Spine question

[BowEd]

DC, Art(artcher1) went all out with arrows. He understands arrows and arrow making like nobody else I know. Unfortunately his health isn't good and he hasn't been around for a few years now. Art scraped the whole cane shaft so they were the same stiffness all around.
Not only cane but hardwood shoot arrows also need for the stiff side against the bow. If possible, Art told me to put the second stiffest side to the shelf(down). That isn't always possible though.  Even doweled arrows have a stiffer side which is along one of the grain edge sides. With dowels you also have to consider the grain "flames" so if the arrow breaks when shot it doesn't drive the broken shaft into your bow arm.

DC......Now Pat B is explaining with edge grain or split timber shafts there is a rift[feathering out side]and an edge gran[straight lined side].You want the edge grain against the bow and the rift side on your knuckle side with the points pointing at you.In case the arrow does brake the points can't stab your hand.

[willie]

Aaron, that does make sense, all other things being equal, but as dc point out, a bit hard to determine beforehand. I suppose out of round would be a bigger factor as is the case with some of my bamboo.
My previous replies were not "bamboo specific", just generalities I guess.

It definitely matters. That's what's bothering me. I've got this arrow just about even now. It shoots a little nock left no matter which way I shoot it. Scraping the compression side of the strong bend is bringing it around

DC, I am having a bit of a difficulty understanding. Are you describing the left/right orientation of the way the arrow sticks in the target? How are the groupings  relative to your aiming point or the groups of fletched arrows?

[DC]

 the left/right orientation of the way the arrow sticks in the target. I can't really go by grouping. My"groups" usually take the whole face of the target. I can't count on any consistency.

[willie]

well, I should have not questioned you so much, your earlier description seems just fine. It's just that I was reading a bareshaft method that is more about group locations than knock orientations. 

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http://www.acsbows.com/bareshaftplaning.html
For a selfbow, I would find point on aiming to be more desirable than having perfectly straight nonfletched flight at extremely close range. That might just be something for the centershot/plunger button guys.

[Aaron H]

I would think that with bamboo, the difference in stiffness lies in the uneven wall thickness.
Maybe try an experiment on a particular shaft where there is drastic difference in stiffness from one side to the other, mark the stiff side, then cut the bamboo shaft in half lengthwise along that stiff side line. When you open it up, see if there is a noticeable difference in wall thickness from the stiff side to the weak side (possibly using a set of calipers). If there is a difference, I would then use that to determine which side to scrape. It would make sense to me that you would want to even out the wall thickness for consistency.
Does that make sense to anyone?

Once I split it in half it's a bit late to scrape I see your point though.

Haha, I guess I meant to use it to help you with the others

[DC]

Mostly what I was after was why do we reduce the compression side? I was sure that we would reduce the tension side.

But wait... Since we are dealing with one arrow the compression side for bending it one way is the tension side for bending it the other way. My head hurts, I gotta think this through

[willie]

Mostly what I was after was why do we reduce the compression side? I was sure that we would reduce the tension side.

But wait... Since we are dealing with one arrow the compression side for bending it one way is the tension side for bending it the other way. My head hurts, I gotta think this through

DC

you gave me second thoughts with your question, and said you were going to think this through, so I was just wondering which side?

and for wood arrows? the same?

[DC]

Thanks for bringing this up again Willie (I think ). I had put it out of my mind cause I finished the arrows I was working on and wasn't making any more. Now after my "stiff side" post it looks like I'll be rebuilding about half of my arrows so I'll have to think this through. I only use bamboo so I don't know about wood.

[Hawkdancer]

Things to garner from this thread!  1. Have a sip or 2 of your favorite beverage.  2. Check spine.  3.  Stiff side to the bow.  4. Scrape stiff side a bit to check spine.  4. Check spine.  5.  Sip beverage.
  6.  Scrap stiff side.  7. Check spine.  8. Sip beverage!  9.  If spine has gone below expectations, go to step 1.  Continue with step 1 and step 1., and step 1! . There ain't no arrow making emoji!
Actually, pretty good information - I'm on step 1!!!  I find working the stiff side tends to bring spine into line.  But you guys have broken more arrows than I have made or repaired!
Hawkdancer

[DC]

I think I'm going to go with Arron's suggestion. All I can think of is that boo is tension strong. If the wall is thicker on one side it would increase the compression strength the same amount as the thickness increase. Maybe when it's in tension it's already so strong that the thickness increase doesn't matter that much. It seems a little far fetched but if the boo is so strong that all or most of the bend comes from compression it starts to make sense. I think this is going to have something to do with a shifting neutral plane. I don't know how this would effect solid wood arrows or shoot arrows with a pith.