Sunday, September 11, 2005

Splitting large logs

So you just got a big log of some nice wood that you want to turn into bowls.

Now what? It needs cutting down the middle for starters, and although it is possible to cut out a bowl blank nearly twice the diameter of a chainsaw bar, it is not a nice job nor without risk.

Two years ago I got a large maple log and was lucky enough to be able to get it cut right down the middle with a bandsaw mill. The resulting pieces were much easier to deal with than if I had had to do the splitting with the chainsaw. See the sidebar story here. Unfortunately I don't often have a sawmill handy, and many trees I get are from an urban environment and no sawyer will handle them because of the likelihood of nails being present.

A while back I was watching an archaeology program and they showed how long logs could be split with wooden wedges. I haven't had a chance to try it on a really big tree yet, but I did try a few smaller pieces and it worked quite well. The ends already had drying splits in them, so I started there. Otherwise I think a metal wedge, chisel or mason's bolster might be useful to get the job started.

The wedges I used were cut from scrap one inch maple. They were about 6" long and 3" wide, tapering from 1/8" to 7/8". They broke along the grain eventually, so another type of wood, maybe ash, might be more appropriate. I think I would also try making the 'sharp' end thinner so that it will start better in narrower cracks. Metal wedges would be preferable if available, but unless you plan on using them a lot, they are probably not an essential investment.

If the logs have been drying for any time at all there is probably a big enough radial crack in the end to get started with wooden wedges. Drive two wedges into the end grain both sides of the pith (assuming you are trying to split the log in half - I haven't tried anything other than splitting along a diameter). Then you should be able to get a wedge into the split that opens along the length. Open that up with a wedge on each side until the first wedges come free. Put those in further down the log. Keep working along the log in that manner until you have two pieces.

A book called Green Woodwork - Working with Wood the Natural Way, by Mike Abbott, has pictures and a description of splitting a log in there. He butts one end up to a rock, or other immovable object, and starts the split with a cleaving axe and maul.

He then opens the split with 'gluts' - wedges made from a 3 or 4 inch diameter branch. He recommends hard wood like hornbeam, beech or yew for making gluts.

Here are some other online resources on this topic:

Pat Rock blogs on Quest for a Plank from a Log -- Part1, and Part 2.

Over on Woodweb you can read how to do the job with black powder. Don't try this at home boys and girls.

Technorati Tags: , ,

No comments: