How much will lumber shrink during ai…
Jeffrey_P._Bengston | Posted in General Discussion on
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One of my co-workers is allowing my to harvest a big leaf maple from his property that he doesn’t want hampering the growth of his firs. The butt of the tree is riddled with burl and upon removing the bark, there is plentiful evidence of curl/quilt. Can’t wait to work that stuff. I’ll soon cut it down and have it milled into lumber.
What amount of shrinkage, all dimensions, should I expect during the air drying process? I’ll cut it soon before spring springs and water starts flowing up the tree and it gets too wet.
I’m going to cut logs to 6′ lengths since I don’t wan to break the back of my Toyota when I haul it. I’ll try to get some pics on here of it when I get around to it.
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Dried to 6% the radial shrinkage will be 3% and the tangential shrinkage will be 5.7%.
Somehow, though, I doubt that's the real info you're looking for.
Lee
*Total radial/tangential shrinkage is 3%/7%. Assuming the wood will dry to about 12%MC after air-drying you should expect to see 1.8%radial and 4.2% tangential shrinkage. (multiply the total shrinkage by {1-12/30} or 18/30)Jim Fuller
*Jeffrey:I assume most wood will typically shrink 8 to 10% when drying. For a 1 inch thick board, 8% is about 1/16 inch. When I mill lumber I cut it a “heavy” inch, or about 1-1/16”, from the log if I want a true 1” board when dry. Most of the time, even if I mill it 1 inch thick from the log I can still get a 3/4” board after planning when dry. But I may not be able to get a 13/16” or 7/8”. So consider what you want in final dry form and adjust from there. I know a guy who told the sawmill to cut his log into 3/4” boards. They did, and he ended up with a lot of half inch dry oak a year later. A couple of other things to consider. First, how will the logs be milled? My first log was milled by a guy with a portable bandsaw mill. Bandsaw mills are nice, but some have a tendency to allow the blade to wander up and down while milling. So you may ask for 1” boards and end up with stuff that’s “about” 1” thick, but maybe only 7/8” in some spots, and 1-1/8” in others. I recently started milling my own logs with a chainsaw mill. It’s slow, but it gives me a nice flat surface and a consistent thickness. If you go with a bandsaw operator, watch the surface of the boards coming off the mill and adjust accordingly. The second thing to consider is the length to cut the logs. As the boards dry they will typically split on the ends. If I wanted a 6’ final length I would cut the logs 6’-6” and figure to lose 3” off both ends. The longer you can cut the logs the less waste due to splitting. And if your truck can’t handle the weight, consider renting or borrowing a trailer. Better to pull the weight with your truck and let the trailer carry the weight. Then you could get longer logs. And maybe all in one trip.Dave
*With regard to the 6' length, check your mill and see if they will saw a log that short. If a mill has to reset the dogs to mill the log they may not take it or they may charge extra. I don't think that band mills have this problem.BJ
*If you go with a band saw operator, buy him/her some new blades and request that they be changed when needed.
*Thank you all for your input! I'd like to end up with a finished, after drying and surfacing, thickness of at least 1". So I 'll probably have it milled to 1 1/2" to be safe.I have a friend who has a top end WoodMizer who will happily mill it for free. That's nice. I once had a job in which we milled all our structural lumber, doug fir and some pine. I ran the Mobile Dimension mill. It was a portable circular mill. It was a blast to run. It had a 5/16" kerf on the head saw and the edger blades were 1/4". One nice thing about it was that you could 1/4 saw just about every board that came off it. Our shrinkage with doug fir that had been on the ground for a few months was never really more than 1/8" or 1/4". The timber was Forest Service marked for us to thin on our leased USFS land. We got some nice logs out of it. A few logs yeilded cvg 1x12s, and that was limited by the saw. Enough rambling of days past. I'll try for some pics of that on here.
*4/4 lumber is usually sawn at 1 1/8".Don't waste the wood unless you want thicker lumber.Lee
*Shrinkage varies greatly from species to species. Total shrinkage can be as low as 3% and as high as 13%. Big leaf maple has fairly low shrinkage as I posted above.Jim Fuller
Dry time for logsi
i was wondering if anyone can tell me how much a log will shrink lengthwise. I am building a new house and am using logs for support beams, but am having a hard time finding dried logs so was looking into fresh cut ones. Thanks for your help.
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