Calling Bamboo Arrow Enthusiasts

[Pine]

I'm wanting to make some Bamboo arrows for my 35# bow.
I have made them for 45# and I used Bamboo that was 3/8" in diameter and the spine came out around 65# to 75#.
Any guess for what diameter would they me around 40# to 50# ?

[Pat B]

Sometimes with bamboo arrows you have to make them longer to decrease the spine. Also, generally because of the natural taper the spine range widens by up to 10# so cane arrows can be shot well from bows or different draw weights.
 My hill cane arrows(native bamboo) are 30" long, 3/8" at the point end and about 5/16" at the nock for my selfbows from 45# to about 60#. I draw 26"

[Pine]

Thanks, that's interesting.