Rift sawing a log vs. rift sawn lumber

[5quarter]

Bob...That's exactly right. although I actually cut directly through the pith and discard the small 1/2. of the log. The large "cant" might bow slightly (1/2" or less), but the boards will get edged before drying anyway. On a large log, there is generally not enough tension to overcome the mass of the large  cant. If you saw it radially, The resulting boards are wide enough that you will see very little crook from most of them. The few that are trouble can always be cut to shorter lengths and edged again after drying.

Chet

[scsmith42]

According to Gene's specs above,, if 80% of the board has the end grain at 75-90 deg, then it would count as quarter sawn.

#4 is certainly ~90 deg, so no question there.
#1 and #2 are probably in the spec as some of each board is ~90 deg and the rest is close.
#3 is more likely going to be classed as rift sawn.

Right, and all four graded and sold as "quarter sawn". And Andries included a pic of the crook that happens, due to growth stresses in a tree that increase as the tree lays on growth layers over time.



 

BT, it appears to me that the crooked boards in your photo have either sapwood or pithwood present along one edge.  My own experience is that if I mill a QS board and eliminate both sap and pith wood, the board will dry straight.

[scsmith42]

QUARTERSAWN
For hardwood lumber, quartersawn has three definitions.  Perhaps the most useful comes from the National Hardwood Lumber Association.  It applies to species with the ray fleck pattern on a radial surface.  If the fleck is visible on 80% of the surface (used for grading), then the piece is quartersawn.  This definition certainly helps satisfy the customer's desires when they quest quartersawn. In order to get the fleck pattern the annual growth rings, when viewed from the end grain, need to be between 75 to 90 degrees to the face...not part of the definition but rather what will exist.

A second definition says that lumber is either quartersawn or flatsawn (or plainsawn).  The definition of quartersawn is based on a ring angle of 90 to 45 degrees.  In this definition, there is no rift sawn.

A third definition says that quartersawn has a ring angle of 75 to 90 degrees, but does not require the ray fleck pattern.

What makes these last two definitions somewhat cumbersome is that a single piece of lumber can have different grain angles in different location, so at what location is the grain angle determined?  This makes the NHLA definition very good as it does specify location.  This grain variation is more common with lumber from smaller trees....that is, in the first half of the 20th century, the definitions did not have the complexity that they have now.

RIFTSAWN
RIFTSAWN lumber shows the straight lines of the annual rings on the wide face of the lumber, but the fleck is not there or does not dominate.  As such, the rings will make a 45 to 75 degree angle with the face, roughly.

FLATSAWN or PLAINSAWN
This lumber will show the annual rings on the wide face having a cathedral pattern, a large "v" shaped pattern, or a curved pattern.  It results because the wide face is somewhat parallel to the growth rings.  The extent of the pattern depends on the contrast that the growth rings have within themselves, whether the piece is sawn parallel to the bark or parallel to the pith, and if there is spiral grain. 

With small logs, it would be common to see flatsawn grain in the center of a piece of lumber and rift or quarter on the edges.

VERTICAL GRAIN
The term vertical grain is used only with softwoods.  It is part of the grading rules.  VG has rings that are at least 45 degrees to the face, so it is similar to rift and quarter hardwood grain angles.  The key advantages to VG are that the pieces wear better (more uniformity) and shrink and swell less in width.  The uniform, straight grain pattern is often considered beautiful.  VG is often sold as clear.  Clear, straight grain means strong wood, but VG alone does not provide increased strength.

SAWING PICTURES IN ORIGINAL POSTING
The pictures in the original posting do not have accurate labels.

LEFT PICTURE
The picture to the left is called live sawing or through-and-through sawing.  It provides rapid sawing, but in logs with stress, it provides pieces that are prone to warp in drying and that are likely to have varying thickness.  Further, the lumber grade of the pieces is lower than with other sawing methods.  The first piece or two from the outside of the log will be true flatsawn, or plainsawn, especially in a large log.  The next few pieces will be flatsawn or plainsawn in the center (widthwise) of the lumber and rift sawn, and even quartersawn, toward and on the edges.  That is, they are heavily mixed grain.  The two pieces in the center, the widest pieces, will be true, 100% quartersawn, as well as the adjacent piece on a larger log.  Although there will be rift grain in sections of many pieces, there will not be pieces of lumber that would be mostly or all RIFTSAWN.

So, live sawing is fast, with the log only having to turned once, but the grain pattern is mixed (which might be of concern to a customer), lumber thickness can be variable, grades will be low especially for the pieces near the center, warping in drying can be severe for some pieces, and every piece needs to be edged.  It is also not possible to produce a cant or tie.  (Tie prices continue to increase, making tie production favorable in many instances.)

