Monday, 25 August 2014

Heat Treating the Belly Billets

I glued up the belly billets and then clamped the spliced area in the vice while I pulled back the tips to feel the weight. I thought it felt quite stiff until I did the same test with a 36# bow. You can see they have some natural deflex/reflex shape.
That convinced me to heat treat the belly. The guy next door has been clearing out his garage and throwing tons of stuff into a skip, I salvaged an old Black and Decker Workmate and a nice length of hardwood which I trimmed up into two nice slats to clamp along

side the bow limbs to direct the heat along the limb.
The Workmate needs new handles, but it's V handy to have two when heat treating a bow, it's much easier to work my way along the limb.
I did it one limb at a time taking care to mask off the glued splice area with an off-cut scrap of so it wouldn't get any heat (see pic). I had the kitchen timer set to 4 minutes 30 seconds and ended up moving it along the limb in 10 bursts, that shows what a laborious slow process it is. 45 mins per limb, mind I made use of the time by giving the car a wash and tidying the garage. You can see I haven't gone mad, there is a slight colour change showing that the heat has actually done something. The big mistake with heat treating is to get it too hot, too close, too quick, all that does is char the outer surface. If it doesn't take about 30-45mins per limb, you aren't doing it right!

 The next step is to make a riser block for the grip area, I'll probably make it about 18" long tapered gently at the ends and with some curve so it will pull in a slight deflex as it's glued to the belly. I'll heat treat it just to get a nice colour match in the wood. Hopefully get that done today. All this work and washing the car has helped loosen my back, but it's still sore if I sit for too long. Not looking forward to the desk job tomorrow, I might take in the kitchen timer and set it to alarm every 15 minutes so I can get up and stretch regularly.

Update:- Got the riser and a thin 'Power lamination' glued on. The 'power lamination is just a thin lamination to help blend in from riser to main limb, it's more relevant in laminated bows, but I thought a bit of extra belly thickness wouldn't do any harm, it can always be rasped off, but it would be hard to add it in after the event.
It's clamped up with a hint of deflex (the riser section was shaped with a slight curve.
Pics tomorrow if it stops raining.

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