When someone asks me about cutting their own trees to make their project frame, I usually suggest that they start with the frame design.
When that's done we get a stock list of timbers needed to create that frame. The timber list show us the sizes of the timbers.
8x8x16' for example
From the timber stock list we then create a log list. A log list tells us the diameter of the log, as mentioned on the narrow end of the log, the top end of the log as it stood in the tree on the stump, inside the bark in inches. For example an 8x8 needs a log of 11 5/16" in diameter or larger by the length, such as 16'.
So my log list would say X number of logs 11 1/2" x 16' or larger.
That way a logger can measure the diameter inside the bark on the narrow end and see if it makes the wanted timber. Of course this is done after the tree is felled. If this current log isn't large enough for this targeted timber then it may make a timber of a smaller size. And he can check off a smaller log needed from the list. Then look for a larger tree to fell to make up for it.
It is very hard to estimate the diameter inside the bark of a log in a tree that is 16' or higher above the ground.
When we harvest trees and create logs from them for the frame we usually add an extra log or two of each size on the list to make sure we have enough stock on hand should one or two logs have some internal defect not seen until opened up. And with the extras we can then have plenty.
When we start milling the logs I like to start with the largest longest sticks first. That way we can get the hardest to produce off the list and work our way to the smaller easier ones.
If we have picked a log for making a 8x8x16 and we can't get an 8x8x16 out of it, because of some circumstance we didn't see, I would then look at my timber stock list and see if I can make it into some other timber on the list.
If the log had a crack in it from the felling or landed on a stump and had an internal break, it may not show up until it's milled. We could then cut it back to make a 8x8x12 or maybe a 6x6x16, like that.
There are ways to visually estimate the volume of timber in a standing tree. But this is something that the average person may not have the needed experience to do, easily.
Professional forester are usually the ones who do that.
There are tools used for doing such things, such as cruising sticks and diameter tapes as well as charts that state the volume per 16' length of the tree.
A diameter tape is used to measure the diameter of the tree at the correct elevation off the ground. This elevation is known as the "diameter at breast height" usually noted as dbh. With a dbh chart of values you can estimate the volume of lumber in a standing tree, once you decide how many 16' lengths are in that tree. This can be done by standing back from the tree and holding up a stick at arm's length that would equal 16' at the tree. I don't have a picture of someone doing this but I can try and find one.
I suppose that theoretically you could use this to determine log size but again it's very difficult to do.
As mentioned one has to weigh what they want to do with their timber stand.
Do they want to improve the stand for future generations? If so then when the do a harvest for their frame they may do a "timber stand improvement" or TSI cut. This means you usually remove the undesirable trees.
We were taught by our local county forester to remove the "four D's". Some of these trees are the dead, the deformed, the deceased, or the dominate. Some of these trees, from the first three "D's" may not be good enough for timber framing. But if you want an even height canopy you may want to remove the dominate trees. And these can be large over shadowing monsters who can have large trunks and yield some great lumber or timber.
Wow, what a long post......
I guess I'll stop now.....