MIDDLE PICTURE
This sawing pattern can be achieved by first splitting or cutting the log into four quarters.  The log is then held with a special jig.  In recent years, it has been called quartersawing, but it was not called that in the past...I suspect that it is an Internet invention or misuse of the term that has spread.  Indeed, the splitting of the log into quarters, followed by sawing is quartersawing if the procedure in the rightmost picture then is used.  That has been the historic use of the term quartersawing, as it produces quartersawn lumber.  The sawing pattern in the middle picture produces a lot of rift sawn lumber, with the widest pieces producing quartersawn.  If this were a softwood log, almost all of the pieces would be VG.  In fact, perhaps the error of calling this picture " quartersawing " was made by someone that thought VG and quartersawn lumber had the same grain patterns.  A more accurate title for the middle picture would be "VG Sawing" or "rift & quarter sawing".

RIGHT PICTURE
The right sawing pattern will produce 100% quartersawn lumber.  It is very inefficient--yield is low, labor is high and sawing time is long.  The title of rift sawing therefore has no relationship to the product produced.  From a practical point, this technique is difficult to do on most sawmills, but a few mills have special jigs.

The grain pattern of the two pieces shown under the picture is accurate for this picture (but not for the middle picture).

Hope this, lengthy discussion provides some clarity.  Any questions? 

Incidentally, there are a good number of pictures of lumber on the Internet that show the incorrect titles for the various grain patterns.  The best source is the grading agencies, as they have to be accurate and have to be full of reality and practical advice.

Gene, very insightful, as always.  As you alluded, there does not seem to be a standard definition of QS and RS lumber across our industry.

The defination of QS versus RS that I like the best is the one published by AWI (Architectural Woodworkers Institute).  AWI defines quartersawn lumber as having annual growth ring orientation between 60 - 90 degrees relative to the face of the board.  AWI defines rift sawn lumber as measured by annular growth ring orientation between 30 - 60 degrees to the face of the board, with 45 degrees being "optimum" (page 449, Appendix B, section 3 Lumber of the 2009 1st edition of Architectural Woodwork Standards with drawing from same posted above).

Here is the diagram from the AWI specs:



 

[dboyt]

When looking at the end of the log, draw an imaginary line perpendicular to the off-center line and never make a board that crosses that line. one side is in compression and the other side is in tension, and any board that crosses that line will make firewood. If you're sawing construction lumber from the log, do as magic suggests, as 2xs with crook are mostly unusable, where as bow and even twist can be used if you know what you're doing.

The hydraulic splitter gets more use than my shoulders do.  5/4, is this the cutting pattern you had in mind?  It keeps all the tension wood in one group of boards and compression wood in the other.  The "mixed" boards will warp.



 

[Magicman]

That is also the only way that I would saw that log.  The "mixed" is contained within the 6 flitches.  The other lumber might bow which generally will be taken care of with proper stickering, but no crook.   

I would wait for a pith centered log to QS.

[Andries]

dboyt, thanks for the diagram, it sums up the milling recommendations real nicely.
. . . and to add to MagicMan's comments, I'm thinking that the plain sawn board with the pith in it should be pitched into the edgings pile for some winter warmth.

[Magicman]

An off center pith log such as that will have sweep and the pith will probably reach at least 2-3 boards.  Boards that contain pith are still usable, you just have to pick the use.

[dboyt]

I even put questionable boards on the pile to air dry (on the bottom of the pile, they'll have a better chance of staying flat because of the weight).  If they're usable after drying, I consider that a bonus.  If not, I have some nice seasoned firewood.  Once you've gone to the trouble of making a board, you might as well give it a chance.

[5quarter]

Dboyt...yes that's exactly the principle. If I am not quarter sawing, I saw in that pattern. The only exception is that I toss the compression wood altogether in logs like The OP has. The exception is if I suspect Compression figure like you would find on the outside of a crotch. in those cases, I will saw 90° to what the diagram shows.

[kelLOGg]

5/4, is this the cutting pattern you had in mind?  It keeps all the tension wood in one group of boards and compression wood in the other.  The "mixed" boards will warp.



 

What rule-of-thumb do you use to decide the boundary between the "mixed" and compression/tension wood?
Bob

[5quarter]

Bob...If I'm sawing for inventory, I decide on a target width, say 12", and just take a slab off each side such that the pith is centered in the cant. Then I turn and saw down to the deck (Lumber crayons are your friend ). I've tried to make boards out of the "mixed" sections like Dboyts diagram shows, but they were almost always culled out after drying. And they're very tempting to keep cause they always look good coming off the saw. Unless I plan on nailing them up green, I don't even mess with them. If I'm sawing someone elses logs, I can't really do that, so I just caution them that the side boards may twist in the stack and leave it at that. In a perfect world, I wouldn't saw them, but we all know how that goes. ;)

[Chuck White]

That's a neat machine for making clapboards, seems to get it done systematically and quickly.

One (well a few) word(s) of caution though!
Those of you who use forks on your FEL please take caution at all times.  In the 5th picture, it looks like the chain could easily slip off of the forks at any time!

Be safe out there!

