Stu's calculator and wood arrows

[Barclay]

When using Stu's Calculator to find a properly spined "generic" wood arrow, what should be entered for "Shaft Grains per Inch (GPI)" in Step 1 "Arrow Shaft Size"?

I'm not set on species (fir, POC, spruce, etc) yet.

Thanks!

[snag]

Depends on the shaft weight. I weigh my shafts and put them bundles. Then divide the grains by the length and you'll get the gpi.  If you don't have the shafts yet. I guess you'll have call whoever you thinking of buying them from and ask them what their shafts run in the spine range you are wanting to buy.

[Barclay]

Thank you, sir. I wasn't sure if that could be left blank and the software would select a "typical" weight.

For 160 grain points, I need a 2018 xx75 arrow as per Stu's Calculator for a dynamic spine of 57.7# (my longbow req's a 56.6# dynamic spined arrow).

I guess I just need to find what wood arrow would equal that 2018 XX75.

[SveinD]

Originally posted by Smallwood:
Here is what stu miller had to say, when I asked about wood arrows...
"First, go ahead and plug in the fixed variables that you know about the arrow.
Then select "wood shaft" from the arrow size drop down menu and also enter your nock weight (I use 13.5 for a Bohning Classic nock)
No comes the fun part! The two boxes below the "wood shaft" selection are the two variables you can play with, static spine and GPI. First figure out what type of wood shaft and GPI youwill be using.
I use 11.1 for Sitka Spruce, 12.2 for POC, and 13.5 for Douglas Fir as examples. It is best to measure your actual raw shaft weights as we all know wood varies a lot. From there just enter a static spine number until the dynamic output number for the arrow matches your bow's requirement."
hope this helps,
sammy

From this link..
 http://tradgang.com/cgi-bin/ultimatebb.cgi?ubb=reply;f=1;t=084902;replyto=000003

[Barclay]

Thanks very much!
  How's the weather in Norway tonight?

[Fletcher]

Yeah, enter 12 to 14 and you'll do fine.  You will gain about a grain per inch from a bare shaft to a stained and finished one.