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Log leveling

Started by D6c, October 29, 2019, 07:26:43 AM

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D6c

Normally I level a log to center the pith, at least by eye, but got to wondering, are there situations where you would cut parallel to one side of the log?

doc henderson

parallel to the bark give the best boards, but the center will end up being a wedge the same as the taper of the tree.  It depends if you are sawing for grade, or board feet.  centering the pith gives you a more stable slab from the center of the tree. @GeneWengert-WoodDoc  .  each has its place.  kind of like quarter sawing, it give a great look in oak and sycamore, stable in a different direction, but also more waste.
Timber king 2000, 277c track loader, PJ 32 foot gooseneck, 1976 F700 state dump truck, JD 850 tractor.  2007 Chevy 3500HD dually, home built log splitter 18 horse 28 gpm with 5 inch cylinder and 32 inch split range with conveyor powered by a 12 volt tarp motor

doc henderson

If you level it to the pith, hopefully the pith is contained inside a board. or if there is defect from it, fewer boards are affected.  
Timber king 2000, 277c track loader, PJ 32 foot gooseneck, 1976 F700 state dump truck, JD 850 tractor.  2007 Chevy 3500HD dually, home built log splitter 18 horse 28 gpm with 5 inch cylinder and 32 inch split range with conveyor powered by a 12 volt tarp motor

Magicman

Depends upon your cut list and what you want from the log.  Some piths are greatly off center of the log and if you centered the pith, you would get virtually nothing from the log.  Sometimes the log orientation and which face you open first is more important than the pith.  Some badly off centered pith logs may not be suitable to be sawn for the cut list and may have to be sawn for other purposes.

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GeneWengert-WoodDoc

HARDWOOD SAWING
If you saw parallel to the pith, this is called half-taper sawing.  If you saw parallel to the bark, it is full-taper sawing.  The big issue is time to saw versus lumber value.  

Oftentimes, the best solution is to open the log on the worst face with no taper.  This means that the opposite face will be sawn full taper.  So, the taper in the log is taken out in the low grade opening face portion, while the high grade portion on the opposite face has full length lumber.  This technique gives the highest valued lumber.  (An alternative is to open the best face with full taper, and then no taper when flipped 180 degrees.)

Half-taper studies show that you get the lowest yield of higher grade lumber.

Live sawing, also called through and through sawing, is fast, has wide but cup prone lumber with some rift and quartered and gives high footage yield, but grade is low and every piece needs edging.

For a high quality log, rather than eliminate taper in the high grade portion of the log, full taper saw until the grade drops (or stress causes bend in the log) and then flip 180 degrees and full taper saw again.  Then, take the taper out of the log, in one cut usually, in the lower grade part of the log.  This means about 20% higher value overall.

For a low value log, anything that saves time (without making things unsafe) is the best choice.  So, live sawing and no taper is often best, along with sawing just one large cant or tie.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

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Brad_bb

I virtually always center/level the pith in both directions cutting hardwood.  I'm most often getting a beam out of the center.
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D6c

Interesting comments...I'll have to consider full taper sawing, especially on hardwood logs with lots of taper.
Read through some other threads also that talks about full tapering all four sides, leaving a "Washington monument" shaped waste out of the center where the lowest grade is.

With a band mill, once you've got the tapered cant started, you could roll and cut the best face without having to level the log.  By putting the face to cut down, and cutting a board off the bottom it would be pretty easy.  I've done this when quarter-sawing...alternately cutting boards off the widest face of a quartered log by flipping the side to cut down until the grain is slanted to rift and gets too narrow.  Cutting off the bottom doesn't normally even require clamping the log, since the cutting force is down low, it doesn't have a tendency to roll the log.

YellowHammer

Full taper sawing provides the flattest staying, best behaved boards for high grade hardwood lumber, which stay flat, don't twist or bow, throughout the end of the drying and retail sales process.  I saw full taper on virtually every log, however, the tradeoff is that the pith is not centered and not parallel, so full taper sawing it isn't best used when getting side wood and trying to end up with pith centered posts or crossties.  In my case, the pith boards are not my target goal.  I will saw full taper and zero taper on the same log, as Gene describes, if the log quality warrants it.  

When full taper sawing on logs, there are generally points in the process where the pith wood can be used to zero the angle for the opposite side of the cant so you don't end up with a pyramid.  Since I use the pith sections for cutting the wedge shaped cleanup boards, I don't worry about the waste. 

Some logs react differently to parallel bark sawing so they don't have to be quite as well done.  For example, basswood can be cut pith centered and still turn out OK.  Hickory, not so much.  
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Biocmp

This is a great discussion and the information is much appreciated!

mike_belben

The hickory handle mill is closed now but they were trying to saw parallel to the best grain and to box the defects into reject pieces, many of which were tapers from the interior of the tree.  I think they were willing to level and saw in any manor that gave the best sound blanks.  


My conclusion from observing the reject blank bundles i bought for firewood is that shake and rot tubes were probably the hardest stuff to contain due to their random nature. 
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Joe Hillmann

I know this is an old post but, right now I am sawing out a log cabin.  The wall logs are D logs and I make two parallel cuts to the pith of the log to give me an 8 inch tall log.  And the third cut I make parallel to the face of the log I want to keep round that way the log is consistent.

The rafters are round timbers with one sawn face.  On them I am sawing parallel to the top of the log so when I am done the final rafter is several inches thicker at one end than the other.

I have also sawn specialty items/cuts where I have propped up the log to be at a 30-45 degree angle to the cut to make plaques and long angle cuts when needed.  It could also be used to get some really cool grain patterns in the finished boards.

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