How milling impacts figure
What I'm asking is: does the tree determine how much figuring to expect, or does the sawyer? I realize the answer is both, but how much does nature have to do with the figure? If I could theoretically cut all red oak logs, regardless of age, growth rate, growing conditions, health etc. at exactly vertical, would they all show equivalent figuring?
It's possible you have 1/4 sawn lumber that is what is called "rift", which doesn't show the typical figure that some people prefer.
I cut a lot of quartersawn. Here are a few things that will give you the effect you described:
(1) The comment on curved rays is right on the money--you hit the ray at different angles as measured across the face of the board, thus not producing a fleck across the face of the board.
(2) If the log has any curve to it on the outside or if the very center (the pith) has much curve, you will hit the medulla rays at an angle (relative to their length along the length of the log). Although you may be parallel to the rays at the end of a board you will be at a different angle further along. However, this only will effect one plane of your cutting, assuming your log has bow or curve in only one plane.
(3) Beware the spiral or twisted log/grain. Even if everything looks right you will not be hitting the rays flat along their length because the rays themselves are at an angle relative to the face of your board. This lumber is also very prone to twisting as it dries, because of the grain angle. This is a very common trait amongst the red oak in the midwest.
(4) When you set up the log on your saw you MUST be parallel with the center (pith). This also holds when you turn the remaining 1/2 log that you need to be parallel with the pith even if you have removed it prior (I usually mark the center on the remaining halves before they are removed from the log).
(5) I've observed that some logs have more rays, some have thicker rays and some have longer rays. Red oaks typically have shorter rays than white oaks (commonly 3/4" and longer) as measured along the length of the log. (This is also a good way to determine species when dealing with rough weathered lumber. Hopefully Gene can shed some light as to how species affects number and size (thickness) of medulla rays).
(6) Log size has a role with regard to the amount of quartersawn compared to rift (vertical grain with no ray fleck). We typically saw 20-40" logs for quartersawn. Of this only 2-3" on either side of center produce good figure. After we have split the halves, removing the quartered leaving four quarters with only rift sawn faces, we then split the quarters in half, giving us a quartersawn face that we finish sawing out parallel to. We have far more customers for quartered than rift and this allows us to cut almost entirely quartered out of a log. Without doing this we would have to produce some rift.
I agree with the above posts, but keep in mind that you are using 60 to 90 degrees. The NHLA rules say quartersawn is 70 to 90, and even at that to get consistent heavy flake you have to be pretty close to the 90 degree mark.
I agree with comments #3 and #5 especially as being the reason for variation in figure.
Just to clarify, quartersawn oak is defined by the NHLA as oak with substantial ray fleck (or figure) regardless of the ring orientation. So, it is what it looks like--I like this definition as it is practical and beneficial with a strong customer orientation.
Gene Wengert, forum technical advisor
I do a bit of modified quarter sawing (cut off and resaw the bottom and top thirds of the log). I notice that only those boards that are very close to 90 degrees show good figure.
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