From those of us that 'salvage' their wood I thought I would make a few posts on how I turn a tree trunk into a bowl. Although not technically difficult there are a few things you need to bear in mind. First of all there is no set way of doing this, so this is just my way. Besides being cheaper/free to 'salvage' your wood, the whole process can be enormously satisfying.
So this first post is simply about preparing that tree-trunk for the lathe. Yesterday I acquired a 2 foot piece of Alder that had come down in Storm Darrigh. The trunk was covered in Ivy, which happens a lot to the trees where I live. Alder is great to turn, but rots and Spalt's quite quickly. I retrieved the trunk section using my wheel barrow. The first thing to say about handling a trunk of this size (50-60Kg) is to be careful, Hernia's can be very painful, and I should know. You will also need a chainsaw, of some kind. If you've never used a chainsaw and lack confidence in using the tool, then seek help and assistance from somebody who knows what they are doing. Chainsaws, can be very unforgiving and it won't just be your little 'pinky' that you lose!
One of the first tasks after examining the trunk is to check either end for rot/inclusions/existing cracks.. Basically, you are aiming to cut the trunk length-ways through the centre of the Pith. Some people advocate removing a thin slab of the pith, due to the likelihood of radial cracks developing. I cut through the pith, knowing that I can turn the Pith out, once the piece is on the lathe. So as in the two photos above we will get two semi-circle slabs of wood. But before we make that first cut we need to check either end for cracks. On my piece of Alder I could see two incipient cracks, roughly traveling in the same direction. So I used a steel rule and sharpie to mark a line through the trunk linking both with a line 'scored' over the bark. This line would mark the direction of the Chainsaw cut. Ensuring, that the line through pith on either is placed in the vertical position, cut through the trunk, alternating at either ends trying to stay as close as possible to your vertical end line markers. Hopefully, you will end up with two semi-circular slabs, unlike me (see photo) .
The "Big Reveal" will indicate the condition of the wood. In my piece of Alder you can see a significant inclusion that can be easily avoided. My intention is to get a single simple bowl from either piece, but of course you could make smaller bowls if you wanted to. After marking out the bowl circumference, it's important to trim the piece as close as possible to the circumference line, in preparation to mount the piece on the lathe.
Which I will cover next...
