spine----again

[joachimM]

I would think that with an arrow longer than the draw length, the extra arrow length mostly acts as arrow head mass when shot.
Say a 32" arrow weighing 400 grains with a head of 125 gr, but drawn to only 26", then you have 5" of dead arrow weight at the tip plus the head. The dead arrow weight would then be 5/32 times 400 grains = 62 grains. So in my logic, that would be closer to shooting a 26" arrow with a mass of 338 grains plus a head of 207 grains (totaling 425 gr). The spine would have to be measured at 26" too.

Does that make sense?

[Pat B]

The longer arrow lightens the spine because it bends easier when shot. It also adds extra physical weight.

[Danzn Bar]

I would think that with an arrow longer than the draw length, the extra arrow length mostly acts as arrow head mass when shot.
Say a 32" arrow weighing 400 grains with a head of 125 gr, but drawn to only 26", then you have 5" of dead arrow weight at the tip plus the head. The dead arrow weight would then be 5/32 times 400 grains = 62 grains. So in my logic, that would be closer to shooting a 26" arrow with a mass of 338 grains plus a head of 207 grains (totaling 425 gr). The spine would have to be measured at 26" too.

Does that make sense?

Wow....my head hurts thinking about that....
DBar

[jeffp51]

Have you built a spine tester? I think mine cost about $17 all said and done. A digital caliper from Harbor Freight, a 3/8 wood dowel, a chunk of 2x4 a clamp, and a weight.

I did make a spine tester--also from a digital caliper and a 2 pound weight. I feel like it is accurate (or at least consistent enough) to start trying to make a matched set of arrows,  I just need to figure out where to start from.  If a self bow generally needs an additional 10# of spine reduction, then my longish arrows @60# may not be that far off.

[Danzn Bar]

The only way I can make a true matched set of cane arrows is to bare shaft test each one from the bow.  That takes some time and work.
DBar

[JackCrafty]

All these rules of thumb assume you have a bow that spits out arrows at 150 fps, minimum.  This also assumes 10 grains of arrow weight for every pound of draw weight when shooting.  This type of bow is common for the people who suggest the rules (because they also happen to make awesome bows) but is rare for the others.  A bow that's a rocket launcher can fire very stiff arrows.  Slower bows must shoot weaker-spined arrows.  How much weaker?  You just have to experiment.  These rules of thumb really only help to create a narrative.  The actual practice of making an effective arrow-bow matched set is not rocket science.  You already have "best shooters".  You've got all the info you need.  Go with that.  If the rules of thumb don't make sense, then there's something off.  Maybe many things are off.  Maybe it's different things for different arrows.  Maybe it's the weather today and everything will be different in a few weeks when it warms up.  Etc, etc, etc....
Normally, I don't weigh in on these conversations but I've had a couple of really frustrating bow failures trying to optimize everything for a batch of bows I'm trying to make for some friends.  Then I have to dry new arrow and bow wood and start over.  Sometimes the wood isn't dry.  Sometimes the wood is too dry.  Sometimes a matched set becomes unmatched mysteriously after a week of sitting idle.
 

Ok. I'm done venting.

[Danzn Bar]

Well said, All very good points IMHO  Mr. Jackcrafty...................guys, just make and shoot a bunch of arrows. 
Thanks,
DBar

[crooketarrow]

  I make all my bows center shot or as close as I can 1/8 at the most.

  That leaves a wide range of arrow spine. I threw my spiner away 15 years ago. Someone tells me there poundage and lenth. I rasp them to the size I need. Same way with arrow or tip weight I personally I have weigthed either your years. Dosn't matter to much at 12 yards.

   REMMBER WERE NOT COMPOUNDERS WERE 3 GRAINS MATTER.

  I totally with you JACK everything you've said is spot on.

[jeffp51]

Jack, That is good advice.  Thanks for your perspective.  What I am really looking for is consistency, and trying to figure out how best to get there.  There are so many factors.  I have no idea how fast my bows shoot, and I am not likely to find out--I would probably be horrified to find that I am only getting 120fps or something.  I would rather not know, I think.  They feel like they are shooting well.  But I want to make the best bow/arrow combination I can.  I am enjoying the process, so I guess that is the most important thing.

[Urufu_Shinjiro]

Yeah, I'm with Jack, I shoot a manchu style bow with a thumb ring, combine that with my gorilla arms and my draw length is somewhere in the neighborhood of 33", so I thought commercial arrows were right out and tried to make some bamboo stake arrows. Well I got really frustrated trying to straighten them, ever time I sat down it seemed like all I was doing was moving the bends up and down the shaft for a while, lol. I then discovered some really inexpensive 35" bamboo arrows, completed arrows, on ebay, for $50/doz. I can't make them for that cheap unless I'm literally harvesting shafts for free (and as above the time and frustration straightening them was costly in itself). They are not spine or weight matched by any stretch, but they're well made and bamboo is very forgiving on spine so I bought two dozen and out of those there's maybe 5-6 that are far enough out of spec to really affect my shots. Some are too thin/light and some are very stiff and heavy like shooting rebar but still fly straight as manchu bows like heavy arrows (I'm thinking when I start hunting I'll put blunts on these). As I draw them from my quiver I can feel if I have one of the out of spec ones and I adjust left or right accordingly and that works fine because even the out of spec ones don't fly terribly different. If I'm shooting a competition round of some sort I'll take those 5 or 6 light/heavy ones out of my quiver.

TL:DR version, with the right bow and the right shafts (bamboo for me) it's really not that big a deal as long as they shoot good.