Checking Spine w/ Spine-O-Meter...?????

aromakr · April 24, 2008, 05:12:00 PM

Sorry guy's, I was just trying to answer some questions, didn't mean to give anyone a headache. I'll just keep quiet from now on!!!
Bob

snag · April 24, 2008, 06:27:00 PM

That's why I value this site...cause there are "people on here that have been doing this a lot longer than me"... Bob being one of them!

R. Combs · April 24, 2008, 06:57:00 PM

I agree snag, Bob has been doing this a long time and knows his stuff.

Rick

Van/TX · April 24, 2008, 08:04:00 PM

A good POC shaft will vary in spine very little regardless of orientation. However, I've never found that weighing against the grain was stiffer than weighing with the grain on average. After all the shaft is natural. You can't compare it to laminations of wood glued together which of course is much stiffer against the lams....Van

snag · April 24, 2008, 11:33:00 PM

I would have to respectfully disagree Van after going through several shafts and trying checking spine with the grain and against it. It varied as much as 10#. This is with one of the best pieces of equipment to check spine with and calibrating it each time. A board will warp with the grain but stand up to a heavier load on the edge against the grain...why? Because it is stronger and flexes less.

Bjorn · April 25, 2008, 10:22:00 AM

In my experience the amount of difference is not always the same, sometimes only a few#; but the stiff side has been against the grain. And I too will attest to the quality of the 'cupcake tester'.

snag · April 25, 2008, 12:53:00 PM

So that's what it's called Bjorn! lol Best spine tester money can buy. I have some of those old ACME POC shafts about made into arrows. I am going to recheck their spine before I fletch. I have been writing in black ink pen the poundage up by the fletching end so I can keep them in similar groups...real sign I have too many arrows? It is kind of nice when trying them in different bows though.

Cupcake · April 25, 2008, 11:02:00 PM

"Cupcake tester", eh. Not exactly my intent for a name when I designed it. I am very flattered that you gentlemen think so much of my design.

One of the biggest attractions for me in this sport is how much science can go into a simple stick and string. I have been setting up my garage and acquiring tools for bow making, so stay tuned, I think the fun is about to start.
Kevin

DesertDude · April 25, 2008, 11:21:00 PM

I can't wait to start bro..........

snag · April 26, 2008, 12:16:00 AM

Kevin, the other day I went out to an orchard they are cutting down to clear for housing. Cut a half dozen 7ft. staves out for bow making! I don't know what I am getting myself into, but I think I will like it!

snag · April 26, 2008, 12:35:00 PM

After putting 4 coats of finish on some POC shafts I have found that some have as much as 4# difference in spine weight if you rotate them from with grain to against grain. Seems like the coats of finish have narrowed the spine range...?

Cupcake · April 26, 2008, 02:10:00 PM

Snag,
Oh boy, more things to ponder. Don't think too hard about all of this because it will probably make you crazy. That is an interesting data point that finish makes them more uniform in spine. Is that consistent with all of them? It would be interesting to see if it happens for many dozens of shafts.

Bow staves now also. Don't get impatient and work them when too green.

This stuff is so much fun that who cares where it leads us. We will be off the streets and our wives will know what we are doing.
Cupcake

Bjorn · April 26, 2008, 02:15:00 PM

It is OK dear, I am off the street and hooking up with cupcake! LOL!

snag · April 26, 2008, 04:21:00 PM

LOLOLOL! Doesn't quite sound, right does it Bjorn?

The next batch of POC shafts I make arrows out of I am going to try and do the spine checking before and after applying a sealing finish more "scientifically". Got me wondering now!

I have dipped one extra time with some shafts to add weight...now I am wondering about spine.

DesertDude · April 26, 2008, 05:53:00 PM

Sometimes this Spine-O-Meter gives me fits!!! Like when you order 2dz 80-85 spine shafts, then you test them and they are from 70-75. Now I have to go through returning them...Frustrating.

snag · April 26, 2008, 06:32:00 PM

hmmmm...interesting Dude, I had thought I would go back through wood arrows I have made to check spine on them. It will be interesting if they fall within the range they were represented as.

Van/TX · April 27, 2008, 07:44:00 PM

snag, after you spine test more than "a few" check back. I've checked 100's of POC and found that against grain or with grain makes very little difference. Some spine more with grain and some spine more against grain. Do you zero the shaft after turning 90 degrees? Just a thought....Van

aromakr · April 27, 2008, 08:40:00 PM

Good Point Van, not only is it important to zero the tester after turning 90 degrees. But the biggest drawback to that type of tester is getting your eye level with the pointer. When you zero you have to move your head to see if its aligned properly with the mark, then when taking a reading you must again move your head to proper alignment to get accurate measurements.
Bob

snag · April 28, 2008, 10:07:00 AM

Van, yes I zero it and start at the same starting point. I get down even with the pointer and take my time to get every reading accurate...or why even do it!

DesertDude · April 28, 2008, 11:13:00 AM

The Spine-O-Meter is a great tester. This is the second time in 2 days I have herd something negitive about it. Depending on what level your looking at the needle at zero, you MAY be off 1# MAYBE. I hardly think that a 1# reading either way will effect anything since we get our shafts in 5# difference. I know for a fact that when we tested aluminium shafts it was spot on every time. Kevin has designed a tester you can test wood, carbon, and aluminium with the same tester. He uses the 26" span for woods and did the convertion for the other 2 types of shafts. Kevin is at the TOP of his class when it comes to this kind of stuff. Sorry for the Rant, sometimes things just rub a person wrong...