Woods response time to scraping

[Mo_coon-catcher]

Ever notice how some prices of wood seem to respond almost immediately after scraping while others seem to take a while to show? And needs more exercising to see what changes were made.

I just tillered out an osage molle that took a while to show that I scraped on it. I did my normal process where I scape what is needed, short draw a couple dozen times then short draw fire a few arrows. The wood would show almost no shift. So scrape again and reapeat until it looks good. Then all of a sudden it goes way weak. So repeat with the other limb to even them out. This one came out a bit under weight but made a pretty quick 45# instead of the 50-55 I was wanting.

Where as other times the wood seems to respond to the scraping before flexing the limbs. Think this is a difference between individual staves, between trees even within the same species, or a difference that's noticeable between species of wood?

I think it's mostly species related followed by the individual tree. The few times Ive worked osage it seems to show this slower response than the black locust that I normally work with.

Kyle

[RyanY]

I've had this happen a good number of times and I think it's definitely stave to stave. Seen it a good number of times in hickory. If it doesn't seem to respond to being exercised I'll leave it braced for an hour or so and come back to it. Slow and steady is key I think.

[Emmet]

Yes, I have a plum that's doing that to me. Iv' been scraping a few times and leaving strung, then shooting and re checking tiller. I been working at fine tuning it for a couple weeks now. I've taking it slow and still about 5# over what I would like.

[High-Desert]

I've had this happen a good number of times and I think it's definitely stave to stave. Seen it a good number of times in hickory. If it doesn't seem to respond to being exercised I'll leave it braced for an hour or so and come back to it. Slow and steady is key I think.

This is what I do as well, so far, it's worked for me

Eric

[Pappy]

Yes I have had that happen several times, Like Ryan said I think it is stave to stave for some reason. I just do the scrapes I think from experience it needs to get what I want and if it doesn't change much or any, them are the ones I will give a while at brace and short pulls before scrapping again.
 Pappy

[George Tsoukalas]

What Pappy said.
I used to have it happen.
Also, just take your time.
Scrape and exercise and short pulls.
Take your time.
Jawge

[DC]

I've always written that off to me forgetting how many scrapes I've made

[simson]

Exercise a lot!
I try to go as precise as posiible before I bend a bow / stave. So all my tillering with the scraper is a minimum of flakes ...
The worst what could happen is having an hinge at first bending. So wood cells crash at that first bend and all the following tillering suffers on this damaged areas. I believe the very first inches of tillering has the most effect on getting a bow in balance. The last inches are more easy to get proper.

[bradsmith2010]

great advice Simson,,

[Badger]

     One thing that will help to reduce that is pulling the bow to full target weight from the very beginning when it is still way too stiff. Get the limbs balanced out floor tillering and take it right to full target weight every pull. No surprises. Slight correction to that. Assuming the limbs are in balance. We never pull a bow further than what it takes to expose an area that needs work but once we get them looking good we go full weight.

    If we have to exercise the bow to register changes we are actually damaging the wood. We don't want the wood to have any memory of ever being bent if possible.

[aaron]

Great discussion! I have noticed this off and on while making bows and as an instructor. The methods of minimizing this effect have been covered above, but I still wonder about a couple of things:
1. Why does this happen? Can we predict which designs or methods or woods would be more prone to it?
2. What does this tell us about bow building? That is, does it perhaps serve as a warning that a bow is overbuilt, or that is is not in line with the mass principle?.

I sometimes teach a 4 day bow making class, and it becomes hard to get a student to do the required excercising/ bracing described above. This can lead to bows that change tiller after going home with the student.

[Badger]

  I think it is pretty simple actually, if you tiller a bow out to 35# and then gradually work it out to 50# and full draw you have no idea what you are dealing with. If you keep the bow at 50# from the start there are no surprises as long as you don't get any hinges and keep your tiller shape on. If the bow is underbuilt it will start showing set early on and you can reeevaluate your design or target draw weight before it goes too far.

[Gordon]

I second what Badger says.

[mikekeswick]

  I think it is pretty simple actually, if you tiller a bow out to 35# and then gradually work it out to 50# and full draw you have no idea what you are dealing with. If you keep the bow at 50# from the start there are no surprises as long as you don't get any hinges and keep your tiller shape on. If the bow is underbuilt it will start showing set early on and you can reeevaluate your design or target draw weight before it goes too far.

100%
I often see people not pulling to full weight quite late in tillering and I just don't get it.

[Pat B]

Exercise, exercise, exercise!
 You might also try sweating it by leaving it braced for an hour after each work session. However this is done only if the tiller is close.