A big log is not a small log scaled up. Three things change, and all three change what you can do before you have made a single cut.
The Arithmetic of Width
My mill will cut a board 36 inches wide. Getting a 36-inch cant out of a log takes a log over 41 inches, because you have to lose the round off four sides to get there. That gap between what a tree measures and what it yields catches people out constantly.
And it is the short diameter that decides it. A tree grows away from competition, so it is an oval, not a circle — measure the generous way and a 44-inch tree can still fail to make 36. Measure both, and believe the smaller one.
The Arithmetic of Weight
Green white oak runs about 63 pounds a cubic foot. A 15-foot butt log at 36 inches is therefore somewhere around 6,700 pounds — past what a trailer will legally carry once the trailer's own weight comes out of the rating, and well past what can be handled casually. Buck that same log at 8 feet and it is roughly 3,600.
So on a big tree, the bucking decision gets made before the moving decision, and both get made before anything is sawn. Weight is also why getting it down to about 30 per cent moisture matters for handling long before it matters for furniture: that first stretch of drying takes about a fifth of the weight off, risk-free.
The Consequences Are Bigger Too
A large tree has grown through more history. Wind exposure changed, neighbours fell and let light in, lean developed and the tree laid down reaction wood to compensate. Density can differ substantially between the heart and the outside. None of that is visible from the end of the log, and all of it turns up as the log opens — which is why the breakdown is staged rather than routine.
Reaction wood in particular releases stress as it is cut. On a small log that means a board that moves. On a 6,000-pound log it can mean the cut closing on the blade. The roundest logs go first, not the biggest — see what makes a tree worth milling.
What the Size Buys You
Width you cannot buy anywhere, and the cathedral figure that only a wide flat-sawn face off a big log can carry. It also buys options: a log this size gives quarter and rift near the heart and plain sawn on the outside out of the same tree, which is on quarter sawn, plain sawn and rift. And a slab can always be resawn into boards later, while a boarded log can never be made back into a slab — so on anything with the girth, slabbing is the cut that keeps both doors open.
The 36-inch width and the 20-foot track on my mill were both specified for this, because they are the two things a commercial mill will not do. What comes off the whole tree is on the frugal milling page.
Contact
Old Growth Mill
Axson, GA 31624
Email: [email protected]
Phone: (912) 310-0650
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