Primitive Archer

Main Discussion Area => Arrows => Topic started by: Slackbunny on March 24, 2012, 07:02:05 pm

Title: Spine Tester
Post by: Slackbunny on March 24, 2012, 07:02:05 pm

So I've got my framework all built for a spine tester, and I'm to the point where I just need to decide how to apply the weight and how to measure the deflection precisely. Any suggestions?

Title: Re: Spine Tester
Post by: Pat B on March 24, 2012, 07:04:20 pm

Google "James Hill Spine Tester".

Title: Re: Spine Tester
Post by: Prarie Bowyer on March 26, 2012, 01:40:34 am

I took a small glass jar and drilled a hole in the lid for a wire hook.  Went to the play ground and filled it up with play sand.  Used digital kitchen scales to weigh and removed sand till I was spot on.

Title: Re: Spine Tester
Post by: rmcpb on March 26, 2012, 08:30:41 pm

I made a simple spine tester out of some scrap wood and wire. Its surprisingly accurate as its a simple lever action where the short end of the lever is 2" and the long end 10" so if you want a .5" deflection the needle will point at 2.5". All I do is test arrows that work for me then use this to duplicate the spine in the arrows I make.

Its discussed on this thread in Ozbow  http://www.ozbow.net/phpBB3/viewtopic.php?f=34&t=12242 (http://www.ozbow.net/phpBB3/viewtopic.php?f=34&t=12242)

Title: Re: Spine Tester
Post by: Prarie Bowyer on March 27, 2012, 01:23:07 am

I should say i use a version of the "2jays" Spine testor.

Title: Re: Spine Tester
Post by: Slackbunny on March 28, 2012, 11:28:45 am

Okay, I think I have a plan worked out in my mind. I already have the supports set 26" apart with a central post that I can measure off of. I made a two pound weight with a mason jar filled with pennies and dimes, that I attached a hook to. I also have a set of vernier calipers with a digital display and tare setting that I can use to measure the deflection precisely. I'll try to post some pics this weekend when I get it all assembled.