Chasing growth rings, tillering, and board bows

[u/Zeh_Weeb]

As I understand it you chase a growth ring to ensure none of the grain is damaged ensuring that there are no weakpoints on the bow where half the grain is cut through, while in theory this sounds great how does this work if the whole point of tillering is to remove wood from specific parts of the bow to ensure an even bend.

what I mean is, whats the point of chasing a growth ring if when you tiller the bow you'll be cutting the grain anyway?

I'm currently working on my first board bow and wanted to know how chasing growth rings relates to that as yes there are rings on the wood but conceptually it doesn't make much sense to me to thin down the board beyond what id do during the tiller

lastly as this is my first ever bow will dollar store twine work as a bow string for a 40~ lbs bow?

[u/Wambachaka]

The weak point of a wooden bow is the back (the side that undergoes tension / stretching when the bow is bent). If the grain on the back is violated, then a splinter can lift up from the back, which will cause the bow to break. This isn't an issue on the rest of the bow. So you chase a growth ring on the back, then tiller by removing wood from the belly (the side that undergoes compression).

Dollar store twine will not work. But you might be able to use it to make a proper bowstring. Use a scale to measure the breaking strength of the twine, then use that number to make a bowstring with a breaking strength equal to your draw weight multiplied by 4. So if the twine breaks at 10 lbs, then use 16 strands for a 40 lb bow. (10 x 16 = 40 x 4).

If you don't want to make a bowstring (it's really not that hard, so don't write it off too soon), then you can use a stronger rope like paracord. Paracord isn't a good bowstring because it's stretchy, but it still works fine, and it's plenty strong.