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Face centered vs. log centered pith - revisited

Started by kelLOGg, August 06, 2016, 09:43:34 PM

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Ricker

Kind of related topics this topic, I have a order for 120 4', 6"x6" hemlock that will be used by a contractor for blocking when jacking up houses and barns to replace sills, stringers and such.  The question is do I need to worry about centering the pith for a job like this? The short stuff I have around the mill doesn't' seem to have moved very much. I would hate to think how much side lumber I would have if I only got one 6x6 per log.

drobertson

Pretty sure you are good to go on maxing out the yield on the short ones,
only have a few chain saws I'm not suppose to use, but will at times, one dog Dolly, pretty good dog, just not sure what for yet,  working on getting the gardening back in order, and kinda thinking on maybe a small bbq bizz,  thinking about it,

Engineer

I agree, if you're just doing blocking, cribbing or ties, doesn't matter.  Get the best yield you can out of the log.  For timber framing, though, centering the heart is pretty important.  It helps (but does not guarantee!) that the timber will stay reasonably straight and will shrink evenly in all directions while drying.  The side lumber, for me, is a major bonus - I have a use for it. 

scsmith42

Quote from: kelLOGg on August 08, 2016, 09:03:21 PM
Since cathedral grain tracks and locates the pith within the log I would expect that at the very ends of the log the cathedral grain would always be centered in the face of a cant provided it has been sawn with the pith centered at the ends. If the log is straight the cathedral grain (and hence the pith) maintains that center position down the log. If the log has sweep I would expect the cathedral grain to deviate from the center position at the end of the cant and follow the sweep. That's what I expect but it is not what I find in the pics below.

The 1st shows the centered pith and the cathedral grain also centered at the end of the cant. However, the 2nd pic (of an adjacent face of the same cant) shows a centered pith but the cathedral grain is not centered at the end of the cant. This is unexpected to me. Can anyone explain? These are 6 x 6s.
Bob




  




Bob, take a close look at the end of the log with the off center pith.  If you look in the lower right corner of the cant you will see that the growth rings are very close together; whereas on the upper left side of the cant they are 2X further apart.  Typically you see this on a leaner or at the point where a tree bends significantly in growth.  Based upon the offset cut in the end of the log, I would estimate that this is the butt end of the log and it was a situation where the bottom few feet of the tree grew at an angle and then straightened up (or it came from a forked tree).
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kelLOGg

Scott, the pith in the log was very off center so it certainly was not ideal for a beam so I centered the pith in the cant and tried to get what I could. So, in general, can I expect only a straight log to exhibit the cathedral grain tracking the pith? I want to be able to explain to my customer just what he might expect in his beams as to which ones might bend on drying.

Another general question that has occurred to me is: "Does it matter how you open a log if all you want from it is a beam?" Assume the log has some defects like some sweep or a knot or is just not ideal.

Bob
Cook's MP-32, 20HP, 20' (modified w/ power feed, up/down, loader/turner)
DH kiln, CatClaw setter and sharpener, tandem trailer, log arch, tractor, thumb tacks

terrifictimbersllc

Quote from: WDH on August 09, 2016, 08:30:18 AM
Yep, logs are almost never perfectly round.
Square logs are the best for quarter sawing. :)
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WDH

Woodmizer LT40HDD35, John Deere 2155, Kubota M5-111, Kubota L2501, Nyle L53 Dehumidification Kiln, and a passion for all things with leafs, twigs, and bark.  hamsleyhardwood.com

Okrafarmer

Quote from: WDH on August 11, 2016, 07:51:59 AM
I prefer the 8-sided logs for that  ;D.

yes, I was going to say, the square ones are good for straight-through sawing. The last little pie shape pieces left over from qs-ing an octagonal cant can sometimes be used to make bow staves.
;D
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Rougespear

Quote from: kelLOGg on August 11, 2016, 07:35:59 AM
Scott, the pith in the log was very off center so it certainly was not ideal for a beam so I centered the pith in the cant and tried to get what I could. So, in general, can I expect only a straight log to exhibit the cathedral grain tracking the pith? I want to be able to explain to my customer just what he might expect in his beams as to which ones might bend on drying.

Another general question that has occurred to me is: "Does it matter how you open a log if all you want from it is a beam?" Assume the log has some defects like some sweep or a knot or is just not ideal.

Bob

To your question Bob: (I am far from an expert though!) when I am opening a small log from which I want a beam, my opening face is most always on the long side of the beam whose face is closest to the outside of the log, at a depth no closer than one board thickness (e.g. one 4/4 board) away from my finished dimension above the pitch.  For example: I have spent the last week sawing 14' 4x8s.  The pith most always favors (or in other words is off-center) one side of the log.  I draw my 4x8 on the end of the log where it will best fit and have the pith "as centered as possible".  I rotate the log and open it on one of the 8" sides that is closest to the edge of the log.  I am always trying to stay either a 6/4 or 4/4 board away from the finished 4x8 timber.  Where possible, I try to saw the "horns" off of sweepy logs first, but I am more and more simply avoiding logs with sweep: they make good 2x6 T&G material.

Hope that helps a bit. 

Cheers, Brent
Custom built Cook's-style hydraulic bandmill.

customsawyer

Are you cutting these out of pine or hardwood? The wood moves a little different in each.
Two LT70s, Nyle L200 kiln, 4 head Pinheiro planer, 30" double surface Cantek planer, Lucas dedicated slabber, Slabmizer, and enough rolling stock and chainsaws to keep it all running.
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kelLOGg

Quote from: customsawyer on August 12, 2016, 03:36:49 AM
Are you cutting these out of pine or hardwood? The wood moves a little different in each.

It is pine.
Cook's MP-32, 20HP, 20' (modified w/ power feed, up/down, loader/turner)
DH kiln, CatClaw setter and sharpener, tandem trailer, log arch, tractor, thumb tacks

WDH

Woodmizer LT40HDD35, John Deere 2155, Kubota M5-111, Kubota L2501, Nyle L53 Dehumidification Kiln, and a passion for all things with leafs, twigs, and bark.  hamsleyhardwood.com

kelLOGg

Brent,
If I understand correctly, you open the log on the side where the pith is nearest to the bark. So, if your mill cuts off the top of the log you orient the pith up for the first cut. Right?

Bob
Cook's MP-32, 20HP, 20' (modified w/ power feed, up/down, loader/turner)
DH kiln, CatClaw setter and sharpener, tandem trailer, log arch, tractor, thumb tacks

customsawyer

In your reply #16 in the second picture I would bet your cathedral grain on the bottom of the cant is off center to the right in the picture. If you draw a line from the cathedral grain to the pith just keep drawing that strait line and it will be pretty close to where the cathedral grain is on the bottom face.
Two LT70s, Nyle L200 kiln, 4 head Pinheiro planer, 30" double surface Cantek planer, Lucas dedicated slabber, Slabmizer, and enough rolling stock and chainsaws to keep it all running.
www.thecustomsawyer.com

4x4American

I never paid much attn to that cathedral grain pattern being centered or whatever, but now that you brought it up, I was noticing it in some oak I was sawring today
Boy, back in my day..

Rougespear

Quote from: kelLOGg on August 12, 2016, 03:45:19 PM
Brent,
If I understand correctly, you open the log on the side where the pith is nearest to the bark. So, if your mill cuts off the top of the log you orient the pith up for the first cut. Right?

Bob

That about describes it... in far fewer words! Haha.  Doesn't mean my way is right though, it's just another "way".
Custom built Cook's-style hydraulic bandmill.

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