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.
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.
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.
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.
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!
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?
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.
The pith may not be centered and there could be taper in the log that will not allow more than 3 beams per log.
Any sapwood, especially if off center or only on one edge will greatly increase curvature with drying. :(
Don't forget to account for blade kirf
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.
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?
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)