Saturday, 31 July 2010

Marking out and Retail Therapy

I tried to find the best line for the bow by stretching a string along the stave, you can see there is some twist in the stave and it's profile isn't a perfect semicircle.
After much fiddling and re-drawing I finally sketched out a rough shape for the bow.

Now I had planned on doing all the work by hand but that Ash is damn hard and my axe very heavy, not to mention my tennis elbow. I spent a bit of time sharpening the axe which helped a bit.
When you can sharpen your pencil easilly with your axe, then you know it's sharp.
Anyhow I succumbed and roughed out the basic shape with the band saw, (having flattened the belly a bit with my axe first to make it sit better on the bandsaw table).
There is still plenty of thickness to remove and it's all axe now (the drawknife didn't like it at all. It makes me appreciate how nice Yew is to work).
So, that's where the retail therapy comes in, I ordered a new axe, a Bahco one made in Sweden, so the steel should be good. It's 0.75kg rather than my current 1kg one, it has a wooden handle. There were some real cheap ones and some with steel handles and rubber grips but that just didn't seem right to me. Anyhow, I'll let you know what it's like once I've tried it.
The bow lets you know when to stop using the axe as the limbs begin to flex and bounce the axe head.

My bandsaw blade is also shot to hell (they say that a decent quality blade makes all the difference) so I ordered a couple of good 3tpi blades with extra set on the teeth for ripping along logs. The internet is great, you can spend money on specialist stuff without leaving the comfort of your own home.
The pics don't need further commentary, except to say, the stave hardly even flexes yet (it thinks it's a roof joist or somesuch!)

When I'm using the axe on the belly of the bow I find it cuts best attacking the edges rather than straight onto the broad flat face, the sketch shows how I'd work down one edge (1) then edge (2) and finally the face (3) as I work down towards the dotted line.

I don't know if this is 'good' technique, I just find it works for me and allows a good amount of timber to be removed when roughing out. It also allows finer control of the axe as you take cuts 1 & 2 close to the dotted line.

The sketch represents a cross section about 1/3 of the way down a limb, as per pic on the left.

You can see the remains of cuts 1 & 2 and the remains of the pith core of the log.
There are a pair of knots visible half way down the limb, they are running sideways out of the stave and will probably dissappear as I work the belly down. The axe can tear out nasty divots around knots so I'll need to work carefully, near there and start using a rasp, or spokeshave.

Any de-crowning, as discussed in the previous post will be done later once the stave is begining to flex, it may not be necessary with a bit of luck.
It would be nice to keep the smooth untouched back, but I do expect I'll need to shave off a tad.

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