Timber Framers Guild Forums General Discussion Forestry Topics Picking Trees

Hello Gentleman,

If we could stay on topic please.

Ken, I certainly appreciate your gesture and I might take you up on it if we still lived on Pangea.

I am trying to find you all thoughts on picking trees for timbers.
What I mean by this, regardless of species, is dimensional and characteristic thoughts.



I have inserted the diagram above for my question. Now we all know that trees don't grow like CAD programs!

Now, here is where I need your help.

I am guessing the first dimension you can gather from a tree is the Circumference.

From there you can use the algebra to find the biggest square.
But, the tree does not grow straight up and I think that experience probably rules here.

So, say you have a tree that is 63" in circumference; What do you all think is the biggest timber you can gather from it? If you were to figure it algebraically then it would be no more than 12 3/8" square. But a tree doesnt grow like that.

If you all were walking the woods and found a tree 63" in diameter, what would be the biggest boxed heart timber you think you could get out of it (no sapwood please).

Explain please.

Much thanks!

Mo, you can't disregard the species with the aim of sap wood free timber, the sap ring will vary in species. As an example Red Pine has a sap ring of say 5", White Pine will be closer to 2" and Cedar will come in around 1".

Tim

this is good. thank you.

are those numbers based on diameter of 20". if so is there a percentage to each species?

this is such local knowledge that we're dealing with here- as in, it would vary depending on the soil under this particular tree compared to that one. so you may consider that the dirt, or place on a hillside or low spot will sustain this species better than that.

every conversation with my sawyer lasts at least 2 hours, because every tree has a story. maybe it had a few hard winters as a sapling. maybe a tree was skidded by it as it grew. my sense is this is the kind of thing that can be known in a rigorous way only after the fact and by inference.

and then there's the human, cultural element to the valuation of trees. like Ken's remark that fir is a foreign species in his parts. my dad taught me that balsam's were junk wood and not worth cutting except to thin or to make a bed, but man they hew nice and are favorites now. but maybe that's because we've moved south into northern ontario and they tend to be bigger trees here. cherry is good here, oak is generally choss. i think this is a question to be asked of every living tree, growing in a particular spot, with a specific use in mind.

and maybe in terms of joinery you can deal with a bit of wane for this timber, so that tree will do if you go at it with a drawknife here and there... apologies if i'm going off on this, but i do love the plasticity of trees.

The numbers are basically what I have seen over the past 15+ years of sawing wood. I would stand by these numbers. Once over a certain size/age tree, say White pine, the 2" sap ring will always be this size, yielding more heart wood as the tree grows. So, percentages would not be the solution. Just subtract 2" off the size of the tree, for White pine. Cedar, I would almost kill for a 20" log. Red Pine just simply has a lot of sap wood, a 12" log could easily have a 2" heart and 10" of sap. I don't know how souther pine stands up to Red pine in similarity, I bet it is close.

Tim

Heartwood formation begins with a bit of a lag, then tends to put on growth at a steady rate to the rate of growth of the tree. The other way you might think about it is this, cells live a certain number of years on average. How long? Count the rings of sapwood .

My white pine can have monster sapwood, our first 35 years or so on an open site can yield 2-4 rings per inch of rank growth, then the roots hit the rock of the mountain and the growth slows to 8-10 rings/inch, going through those zones the sapwood width will vary tremendously in inches but very little in number of rings.

I've been wandering in my stand limbing the pines up, they're mostly in the 25-30 year old range. In general they are running about the same height and diameter but the supressed trees in the stand are half the size of the normal ones so they will have more rings per inch and a narrower sapwood band. They're also struggling and not good timber, well neither are the big boys, they'll be sheathing or panelling. It's the northern red oak and white oak at their feet that I'm trying to show some light. Besides looking up, look down.

Hi Mo,

If you have a 63" softwood tree it is probably more than ready for timberframing. You could box heart, half or quarter the butt log on such a tree but be prepared for movement if halfing or quartering since this will release the internal stresses and the timbers will tend to banana in one or two directions. For softwood posts I would probably favour boxed heart especially if a lot of juvenille wood is present like Don describes above but if this were white oak then I would halve the timber (see my post on historic building photographs).

Timber from further up the tree will tend to be much more branchy with many more large knots and this should be box heart converted and will be much more difficult to work. Breaking down this kind of timber further will result in grading difficulties.

Regards

Ken Hume

Just the other day I sawed a White Pine with a sap ring less than an Inch. I bet it was stressed some how as per Don's input. The log was fine, I liked it for there was much less sap wood that would have stained up. This is out of the normal.

I wish I had more hard wood to choose from. I too ogle other stands of timber, the grass is always greener on the other side of the fence.

Minerals have great input as to the quality of the wood.

Tim

Mo,

Foresters, loggers, and sawyers all use the diameter on the small end of a log as the number that defines a log -- if you talk about a 63" log in our part of the world, people will pretty certainly be either confused or amazed.


As for determining the log size required for a certain timber, the math, as you said, is easy. Figure the length of the diagonal across the end of the timber and add a little for defects. You can use Pythagorus, you can use trig, you can measure it directly using a framing square and a tape or rule,you can draw it out full scale, and for square section timbers you can multiply the side length times 1.41. For an 8x8, I look for a straight 14" log, for a 12x12, a straight 18-19" log, for a 6x8, a straight 12" log if boxed heart. These numbers would be tip diameter inside the bark, not butt diameter.

As you know the percentage of heart to sap varies widely from species to species, (think yellow pine and oak). It also can vary widely within species if the trees grew under very different conditions -- fast vs slow.

With sapwood, the only way to know is to cut the tree down and look at the end. If you do it enough, you'll get a feel for what you're looking for, but there are no rules that would apply across different forest types and regions of the country.

Mo:

I'd also suggest you check out the Forestry Forum , where our own Jim Rogers is one of the moderators. They talk about forestry, of course, but there are also plenty of timber framers who will understand the specifics of your questions. CB.