arrow spine jig-grain direction

[stringnstik]

I built myself a wee spiner for checking arrows. basic design with a needle pointing to a scale type.

Question is I couldnt find anywhere where it specifies which way up the grain should be.
I measured some bare shafts and it does make a little difference if the grain is vertical or horizontal.
Im assuming it should be vertical(on the jig). The 2lb weight would mimic the arrow bending around the bow. The jig is horizontal while a shooting bow is vertical so we have to rotate the shaft 90 .

ie shooting the shaft normally ie upright we have the grain running horizontal same as cock feather. Thus the bow string is at right angles to the grain. So the shaft bends around the bow ie in the same plain as the grain/cock feather. So on our jig which bends the shaft downwards due to the gravity of the 2lb weight we should have the grain vertical yes?

[ichiban]

i think its grain horazontaly as if you cut self nocks thats how they sit (and how you should mount plastics) but i guess take both and average em out?

[Stickbow Hunter]

SS,

The following text with added diagram may help. The bottom example in the diagram is what your arrow shaft should look like when it is placed in your spining jig.

Jeff

"It is very important that you spine all shafts with the grain. That is, the grain lines on the ends of the shaft should be running vertical from the 12 o'clock to the 6 o'clock position. The rift in the shaft should be in the 9 o'clock and 3 o'clock positions.

The rift of the shaft that is facing you when the shaft is placed in the spine tester will be pointing to the intended point end of your finished arrow. If you are right handed have the rift pointing left, and if you are left handed have the rift pointing right. By doing this you are ensuring that you are testing the spine (amount of bend) of the arrow in the direction in which it is going to be bending around the side of your bow when shot."

Arrow article 8.jpg (36.01 KiB) Viewed 2765 times

[stringnstik]

exactly what I was after . I been looking everywhere for that bit of info
Thanks Jeff

[M.Hogan]

Does anyone know a site which has a spine jig build along???

[blu-dog]

http://www.jamesmhill.com/Spine_Tester.html

...hope this link may help!

[kerrille]

and the reason you keep the grain that way is if the arra splits when its being shot the broken shaft goes up and not in your arm or hand

...nev...

[stringnstik]

oo I so want to build Jims but having trouble finding a cheap deflection meter.
For now Im using this https://www.primitivearcher.com/smf/ind ... 5#msg63485one. which is made out of old bits n bobs.

I used a hacksaw blade as the pointer. just ground it down some.


another one I found on my travels
http://marshal.ansteorra.org/archery/fi ... tester.pdf

[Gringa Bows]

i did it the easy way,i just bought one of Forro's off this site.dont know if he still sells them though.......................Rod

[GrahameA]

Morning All

Rod did the easy solution and it does save a lot of mucking around. That sloution is avaliable in a range of costs and Keith's is about the lowest.

Consider this - If you are going to build one, just how accurate do you want to be? The more "accurate" you want to be the "better" you need to be able to read the deflection.

For many people a simple method of comparing one shaft to another will do the jobwhilst others will need (want) to measure the deflection to within +/- 0.0005" - and everything in between.

Just choose the machine that meets your needs.

[stringnstik]

Indeed Grahame
I was more interested in relative than absolute. I took "waterlogged"s idea and just made a much better pointer and dial indicator. For example the entire "reading edge" is in line with the pivot point. It reads the same angle all along the pointer not just the point.
I imported the dial into coreldraw and superimposed angular marks every 2 deg.which gives me a fairly good 1 deg resolution. I write down these deg on the shaft and use them for reference far more than the "converted spine".
The design does fall down around the 60deg mark and beyond. From the pivot point to the "nudge bar" is only 1" I have had shafts deflect more than this but they cant go any further, being supported by the nudge bar. I then have to go to 1lb weight and multiply.

Its very much a horses for courses. Im at the beginning of the learning curve :lol still getting a feel for it.

[GrahameA]

G'day

Its very much a horses for courses. Im at the beginning of the learning curve :lol still getting a feel for it.

My very first was a block of wood with a hole in it. This was nailed to the back of the workbench and acted as a cantilever support for arrows I then would use a known arrow and mark its deflection when I hung a Snapper Sinker off the end of the shaft. Then sort through the shafts to until I found enough that were close to it in deflection. Note: the cantilever does have a few advantages of its own. The next version consisted of replacing the drilled block with a block that had two nails in it - it was faster to load and unload.

The one I am using at the moment has a dial readout. The next will be a scale/pointer solution with a long pointer to enable easier reading. I have been considering a digital readout version using this which is not that hard to make.

The more sophisticated the design and the more accurate the desired result the longer it takes. Thus once you go down the more sophisticated road you need to have the radio/TV and DVD player/Coffee machine nearby so that you are comfortable whilst you spine a few shafts. There is nothing as exciting as spining a 100 or so shafts. Except perhaps spining several hundred.

Then again if you are spine matching - you need it in the workshop so you can sand them to alter the spine.

Actually what one really needs is a specialist "Arrow Workshop" preferably Air-Conditioned with a fume hood and exhaust system for varnishing and painting.

[stringnstik]

G'day

The one I am using at the moment has a dial readout. The next will be a scale/pointer solution with a long pointer to enable easier reading. I have been considering a digital readout version using this which is not that hard to make.

I have been thinking along those lines myself I like the plunger and readout idea. Waiting for one to turn up at work but alas so far nothing in the numerous odds n sodds draws about the place.

There is nothing as exciting as spining a 100 or so shafts. Except perhaps spining several hundred.

ha aah yes did 50 last night spine and weight and I could think of lots of other things todo

[kerrille]

mr stringstick if you are going to dunnolly i will bring you down a set of plans if you like i think there the same as forrows. i had it at lillydale if you can remember them . i know we had a lot of stuff beside the tent lol


...nev...

[stringnstik]

i do recall it, please do I will indeed be braving the winter solstice

[M.Hogan]

I found these plans...

http://peteward.com/2009pages/spinetester2.html

...I just dont understand, after you have made it, how do you know the spine of the arrow because the needle will just be pointing to a number???? do you have to calibrate it or somthing to a sharft that you already know the spine???