Woods response time to scraping

[Mo_coon-catcher]

I'm glad I'm not the only one to notice this. I've had a couple staved act like this but not to the extent this stave has acted. This one also had some stress in the wood that would relieve as I removed wood as I shaped it out. I wonder if woods that have lots of internal stress like that are more prone to the delayed effect.
Next time I see it ill have to slow down and let the wood adjust to the scraping. This one was pulled to full weight early on at about 22". But I couldn't get the bend how I wanted it and kept tweaking and came out under weight before I was happy with it. I would get it so it looked good at brace again, excercise it for about 20 short pulls and a few short shots, it would look the same as I had just had it,  then start easing it back to the last known length at the weight I want. After that point I would notice that the limb I just scraped on went weak. Then repeat the process. I think I just need to slow down and give the wood more time to adjust to the adjustments.

Thanks for the advise everyone.
Kyle

[Springbuck]

That's funny, I have never noticed this, myself!   I will have to watch in the future.

I did learn the hard way, meaning it took me several "hard ways"before I learned, that you really need to exercise the limbs or whatever it takes to make those changes register before you go on.

Also, what Badger mentioned about always using, but not exceeding, the intended draw weight to flex the limbs, even if that means they only bend 2 inches, is one of the best sure-fire ways to hit both target draw weight and to hit good tiller.  No surprises in tiller, less set, and when the weight pulls the string to the draw length, you are automatically done.

Likewise, the Comstock method of using pencil, then rasp, then scraper for controlled, formulaic wood removal allows steady progress with intervals for thought and correction. 

Using these two methods increased my success rate greatly. Now if I don't destroy a stave while roughing it out or heat correcting, and the bugs don't find it if I put it aside for a few months, I almost always get a bow out of it.

[willie]

Springbuck

Haven't heard about (Paul) Comstock for a long time, and did a quick search for his method... 

Any links for those that have never heard of it?

thanks

Willie

[Springbuck]

Baker gives him credit for it in the TBB's, or it's part of one of his articles.  It's the thing where you use a rasp to lightly scuff up the whole limb during weight reduction, then scrape it until the rasp marks are all gone.  This way you know where you have not rasped because it is smooth, then you know where you have not scraped, because it is roughed up.  Each pass removes a pound or two of draw weight, and does so consistently and evenly.

I adapted the approach to other areas.  For instance, if I start with a roughed out stave, I often reduce it to perfectly even thickness all along the limb, say 3/4" or 5/8".  Then I know that to thickness taper the limb, I can mark from the tip in 2/3 of the length, rasp then scrape, then mark 1/3 of it, rasp and scrape, and predictably taper the limbs.  You have to take measures top avoid stair steps, but it's predictable.