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Milling beams out of a log.

Started by Joe Hillmann, March 10, 2014, 09:16:41 PM

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Joe Hillmann

I am trying to get as many 4 x 12's out of a two 20" logs.  Once I have them canted up do I need to worry about where the beams are in relation to the center of the log in order for them to stay straight and reduce warping?  I did a quick google search and couldn't find much info when it came to milling beams.


Den-Den

You will likely get responses from more experienced sawyers but my take is to make the beam either centered around the pith or well away from the pith.  If the pith is near one edge of a beam, it almost certain to warp.
You may think that you can or may think you can't; either way, you are right.

thecfarm

I did a search on centering the heart on here and came up with a few hits. Go up to the top of the page,right above news type in centering of the heart,change This Topic to This Board,because you are on the sawmill board and press search.
Others will be on to help no matter what.
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shinnlinger

Den has the basics.   It can vary by species and how quick you do whatever your doing with the board, weight on the pile etc, but you do not want to split the pith!   Visualize a 4x 12 around the heart and then work down to it.   You won't get as many 4x as you might have hoped but they will be much straighter. 
Shinnlinger
Woodshop teacher, pasture raised chicken farmer
34 horse kubota L-2850, Turner Band Mill, '84 F-600,
living in self-built/milled timberframe home

hunz

I second what everyone has said here. I can only speak for white pine beams as this is my experience. Another issue I have found, is that if a beam edge is near the heart, it will tend to check a lot on the end of the beam. I was looking at my stack yetsterday, and I took note of this. Beams that were cut clear of the pith, or had centered it had virtually zero end check after 1.5 years air drying. Hope that helps!
Dream as if you'll saw forever; saw as if you'll die today.



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Joe Hillmann

Quote from: shinnlinger on March 10, 2014, 09:33:37 PM
Den has the basics.   It can vary by species and how quick you do whatever your doing with the board, weight on the pile etc, but you do not want to split the pith!   Visualize a 4x 12 around the heart and then work down to it.   You won't get as many 4x as you might have hoped but they will be much straighter.

So if out of a 20 inch log I could get a 13" cant (assuming a perfect log) Would I cut the can't to 12x12 then cut three beams out of it  with the heart/pith of the tree being in the center of the center beam?  Should the outer two beams be left as beams or should they be cut into boards so I only get one beam from the log?

Magicman

I would target one beam with the pith as centered as possible.  Then take one more from each side of that one.  That makes three.  As shinnlinger stated above, do not split the pith.
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scleigh

The pith may not be centered and there could be taper in the log that will not allow more than 3 beams per log.

mesquite buckeye

Any sapwood, especially if off center or only on one edge will greatly increase curvature with drying. :(
Manage 80 acre tree farm in central Missouri and Mesquite timber and about a gozillion saguaros in Arizona.

LittleJohn

Don't forget to account for blade kirf

Joe Hillmann


I don't actually know the sizes of the logs I have (I was just given them on Friday)  I was told there are 6 to 8 logs that are 16 to 20 feet long.  When I went out to look at them only one end of one was visible through the snow.  More than anything I was using them as an example of what I should keep in mind when sawing beams out of logs to get the best quality.

Joe Hillmann

Quote from: mesquite buckeye on March 11, 2014, 12:49:07 PM
Any sapwood, especially if off center or only on one edge will greatly increase curvature with drying. :(

That is good to know,  Is there any rule of thumb when it comes to how far you want to stay away from the sap wood or doesn't it matter as long as there is no sap wood in the beam?

mesquite buckeye

Seems like sapwood shrinks more than heartwood when it dries. The less, the better if it is off center. I think if it was a band on a quarter sawn piece equal on either edge, you should be ok. Rift and flat sawn pieces would be the worst. Just think of the sapwood as a rubber band pulled tight and you should be able to better predict the movement if you are going to get it. ;D 8) 8) 8)
Manage 80 acre tree farm in central Missouri and Mesquite timber and about a gozillion saguaros in Arizona.

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