The first attempt broke while being strung, maybe because I tried stringing it while it was still very warm from the back window. The second half of the log was successfully tillered at about half draw before putting the cordage backing on. I didn't go to full draw before adding the cordage back because I thought it might break. It now draws 24 pounds at 20 inches before the cordage is cinched up and 29 pounds at 20 inches after cinch-up. Often Native American bows were made from green wood, probably a holdover from the days when they had to use stone tools for bowmaking.
Greenwood is a lot softer than dry seasoned wood and consequently easier to cut with a stone tool.
I would also like to have had more heartwood on the belly of the bow but the tree just wasn't big enough. It was meant to be a stick bow anyway. The cord I used was yellow nylon chalk line, about .05 inches in diameter, three strand twisted. My choice was based on what I had at the time plus the fact that nylon has elastic properties similar to sinew. Other sizes or materials could be substituted.