Saturday, March 25, 2006

Cutting large pieces of wood

I have had a couple of large pieces of wood outside the workshop for several months waiting for me to get them cut up and roughed out into bowl blanks. I made a start on them a few days ago, and I thought I would share some pictures with you.

This first piece is a crotch of yellow birch and I want to take a slab out of the middle to remove the pith, leaving two big bowl blanks on either side. In this first photograph you can see how I have marked cut lines all the way around the log. My chainsaw is not large enough to cut all the way through in one go, so it will need to be attacked from all sides. Careful marking and cutting is important so that the saw cuts are all in the same plane. So here I have the log on a flat surface and have a used a piece of card cut to the desired width to ensure accurate marking out.

Notice that I have trimmed a little bark off both sides. This makes it easy to mark the lines, and also makes it easy to stand the log on its side for cutting as you can see in the next picture. Here
I start by carefully cutting a shallow groove all the way around the marked lines. This not only makes them more visible, but will also make it easier to control the saw when the main cutting starts.

The hardest part of cutting these grooves are the cuts across the endgrain. Chainsaws aren't designed to cut endgrain, and the end of the bar tends to wander sideways if it is not kept in a groove. So I cut the grooves along the sidegrain first, then used that to anchor the bar while I let the power unit down to extend the cut across the endgrain. Working this way makes the line difficult to see, so I stopped frequently to check that I was following the line accurately.

Once the grooves are cut all the way around, work can begin making deeper cuts into the wood. Start at the corners, making diagonal cuts and ensure that the bar stays in the grooves on both faces. Work all the way around cutting deeper and deeper. Take care when the nose of the bar gets into the wood; this is the danger area for getting a kickback.

I worked on both cuts at the same time to keep the piece balanced and stable for as long as possible. Once one side was removed, the remainder had to be balanced against a bench leg to keep it upright. Here are the three pieces finally seperated.

Even with all the care I took, some of the cuts wandered off a little bit. Even so, this was much more accurate than if I had tried to eyeball it.

Here is one of the pieces off the side, trimmed up and ready to be turned. Spending a few minutes with the chainsaw can save a lot of turning time with these large unbalanced pieces of wood.

Finally here is the central slab after it has been cut on the bandsaw. This piece had the piths running through it and this needed to be removed. The round piece is destined to become a small bowl and was located to avoid the pith. You can see some of the nice crotch figure in that piece. The two large pieces down the sides could be used for either small bowls or for weedpots. They will be dried first, so I don't have to make a decision yet as to what they will be used for. the two smaller pieces have remnants of pith in them, so they are likely to split. I haven't decided yet what to do with them, but they will probably be cut up even smaller and prepared for bottle stoppers or inlays.

If you take on a project like this, do take care with the chainsaw. If you are unsure if what you plan to do is safe, get some help.

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