I am now on page 32 of the 53 pages in this topic on the site and found myself wondering this question.
If I was cutting up logs to make timbers for a square/rectangle log home or even a timber frame home and was milling and stacking my timbers correctly and some bow before use, could you stack/sticker the bowed timbers so as to straiten them back out? Would they straiten back out after some time and some drying?
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Likely not..
Since at times people will soak wood in order to bend it, could you re moisten the wood in a trough and then put under pressure in a stack in attempt to straiten. I wonder because if I was milling out for said log building and half of your wood is bowed what would be the answer, get more wood? The type of timbers would be red pine 6x8 , 8x12 and at least 12' to 36' My hopes where to build a rectangular log on log home, with a dovetail, out of the stand of red pine I own. I was maybe thinking of storing the milled beams indoors or under a lean to, till I had enough made to assemble the home. Or even better yet, pre build the home in a pole barn and reassemble on a foundation at site.
you might be able to do it with steam.
In my opinion there is no practical way to straighten bowed timbers to build a cabin by soaking, steaming and fancy stickering.
There are other ways to cut straight timbers out of fair logs.
1. Cut in 1" increments and turn after every cut. This will keep your timber true as you get it down to your target size.
2. You could cut over size and then resaw after they dry. Make your 6" x 8" say 7" x 9" or larger, then resaw to 6" x 8" after it has dried for a while.
3. You'll need 1x sheathing and flooring for your cabin. Make this out of the logs that will not make a straight timber.
Anything that is left after this will get you a head start on next year's firewood. ;D
Green wood has roughly half the stiffness of dry wood. That means you could take a bowed timber and weight it until it was straight (but don't expect it's own weight to be enough ;D). When it dried it would remain straight -- unless it got wet again. Then it would revert to where it wanted to be in the first place.
When people bend dry wood with steam, it's the heat that makes the wood more flexible, not the moisture.
Do larger timbers that are stacked and stickered properly typically bow very much? My 8x8s and larger didn't bow much at all. The 3x5s bowed a lot, but not the larger stuff.
My experience with Red Pine on the east coast is that it is just gnarly. I have custom cut, dried, and planed it on occasion and I don't recommend using it for finish or dry applications. I do however love making what we call "live log" Log home timbers with it. Super camp(3 season structure) material. Saw it flat top and bottom leave the two sides live just hand peel the bark makes a killer looking rustic cabin. I have even re-tooled our Pinheiro planer to put a single tongue and groove system into these for a customer. We did that all green though. It also makes great dock cribbing material in the 6x6 dimension. As far as pilling square timber and sticking it to keep it relatively straight we use horizontal Stickers of the same thickness (3/4" and the width varies from 1" to 1-1/2") 2 feet on center and we use vertical "T" stickers at the ends of the courses of timbers. When you pile them up just make sure the stickers in each course are lined up with the course above/below. It will help keep them fairly uniform as they air dry. It won't help much if the wood was stressed/compressed as a log. Like I said the red pine here is a tough bugger. Good luck!
Edit: Just re-read the post. No good way that I know of to straighten material after it has gotten bowed. If we're using it for cabin stock the closest we come to it is to cut 16' timbers in half. Not the best answer I know, but its all I got. Again good luck.
I agree that there is no practical way to straighten timbers. Theoretically, if you could get the moisture content back up, force it into position, and properly kiln dry it.... but this would not be practical.
There are quite a number of things that cause a timber to bow, crown, twist as it's drying. It can be inherent in the growth of the grain itself- if it's spiral grain, if there is reaction wood, or multiple hearts. It Could also be how it's cut. A boxed heart timber may have more equal stress on all sides, where as a free of heart timber will not dry symmetrically. Then there is the issue of tension in the outer fibers of the beam. I just read about this and have found it to be true in actual experience. You may have a board or timber that is fairly straight and stable, but as soon as you start cutting off one side, it starts to bow. This is because the outer fibers dried quickly, attempting to shrink, but the green core would not allow for the shrinkage, thus tension was created in the outer fibers of the timber. So when you cut one side, you are relieving tension on that side.
In any case, if you want to work with dry timbers, as has been suggested, cut them oversize, and after they dry, then resize them. It's twice the work, but without a kiln, what choice do you have? I have that same situation right now with reclaim. About 30-40 percent of my timbers have twist, bow, or crown. They are dry after 116 years. So I'm going to straighten them with my mill and beam planer. Honestly I don't know how well the bandsaw blade will track in a bowed timber, whether it will cut flat to the bed, or try to follow the grain. If it starts to dive or climb, I'll fall back on the planer to correct it.
Thank you all very much for your knowledge, Gentlemen, and am just full of questions before I begin my future in milling. I will be up in northern WI. this next week taking a dimensional lumber grading course in an attempt to also grow my understanding of the process. No thing like knowing to much before hand. I'm green now :o but will hopefully change my own MC with time. ;)