Ozbow

So I thought it was time to diversify my bowmaking, and recurves have taken my fancy.

I've dabbled with steam bending, but recurving with kerfs and lams seems to be particularly appealing. So I had a go.

62" long, brown coloured ironbark with red coloured ironbark lams. I put two kerfs in each end, 10 and 11" long. The recurves themselves were modest: accounting for just 2" of tip displacement. I added a bamboo backing and while I was at it, put an extra 2 1/2 inches of tip displacement.

The initial stiffness was monumental. Most of the work I put into it was just trying to get it to bend enough to put the short string on.

Here it is just after getting the short strong on (a bit of correction needed):



Here it is pulling just under 40lb at 16":



Then: catastrophe.

This is one of the rare cases where bamboo fails. I can tell the bamboo failed because of the pattern of the fracture. The limb split lengthwise along the neutral plane, and the belly did not have any chryssals or frets. I suspect the bamboo failed in tension just past a node.







I immediately started another. On the current iteration I have only cut one kerf in each end, as I discovered that this is sufficient for a mild recurve. I have also decided to put just a tad more recurve. 3" of tip deflection.

We all break bows occasionally. It's immensely disappointing when it happens, but we must persevere and try again.

Bugga, better luck next time.

Looks good for a first effort Dave. I am sure you will iron out the bugs and get a shooter soon. That particular piece of bamboo was probably going to fail even on a straight laid bow. Keep up the good work mate.

Cheers... Rod

yeoman wrote:We all break bows occasionally. It's immensely disappointing when it happens, but we must persevere and try again.

Some more than others! I dread to think how many I break for those that work...

Good effort though. Looking forward to seeing the second attempt.

Hi Dave,

Although the bamboo may have been suspect the photos give the impression that there was far too much ironbark for the meagre strip of bamboo.
Running the bamboo full width and therefore gaining a higher crown may have helped the bow survive.

Daryl.

[I've lost count of the number of bows I have binned over the years.]

It's certainly a possible explanation. However I've made dozens of bows with a narrower bamboo backing than the stave, and with higher draw weights too. This one was only going to be c.45 lb at 28 in, and by this stage the wood underneath was fairly thin.

Nevertheless, my Mk.II is a slightly narrower stave, and the backing will indeed run the full width for the whole length. It's also just a tad longer.

I just need to make up some new forms to make the recurves over. This, now broken, attempt was done by bending the laminated tips around two chocks from bow shaving horses. Rudimentary and sufficient, but a bit inconvenient and with not as much scope for variation in future attempts as I'd like.

Bugger