[GeneWengert-WoodDoc]

Thanks for the comments.

Regarding off-centered or oval-shaped logs:

FOR SOFTWOODS.  Virtually 100% of oval logs result because of compression wood (CW) in the "fat" part of the log.  CW, which is found only in softwoods, is wide ringed, darker colored and weaker than "normal" wood.  CW also shrinks lengthwise as much as 3% during drying, which results in bow, twist and side bend during and after drying.

Due to the dramatic strength loss in CW, it is not included in structural members when grading.

Almost all CW occurs early in the growth of the tree, so CW is in the juvenile core.  Juvenile wood is also weaker than normal, has steep slope of grain, and shrinks lengthwise.  Juvenile wood is likely to twist in drying, as well as bow and side bend.

FOR HARDWOODS.  Tensionwood occurs only in hardwoods.  It is more scattered throughout the stem rather than being in a pocket, like CW.  As a result tensionwood does not cause oval shapes.  Oval shapes in hardwoods seem to be more related to growth issues in the juvenile core.  Tensionwood is very weak, shrinks lengthwise, and is low in density.  It is high in cellulose.  Tensionwood is often characterized by fuzzing, due to its weakness, when sawing, planing, and sanding.  It is very absorptive, due to high cellulose content, so, when widely present, the absorption of stains when finishing is irratic, giving a blotchy appearance.  The effects of tensionwood can be handled by small changes in processing, except for its weakness.  Due to the low strength and low density when there is a lot of tensionwood, overall strength is low enough to result in brash failures at very low stress levels.

FOR HARDWOODS AND SOFTWOODS.  Juvenile wood is really a problem with spiral grain, lengthwise shrinkage, warping and lower strength.  It causes or is related to an oval stem.  Generally, from a processing standpoint, it exists for the first 15 years of growth.  Juvenile wood is a normal growth feature for every tree. But, juvenile wood is different compared to wood further away from the pith.

[Bigbo1234]

Not trying to put a wrench in anyone's gears, but you are all wrong. Quarter sawn only comes from a circle mill that has been stamped to resemble a giant quarter coin!!! Flat sawn is when the whole circle mill is turned sideways so the blade is laying horizontal, resulting in a "flat" cut!!! Cmon guys none of you knew this?

[Magicman]

Now if you really wanna start a Rift, you should know that a Circle Saw is not designed to saw anything.  It just travels in circles and always ends up where it started.  Kinda like an ole Goat that I know.

[goose63]

Most goats are like that :D

[dboyt]

Thanks, Gene.  I had always assumed that tension wood was on the uphill (tension side) of the lean.  So it is impossible to spot tension wood based on off center pith?  Are there any visual indicators that indicate whether a hardwood log has tension wood?  Of all the wood I've cut, I think Osage orange (hedge) is the worst for off-center pith.



 

[WmFritz]

Now if you really wanna start a Rift, you should know that a Circle Saw is not designed to saw anything.  It just travels in circles and always ends up where it started.  Kinda like an ole Goat that I know.

Some know him as a 'Goat'... some call him a 'Turkey.'





http://m.youtube.com/watch?v=WOlPFOsPmTg

[kelLOGg]

Dboyt, how are you gonna saw that?
Bob

[5quarter]

Hi Gene...thanks for the clarification. I was using the terms tension and compression to describe the stresses involved in the fat and thin side of an off-center log, much like you would describe whats happening when you make a muscle; the bicep is in compression and the tricep is in tension. even though it's all reaction wood, the two behave differently when sawing. How do we describe those two forces without causing confusion?
Dboyt...Wow! I've seen some bad ones, but that takes the cake.

[dboyt]

Yeh, that hedge was pretty extreme.  I squared out a cant, and excluded the wood within 2" of the pith.  It actually dried straight.  Hedge pretty much defies conventional milling and drying wisdom-- but I like it!

[GeneWengert-WoodDoc]

To shout and others...Tensionwood would perhaps be on the stretched side (tension side) of the hardwood tree stem, but it is found throughout the stem, which is against the old adage about its location.  I have also sen tensionwood restricted to certain growth rings.  As far as I know from reading and observation, tensionwood is hard to detect.  Note that growth stress can als be present and this causes a piece of lumber to "peel away" from the log when sawing.  I think that growth stresses and juvenile wood have more to do with oval shapes in hardwoods.  Now, it is possible that these also encourage tensionwood formation too.  Complex indeed.

[5quarter]

Gene...why would you want to shout at others?   ;) ;D ;D

[Migal]

Thanks Gene
           I saw the picture's and thought What The part where you explained about the closer to 90 deg from the face and fleck up to 60 deg was quarter sawed was a relief to me I've been taking a lot of time sawing a board turning and flipping one board at a time for over 2.5 yrs to get at least 80 deg to 90 deg from face boards and yes they crook but do lay flat and the fleck is perrrty and I brag on my Quarter sawed hardwood lumber to folks more than I should lol
thanks Migal
8)