A few years ago a huge white oak tree fell on my rental house. I got three 8' +/-logs out of it and also a limb about 11' long that was around 24" in diameter. I had the logs quarter saw and the limb slabbed. I am considering making one of those river slab tables out of the wood from the limb. LIMB may be the wrong term. It was nearly vertical and was probably the trunk from above the first crotch. I digress in my elaboration. The two book matched slabs I have are crooked and I plan to use them like a Ying/Yang symbol.
My question is: Is there any significant difference in wood in the limb. Bizarre shrinkage characteristics?
>>>Is there any significant difference in wood in the limb. Bizarre shrinkage characteristics?
I've cut and sawn some huge red oak "limbs", maybe 22" in diameter. These were essentially vertical on the tree, straight grain, growing from a main trunk about 4' in diameter. In my experience a straight vertical limb is the same as a straight primary trunk. You can get various warping problems if the limb (or trunk) is leaning, bowed, or twisted.
Note that the way a partictular plank is sawn from even a straight log relative to the grain and pith can also affect both how it warps when drying and the seasonal movement.
If the wood is relatively vertical most tree people would call it a stem if it splits off from the vertical trunk. A limb would be growing off at some less than vertical orientation. Also, consider relative diameters above and below the union.
There will be reaction wood in any leaning wood, especially branches. Compression and tension wood is interesting from a tree structure view. Amazing biological engineering.
when reaction wood is milled that internal energy is released. Lots of variables but there is a good chance of twist/cup/bend or other degrade.
If you milled the wood and its ready to work my guess is that its stable.
If you look at the butt end of a log and see that the pith is off-center its a sign that there is reaction wood. Be warned you could be making nothing more than fancy firewood.
I have got to pull these pieces out and check them.
They have been on the bottom of the pile of the rest of the tree to help to keep them flat. I do not remember how long they have been drying. I had a broken hip at the time so I suppose I could check my medical record or perhaps find out from the insurance company when the tree fell on the house. In light of the fact the house was unoccupied my only regret is that it did not completely total the house. I could have built a new one rather than repair this one.
You probably can't see it in this low res picture but there are several off center logs to be seen.
Several factors can make a tree put on growth on one side more than another. It is common to have asymmetric logs on the log yard. Given how common these trees are if they were a problem when converted to boards (1) we would see more problems than we do and (2) mills would reject these logs and they certainly don't.
A common cause of asymmetric centers is timber that has regrown from stump sprouts. In a cluster of 2-3 trunks the inside of all the trunks will have grown less than the outside. I have never detected any difference in the lumber from these trees. Logs from above a fork will be similarly asymmetric. I recently worked cherry lumber for two forks above a crotch. It was normal.
I have converted several thousand bdft of hardwood lumber into products. A board that misbehaves is exceeding rare. I have planed tens of thousand bdft of lumber and again it is rare to encounter an atypical board. I have no doubt that this some of this lumber came from "leaners" and more from asymmetric centers. Either "reaction wood" is rare in commercial lumber or it is not the problem it is said to be.
If the pith is off center I would suspect this may be reaction wood. The danger happens when you rip the wood and the internal stresses in the wood try to close the saw kerf behind the blade if the wood pinches a circular saw blade it could kick the wood back at the operator with great force .
The safe bet is to rip with a band saw ¼ inch outside the final size and then rip on the table saw to size, as there is no danger of kick back on a band saw and ¼ inch wide part cannot generate enough force to pinch the blade.
The reaction wood I'm familiar with is from open grown urban trees not woods trees. I see it more in true branches or trees that are heavy leaners. In branches it looks like the tree 'melted' and sagged the growth to the bottom of the branch. If a branch were 12" diameter the center/pith would be at 3" not the 6" mark.
Early in my career I learned to consider reaction wood when I was felling a leaner or cutting off a branch with reaction wood. I had trees/limbs 'pull' in an off-angle that I didn't understand at first. When blocking up logs on the ground or cutting off limbs I'd find that fibers would 'spring' back like bristles on a broom in leaning wood and branches. My Dad turned wood. He told me that he found odd movement in very off-center chunks too.
All that said and done...Bill's milling experience is more the norm. Those are woods trees not urban trees. I doubt that many crooks or branch butts would be left on the log anyway because they aren't straight.
Your responses are reassuring. I have been wood working at some level over fifty years. I have seen a few, very few reactions that I would attribute to reaction wood and maybe more likely drying stress. I remember ripping a softwood 2 x 6 that probably had the pith and juvenile wood in it and the two pieces sprang apart several inches to the point I was concerned about the blade and fence and the rips were so crooked as to be useless. I also remember a few cases of wood pinching the blade as it was ripped. And there have been a few pieces that warped in a few hours after milling.
These have been few and minor problems.
This question was prompted by my concern about typical limb wood, wood grown more horizontal than vertical. It's easy to visualize the off center pith in such wood and the possibility of there being reaction wood. As I was typing my question I realized that my piece is more likely to be the continuation of the truck of the tree above the first major branch, grown nearly vertical but more crooked that a really desirable log.
I appreciate the discussion and thoughtfulness of the answers.
The pieces I am concerned about are about 3" thick, 24" wide and 11' long. I will not be passing them over a table saw OR through a bandsaw.
My plan is to mill them thinner, probably with a router sled, and to shorten them, probably with a track saw and then nest them together to form a table top. My concern is that the milling will cause them to turn into potato chips. I will probably mill them in two stages, letting them rest a week or two in between.
I understand there is a spring loaded riving knife. How can you be sure it is in the kerf?
Anyone that has seen a kick back understands how massive the amount of energy is transferred from the blade to the wood and or saw in the blink of an eye.
I have not fully, at least not at full price. I have been accumulating some at estate sales and auctions at a third to half price of new. I scoffed at them for years and at full price. I have to admit I am impressed with the quality of what I have. They have become my go to tools. (Tracksaws, router, Domino, 6" Rotex sander, 5" ROS, Vacs) Not going for the Kapex saw, motor gets bad reviews and I like my Makita. The Rotex sander and Domino are especially impressive.
Does it have something to prevent kick back?
It does have a riving knife.
Can the saw lift off the track?
Yes, My understanding it that other brands have an interlock to prevent the saw from tipping off the track when making miter cuts, but Festool has not added that feature.
Can the saw move backward on the track?
Yes. Also, the router can use the track, lots of possibilities there.
How securely is the track attached to the wood?
Very Secure. The tracks have soft rubber grip strips on the bottom and many advocate simply laying the track in place and making the cut. There is also a slot or key way in the underside of the track that allows for the use of clamps. Similar to F clamps. I generally use them, securing both ends of the track. Certainly on any critical cuts.
I understand there is a spring loaded riving knife. How can you be sure it is in the kerf?
I don't know. You can look, but I never have.
Anyone that has seen a kick back understands how massive the amount of energy is transferred from the blade to the wood and or saw in the blink of an eye.
I have been wood working for over fifty years. When I was a Builder (13 years) I framed at least fifty houses personally. Huge experience with a circular saw. Have had a shop most of that time and built lots of things. You are correct, kick backs can be startling, powerful, and dangerous. Whether from a circular saw, table saw, router or any other tool. But I don't see how a tracksaw adds to the problem.
