Wood Tension

[Sean Troy]

Is Qwtr. sawn White Oak known for having tension and releasing when you rip it? I had to walk away from the shop yesterday after trying to rip some. I could not get a straight piece of wood to save my life. Sean

[dan petroski]

it depends on where the tree grew. if it grew on a slope it will have stress in it. if it grew on flat ground it won't. just try standing on an incline and see how much strain you put on your body

[Gene Howe]

Weird.
Been working with QSWO for many years and have never encountered tension. In fact, just the opposite. Very stable.
I guess mine has all been grown on flat land.:D

[Kent A Bathurst]

Is Qwtr. sawn White Oak known for having tension and releasing when you rip it? I had to walk away from the shop yesterday after trying to rip some. I could not get a straight piece of wood to save my life. Sean

It can. AFAIK, any wood can. I've had some that didn't, some that did - but very little, and some that did a lot - "lot" being relative. I always rip oversize, and then come back a couple days later to joint. I tend to buy higher-grade stuff [old growth, very tight rings, grown only on the north side of magic mountains where hobbits and wizards live, that type of stuff]. QS-Anything should have less movement, I think, than flat sawn.

[Sean Troy]

I've been letting it sit. I'll try cutting again later today and see what happens.

[Howard Acheson]

It is more likely that there is uneven drying of the wood. The outside surfaces have dried to a lower point than the interior. When you rip, you are exposing the interior which, being at a different moisture content is causing the warping.

This is the reason many wood workers acclimate their wood to their shop environment for 3-4 weeks before machining it.

[Ken Fitzgerald]

Where it grows on the tree can have an effect too.

I know of a renowned turner who will not turn any wood that he knows was a limb. Growing horizontal and fighting gravity will put more internal stress on wood.

[michael case]

Sean,

I went through $75 of mahogany trying to make rails and stiles once. It does depend on the tree, but it is more unusual in QS white oak. It was good to walk away, but for when you go back here's a suggestion on the assumption the bend you mention is crook and not bow. Joint your fence edge. Rip the piece at least 1/4" over size. Joint out any crook that results. Set the jointed edge to the fence and take off another 1/8". Again, Joint out any crook that results. set your joint edge to the fence and make your final rip. It takes time, (its easier to do a number at once in this sequence) but it usually work with a difficult board.

[Sean Troy]

Sean,

I went through $75 of mahogany trying to make rails and stiles once. It does depend on the tree, but it is more unusual in QS white oak. It was good to walk away, but for when you go back here's a suggestion on the assumption the bend you mention is crook and not bow. Joint your fence edge. Rip the piece at least 1/4" over size. Joint out any crook that results. Set the jointed edge to the fence and take off another 1/8". Again, Joint out any crook that results. set your joint edge to the fence and make your final rip. It takes time, (its easier to do a number at once in this sequence) but it usually work with a difficult board.
I will try that when i get back out in the shop, Thanks

[glenn bradley]

I've been letting it sit. I'll try cutting again later today and see what happens.

If its any consolation, I got some real action out of a piece of mahogany that was part of a batch that had been in the rack for 2 years. The rest of the batch was fine. I get about the same ratio on QSWO; just when you're starting think it never happens, it does. Not often but it happens.

[Scott T Smith]

I produce quartersawn oak extensively with my sawmill. Occasionally, a log will have so much tension that the board will lift itself up off of the log as I am milling. Sometimes it can bind the sawblade and I have to back out of the cut and start over.

Those boards are set aside for trailer decking...

You can usually pick out which logs have tension in them by looking at the relationship of the pith to the circumfrance of the log. Logs with significantly offset pith will usually have a lot of tension.

Tension also can occur at the upper end of a log if the limbs branched out in a fork. In this instance, the tension is usually localized within a few feet of the end of the log.

Although quartersawn wood is typically the most stable wood, it can still have tension if the tree grew at a slant.

As Howard mentioned, most tension is due to drying stresses, and is more prevalent on thicker boards and planks (8/4 or greater).

Limb wood is typically not used to produce boards, for the reasons that Ken mentioned.

[Eiji Fuller]

Sean,

I went through $75 of mahogany trying to make rails and stiles once. It does depend on the tree, but it is more unusual in QS white oak. It was good to walk away, but for when you go back here's a suggestion on the assumption the bend you mention is crook and not bow. Joint your fence edge. Rip the piece at least 1/4" over size. Joint out any crook that results. Set the jointed edge to the fence and take off another 1/8". Again, Joint out any crook that results. set your joint edge to the fence and make your final rip. It takes time, (its easier to do a number at once in this sequence) but it usually work with a difficult board.

This is the method I use for dimensioning all my boards. I just take internal stress in solid wood for granted. I'm actually suprised if a board doesn't move after being ripped from a larger board. For this reason I like to rip on the bandsaw instead of the tablesaw. Even if the board pushes away from the fence there is no binding, burning, or possibility of kickback. Ill usually then joint then plane to my final dimension if it's 5" or less in width. Anything wider and I'll rip the final 1/32 over and then joint that overage off the cut side.