Do you always buy 8/4 lumber? Unless you want a massive knob on the end 6/4 should be more than thick enough lumber, with a lot less wasted material.
First my response was to this question:
Do you generally get your wood material from a lumber yard? Or what?
It was just a sugestion on where to look for wood. If Hickory logs were readily available to me, they would be my first choice. If thicker than 8/4 stock were avaiable, that would be my second choice. As far as 8/4 vs 6/4 "wasted material" question goes I think it is up to the individual to decide what will work best for them.
Cost comparison of blanks using the price sheet I posted. One board foot is one foot wide, one foot long, and one inch thick.
12" x 12" x 1" = 144" cu
Hickory @ $5/bf = $5/144" cu
Cost for blanks 3"w x 36"l:
8/4 board: 3" x 36" x 2" = 216" cu
216 x $5/144 = $7.50
6/4 board: 3" x 36" x 1.5" = 162" cu
162 x $5/144 = $5.63
$7.50 - 5.63 = $1.87
So 8/4 stock for a full size handle is about $1.87 more than 6/4. Probably a big deal for a manufacturer. As a hobbiest making a few handles, not much. But besides the pride in making your own, why make a handle at all? I suspect because of the poor quality so often expressed on this forum for mass produced handles.
Some thoughts on blank size, assuming you are starting with a 8-12 inch wide boards.
A 6/4 board is thick enough to make a handle. But how many "good" (grain runs the way you want it) handles are in that board?
An 8/4 board will allow a larger knob. More important to me is that the thicker stock will be easier for me to get the grain orientation for the handle I want. Both grain direction related to the axe head and grain runout. There is more wood to play with.
These are just my thoughts. How the two thicknesses net out I don't know.
Bob