spine weight in rammin dowels

[tgr]

I've been making arrows with dowels (pretty rustic) and I continuously read about the importance of matching bow and spine weight.  I went down to a local archery store where they have a spine tester. (arrow with a weight).  Owner wasn't there.  Any idea on the correct way to use this?
My readings went from 70 to 30 depending on the position of the dowel.

Thanks ahead.. Tom R

[Pat B]

Tom, Place the nock end of the shaft on one upright, lay the dowel on the other and measure. Your other measurements are probably pretty good. You will find a great varience in spine weight with raw dowels.   Pat

[tgr]

Thanks Pat.  I guess I should be more specific.  I get those readings on the same dowel.  If I slide the dowel to the left or right I get a different reading. So I'm confused.  Is it the positioning of the dowel?  Also, the dowels are still 3ft long at this point.  TR

[Pat B]

When you check spine, the standard is for a 28" arrow with a 2# weight hung from the center of the shaft expanding a 26" span. The deflection in thousandths will equate to a given draw weight. With the shaft resting between the 2 uprights(26" apart) of the spine tester, and the nock at one upright measure in the middle, between the 2 uprights and see what the deflection is. That is your spine weight...for that side of the arrow. Imagine your shafts having 4 sides.      For each 1" over the 28" standard, subtract 5# of spine weight. For each 1" under 28", add 5# of spine weight
   With doweled shafts, the sides with the grain lines will be the stiff sides. With shoot shafts and cane arrows it isn't all that predictable. Cane is more predictable than shoot shafts because of the groove above the node where the side shoots form. With the dowels, on the side with the grain lines, one might be stiffer than the other. The stiff side is where your cock feather should go. So grain lines in and out and the grain feathering goes up and down. I hope I didn't confuse you too much. I think I confused my self, though!     Pat

[scattershot]

You need to zero the spine tester before each measurement, too.