. It's a lot simpler to show how it works than explain it

[Knoll]

It's a lot simpler to show how it works than explain it

Ain't it the truth!  Ya did explanation well. Thanks!

[Lumberman]

Very simple but more accurate than mine, I like it! May need to build myself one from wood

[Danzn Bar]

Brian,
Really like the way you can adjust the micrometer to the shaft diameter...that's a very nice spine tester....I don't have a welder that's why I made mine of wood.
Again real good job....
DBar

[bjrogg]

Thanks for showing me yours Bill I really like it and it only took about an hour to make. Wouldn't have thought how to do it with out seeing yours.
Bjrogg

[Traxx]

While a very nice spine tester,i would call it anything but simple.
Now simple,is my old tester,before i traded for an Ace.It was 2 nails in the wall,with the defection lines drawn on with a sharpie.

[bjrogg]

I guess I'm going to stick with simple Traxx. I maybe should've added accurate simple but I think it's both. Pat and Bill both made theirs from wood if that would help or you could mount micrometer on wall between two nails. The principle is simple for me the build was to only took about an hour. I don't think most guys here would have much trouble making one if they saw it. Afraid my explanation was the most complicated part.
PS some of the measurements I stated were just from memory and not correct I wasn't buy tester when I wrote post. The post are 26" apart but mine are 13" tall. It's not critical but leave enough room to mount your micrometer.
Bjrogg