Hi All,
Long time lurker but my first post. I am based in Oman and due to a gap in employment decided to try my hand at making bows... My first effort at a snakey self bow was successful ish, in that it did not break - but at about 15lb probably not surprising! My second attempt was a boo backed meranti r/d longbow. The choice of woods was based on what I had lying around the garden... Loved the way it uncoiled during the early pull, but alas the meranti was no match for the bamboo and it broke during early tillering...
After devouring the wealth of information on this site - my sincere thanks to those of you who give so freely of your hard learnt knowledge - I think I am better prepared to try again. My current bow is a bamboo backed desert hardwood. I harvested the hardwood many years ago for a different project, cut it into 30” slabs and it has been sitting for about 10 years drying out. I believe it is a type of acacia/mesquite. I have attached a photo of the grain and colour - can anyone ID the wood? It has an sg of about 0.8. Bamboo is an unknown variety from a garden centre, about 4" diameter before cutting. The bow was laid out in a pyramid style, is 58.5” ttt, 57” ntn, a shade under 1 1/4” width carried 3” past a 4” handle, then tapering to 7/16” tips. The belly lam was 12mm originally, with a 1/8” boo backing tapered to about 1/16” at the tips, The boo is trapped, but not, I think significantly. Including the built up handle it currently weighs about 14 ounce. One limb cracked near the tip on the belly during glue up when I attempted to induce some reflex. I skipped the reflex, glued the bow up as a flat stave and repaired the crack with West System 105, which seems to be holding up fine.
I am aiming for 35lb at 28”. I have it tillered to 32lb at 22”, looking for a circular tiller, but the bow is now developing set - about 1” so far. I have been attempting to follow the “no set tiller” instructions, although I admit to forgetting when and where to take measurements occasionally!
Looking at the tiller, I see both limbs bending more at the inner third near the fades, and I think that this is where the set is developing. So my question - to relieve the stress on the inner third of the limb should I increase the amount of trapping on the boo backing in that area or reduce the width through the handle, or...? I know that I need to tiller the outer third of the limbs more, but should I do that first and would that decrease the load on the inner limb? I am loath to put it back on the tiller tree in case I increase the set. I would like to keep the tips a little stiff.
The photos below show the current tiller at 22”. Apologies for the background, which makes it difficult to clearly see the tiller. I have also attached an early F/D curve. The numbers are a little sketchy due, I think, to using a very stretchy bow string i.e. as I slow down at each inch of pull to take poundage readings the readings float a little.
Many thanks in advance. I like the feel of this bow and would rather not lose it to the learning curve!
Mark in Muscat
