Getting the Best Yield of Quartersawn Boards

      If you rotate the log during the sawing process, you can get more quartersawn wood and less rift-sawn. March 13, 2007

Question
Am I right that you can not get all of the true quartersawn lumber out of a log without turning it (or at least turning the quarters)? I keep seeing swingers telling how easy it is for them to QS a log, but I think they are taking much of the lumber as rift sawn lumber, and calling it quartersawn.

Forum Responses
(Sawing and Drying Forum)
From contributor S:
I would like to know also. I have looked at this for some time and found a couple of points that kind of tilt the results when I draw it out. First, every log is different, but assuming a good round log, would you want to take the heart out as a cant or beam? Depending on the size, I think I would. If the log was quartered, you lose this. If the log is quartered first and then sawn for quartered lumber, each board has a beveled edge on the inside. The beveled edge is pretty much waste; a swinger leaves the inside edge square. From what I can tell by drawing it out, the yield of rift versus quarter look to be about the same. This is not a mathematical certainty, just my best guess. The square edge and a chance to take out a good center cant puts me in the swing mill camp. Of course there are other more labor intensive ways of getting the cant out and quarter sawing the surrounding log.



From contributor V:
I'm far from being an expert, but for what it's worth with 100 hours on the mill: It depends a lot on the species and size of the log and what your market demands are. Also, there is the appearance of the finished wood. If it looks quarter sawn, it is. Don't get hung up on true quarter sawn unless it's for your own use or a particular market. The market dictates.

I "quarter" saw Douglas fir to get vertical grain lumber. It takes a fairly large log (40"+) to get good clear tight VG. Not much chance of rolling it around once the frame is around it. My market accepts up to about 60 degree slope of grain (rift sawn, if you will) toward the wide face, which still gives the appearance of VG. With that much leeway, I can "quarter" saw the whole log.

But the center is of little concern for VG grade lumber because of the knots and wider growth rings. But grade comes into play with beams because of a thing called FOHC (free of heart center). The most desirable beams and premium priced are FOHC, so that's where I try and take the taper out of the log. My understanding is that any board or beam that contains heart center will split. Boxing the heart center of smaller logs is a method of recovering more lumber with a so-so beam from the lower grade wood. I'd rather cut 2" X 4" and 2" x 6" from the center and sell them as construction wood.

I haven't cut any wood that requires you be dead on to get pattern, such as oak. That would be a different story and a learning curve for me. And it would also mostly mean smaller logs.



From contributor I:
When you are quartersawing on either mill, you are of course doing an approximate qsawn pattern. Some of the boards will be exactly 90 degrees to the growth rings, and some will tend toward rift sawn but will still grade as qsawn (i.e. 60-90 degrees). You will also end up with some rift sawn (30-60 deg) wood from the corners.

As you work across the log, the first boards will be rift sawn, then exactly qsawn, then back to rift again. This is slightly different to a bandmill where the log is quartered then the widest boards are cut out at exactly 90 degrees. After that, the boards get narrower and the angle drifts toward rift as the quarter log is sawn down.

However, neither mill will recover 100% quartersawn boards. The bandmill may be able to cut a few perfect wider boards if the log is big enough, but the later boards from each quarter will not be 90 degrees either. The swingblade is restricted to its 6/8/10" cut which can be a disadvantage, but the swingblade can qsaw a log with no extra work - it makes little difference to the operator if you cut an 8x1 or a 1x8 board from that location in the log.

The only way to get all qsawn boards is to radial saw, where the log is sawn up like slices of a pizza. This, however, is very wasteful, as the boards come out triangle shaped and have to be resawn/edged again. Although you have all prefect qsawn boards, half the log is in the waste pile.



From contributor N:
I was also interested in quartersawing some larger logs. I found a website with a few good illustrations. There are two different methods featured. One method for logs 16 to 19 inches in diameter and another method for logs over 20 inches. Both methods do require the log to be rotated 45 degrees at some point. I do not have the exact web address but the information was provided by the USDA, Forest Service, State and Private Forestry Division of Cooperative Forestry, Madison Wisconsin. Stanford J. Lunstrum is the technologist responsible for the information. I'm sure you can look at the diagrams and apply it to your swing mill.


From the original questioner:
So the answer is no, you can't get all the quarter sawn lumber without turning the log. That's exactly what I thought from watching swing mills work. I do QS some oak logs and I don't agree that there's 50% waste doing so with a bandmill. Some of the edging I get is cut to 5' lengths and sold/used as tomato stakes, etc. Also, I burn wood for heat, so there's another use that I don't consider waste. QS lumber brings enough higher price that I can accept more loss and time invested to get it too.


From contributor B:
You've got the right idea. I have a Wood-Mizer and when I'm in a quartersawing mood, I find a big red oak log - like 40 inches - and split it down the middle with a chainsaw. Then I stand the half on my mill and saw the top off so that I'm just on the edge of the section where the quartersawn boards will come rolling off. Then I remove the piece I've sawn off the top (with a forklift) and get to work. I saw down until the angle of the growth rings is around 70 degrees from perpendicular and then turn the big slab over to where the flat is resting on the sawmill bed. Then I do the same thing with the other end - saw off the top, remove, start sawing. When I start getting away from quartersawn, I bump the cant around until there's some right angle growth rings presenting themselves to the blade angle, shim up the cant, clamp it down and start sawing. There's some waste, no doubt - and you have to edge a whole mess of boards since there's a chainsaw-cut on one side and bark on the other. After a time, though, you've got a whole stack of genuine quartersawn oak. Then you do the other half! You just have to keep an eye on the grain and put the pieces on there and be prepared for some waste and time spent moving big pieces of wood around. The end result is real nice, though. Big wide quartersawn boards.

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