arrow spine tester construction question

[msamn]

Hi, I have been watching the very inspiring and beautiful arrow spine testers shown on this forum and had to try to build one myself. I used the James Hill method with the dial indicator and weight going directly on top. My question for those who know or those who have built an arrow spine tester is this. My dial indicator is spring loaded. and it takes about 4 ounces to depress it to 1/2 inch. While it won't affect precision, I think that it sure affect accuracy. Do builders of arrow spine testers take this into account?

[Rattus58]

Originally posted by msamn:
Hi, I have been watching the very inspiring and beautiful arrow spine testers shown on this forum and had to try to build one myself. I used the James Hill method with the dial indicator and weight going directly on top. My question for those who know or those who have built an arrow spine tester is this. My dial indicator is spring loaded. and it takes about 4 ounces to depress it to 1/2 inch. While it won't affect precision, I think that it sure affect accuracy. Do builders of arrow spine testers take this into account?

Interesting... Why did you decide to throw that additional piece of information into the mix..
       

I'm building either the same plan idea you have or that lever, which I have an engineer friend give me the formula for the lenght to give me the 2# over the shaft... but bein he was sorta in the suds when we talked, I wasn't clear on the endweight versus bolt etc... and the straight down one is simpler for me to visualize.

Much Aloha....  

[Pat B]

I prefer to have the weight pushing down on the center of the shaft instead of hanging a weight from an off center position...however Art Butner told me a way to compensate the hanging weight by doing it twice, once on either side of center but I don't remember his formula.
  I doubt the spring loaded dial indicator would have that much effect on the spining of the arrows. Lots of folks use this method with good results. You can compare an arrow with a known spine with one you have measured with the dial indicator and see how much difference there is between them.

[Art B]

I really doubt if there IS a standard for either the needle pointer or dial indicator Msamn. Or at least for most of us novice. I've  made both types and checked them and they both took an ounce of weight to depress their needles. Four ounces is a lot, is yours a Sears model? I tried theirs, and boy, was it had to depress. Took it back and bought a cheapo for 12 bucks.

If you're just making shafts for yourself and friends (and checking the spine of shafts where the spine is already known) it'll just be a matter of time until you get the depressed weight where you want it..........Art

[msamn]

Thank you all for your responses. Art B, I think you had the right thought, it really depends on the spring strength of your dial indicator, if it does not take much wt, then the difference will be small, But if like my cheapie $15 Turlen dial indicator it requires 4 ounces to depress, that might a difference in certain applications. Like trying to match an arrow you like but don't know the spine and you're trying to decide what spine to buy to closely match it. I determined that it takes 4 ounces to depress the dial to .500 without any arrow, and then measured a carbon arrow with a known .500 spine. it read .440 with the 2 pound wt and .500 with the added 4 ounces. A spine difference of 8 pounds.
For most of my ( and I suspect your purposes) the thing that matters most is closely matching spines within a group for consistent shooting. So the precision of this type of spine tester does more that you need.
just my two cents worth