Saturday, 21 November 2015

Progressing from 22" Draw

Doing some arithmetic based on 55# @ 22" gives an interpolated weight of about 75# at 28"
This gives me an idea of how much wood I need to remove. I've taken 10# off bows for people several times so I have a feel for it.
I'll go back through my E-mails and check on the target weight too.
Because the tiller is good I can pretty much rasp an even amount off along the belly and that will reduce the draw weight, but also help to bring the tips round a bit more. But I'll do it by degrees, it would be bonkers to try and take 20# off in one go.
1mm off near the middle where it's say 28mm thick will have less effect than 1mm off near the tip where it's only 18mm thick.
E.g. That works out as about 3.5% of the thickness at the grip, but 5.5% of the thickness at the tip. Not a vast difference but worth noting, especially as stiffness is proportional to the cube of the thickness.
Lets work out 28 cubed vs 27cubed and 18 cubed vs 17 cubed.
At the grip its 21952 vs 19683 so the stiffness has been reduced to about 90% of what it was.
At the tip its  5832 vs 4913 so the stiffness has been reduced to about 84% of what it was.

Anyhow, I know I need to rasp a good bit off the belly, checking that I'm doing it evenly along the bow and also checking each side, as it's easy to be rasping or spokeshaving at a slight angle which can make one edge thinner than the other.
I've had burst with the rasp and got back on the tiller, I've gained an inch of draw. I'll exercise it and than repeat the rasp and check on the tiller.
Here's the video showing what I did.

Latest:- 25" at 55# as of this evening.


  1. Really enjoying the videos Del.

  2. Thanks,
    I'm going to follow this one right through to the finished bow. It's something I've been meaning to do for ages. The Youtube videos are much better quality these days and actually seeing what someone does is so much better than trying to understand an explanation.
    When the movie comes out I'm thinking maybe Daniel Craig to play me? ;-)