Requested to saw some beams for a builder in our area. He needs 12 beams 6"x8"x14' with a 2" radia/arch cut on the bottom side. Material will be hemlock. This is my first attempt at such and I have a few questions and would appreciate your input.
Can these beams be installed green?
Will the 2" relief on the bottom cause tension to either build or release? And....what is the best way to remove material on the bottom side to give the arched appearance?
Can't help on the green install question but the best tool for cutting the relief would be a mafell hand held bandsaw. But they run $6,000ish.
Or put the beams on roller skates and use a $1200 Jet or similar bandsaw.
Anybody remember their chord math, what is the radius? A swingset over the bandmill could swing the timber through a fixed head... if the swing point isn't a mile high.
Check out the bandsaw that @tule peak timber (https://forestryforum.com/board/index.php?action=profile;u=25190) shows in some of his photos, not sure the brand, but perhaps you could adapt a small hobby bandsaw to work upside down like that? Laying out the line will take some figuring, but it's do-able for sure.
Tule has a Mafell...
A Pratzi Beam cutter (short chainsaw bar that is attached to a worm drive circular saw) can be used to cut radiuses in beams. It's not as fine of a kerf as a band saw, but works ok.
Draw out your arc and creative use of toe boards at each end... ;)
Tim, from Moon Hill Farm in Maine, did it on his band mill but slowly making the cut and raise and lower the band while traveling down the log.
show here:
Curves - YouTube (https://youtu.be/I6NBYTBFDgM)
Jim Rogers
I had to do some circlehead windows in a log wall and used the prazi facing 90° to the cutline and swinging on a wooden pivot arm to do the final chainsaw cleanup, it smoothed it out a bit more.
The next one was a table large enough to push what I needed through a shop bandsaw. I've seen guys put skates on a shop bandsaw, support the beam and push the saw through the work.
If you cut away 2" from the 8" timber you'll have a 6x6 when done. If it were me doing it, I'd try and center the pith of the timber in the 6x6. That way what's left will be a boxed heart timber.
There is no way to know what the tension or stress is in that timber until you cut it. You'll have to "read" the timber while milling it to see if it moves as you cut it. And if it does try and release the stress/tension evenly.
Jim Rogers