Ozbow

Hi Guys, well the title says it all really. They say if you aren't breaking them you aren't making them, and in a funny way I was getting a little nervous that I was making my fifth bow and they had all survived so far. Well, I can relax now!

I'm not to upset though, as I learned an absolute ton making this one, and am excited about applying what I know to make some real shooters from this point.

This was my first attempt at a pyramid bow, and now i know a 50lb bow can easily come from 30" long, 1 7/8" wide limbs, tapering down to 3/8" tips. My next bow is definitely going to be another pyramid bow .

This was also my first attempt at heat tempering the limbs into reflex prior to backing and tillering. It's a bit time consuming, but I can't see myself not doing this to every other (hickory at least) bow I make. I lightly toasted the limbs with a heat gun while in 4" of reflex. After the bow had cooled and was removed from the form it sprung back down to 2" of reflex. After tillering and about 60 arrows, reflex seemed to have levelled out at 1". The heat treating really seems to turn a hickory bow into a different creature- the induced compression resistance makes the limbs really 'springy'. Even when unstringing the bow I could feel it wanting to 'snap' back to it's reflexed resting profile.

But yes, it broke. I failed to notice a small knot on the back of the bow, and had began tillering without having applied the linen I had chosen to back this bow with. I was worried I'd remove the tempered layer of belly wood whilst tillering and have to re -temper it. I didn't fancy trying this with the backing in place, so at 15" inches of draw I heard the 'crack' and found the offending knot, with a crack spreading in either direction, across the limb. At this point I decided to learn a little bit about the properties of linen, and applied firstly a 3" patch over the cracked section of limb, then the full length piece along the full bow length with TBIII.

Well, I now know that linen is pretty impressive stuff. It held the cracked limb for long enough to allow the bow to be tillered out to 28" of draw @50lb, and then shoot a few dozen arrows markedly quicker than any of my other self made bows have done before. I'm trying to be objective here (which is a bit hard) but I'd say this bow was only marginally slower than my Joe Vardon glass laminate longbow. But yep- then it cracked. not explosively, but enough for me to see that the damaged and patched section of limb had finally failed.

So although bummed, I'm a bit more knowledgable now that I was before, and am absolutely busting to get my next hickory stave and make my next bow. Pyramid bows-tick. Heat tempering-tick. Linen backing-tick! Not a bad result.

That's a nice looking bow mate, its a shame it cracked.

But every little failure is a lesson in itself and if you listen to the little lessons you can improve your skills rapidly.

I would be tempted to get the linen backing on before you start tillering the bow as it will provide the last fibre layer for the maximum bending stress to accumulate within thus its not in the timber.

Your definitely right about it being good stuff tho. I just made and broke a bow at 130lbs with a linen backing which was all that was holding it together in the end. Pulled very large splinters underneath the linen but it didn't fail catastrophically.

Stick at it and I look forward to seeing the next one!

Colin.

Selfbows are always a challenge and no matter what the outcome useful lessons can be learnt.

Over the years I have probably binned over twenty bows.

I must take some photos of a spectacular limb failure that happened during an experiment and post them.

Daryl.