Sawing Posts and Beams

How do you get good structural timbers from a log? August 26, 2008

Question
I am new here and have just spent the last two hours poring over this site as there is tons of useful info. I was wondering if you can cut more than one beam out of one log, and be reasonably safe from twist. I’m really new at this and any help is truly appreciated.

Forum Responses
(Sawing and Drying Forum)
From contributor J:
Welcome, glad you found the site information. I have a couple of questions. What type of wood are you cutting? How big are the beams? Also, what are you using to cut them?

I might be mistaken but are you asking if you box the heart so one log equals one beam? I would reckon it would depend on the above mentioned items. I have cut posts out of one large log. It was Monterey pine, and they didn’t twist. I got about six 6x8's out of the heart wood, no sap wood. What are the posts for?

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From contributor A:
I'm sort of new here as well so my question to you may seem odd but I've always thought that the heart wood was desirable, but I think after reading many posts I've noticed that the heart wood in fact is not the desirable part of the tree?

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From Gene Wengert, forum technical advisor:
In most cases, the heartwood is the most desirable part of the tree, but with maple the white sapwood is most desirable and the brown heartwood is mostly trash. The heartwood of some species has decay and insect resistance, making heartwood desirable. Sapwood is almost always white while the heartwood has color.

Twist depends on the tree itself (is there spiral grain) or whether the beam is sawn parallel to the pith. If sawn parallel to the bark, twist is more likely. Many logs will yield multiple excellent beams.

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From contributor B:
You can't go wrong getting posts out of aromatic cedar, if you have some big enough. I've sawn plenty of 6"x6"x16' long cedar and never had one twist yet. You can also set them in the ground and they will last a good while.

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From contributor D:
I think that posts can be boxed heart, while beams are best when free-of-heart-center (FOHC).

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From contributor A:
If a timber is Free of Heart (FOH) or more than one per log it means that it was cut away from the center of the tree. As a rule I will not cut one unless it is six inches away from the center. If I cannot make a 12x12 from it and cut my other timbers off the sides of that then it is just one timber per log. Posts are best if the heart of the log is centered in them. Timbers sawn parallel to the center are better.

If you have heartwood and sapwood in the same timber (more then 1/4 thickness across the face of the timber) you will find the timber will bend the ends toward the center of the log (heartwood side).

Q-sawn beams will bow the same way but can be useful in they will flatten back out under live load if used for floor joist. The size of the timbers and logs will tell the tale but for logs under 20 inches just one post per log. Also I try not to use the bottom 8 feet of a tree in a timber.