How dry should wood be to build work benches out of? I am planning on building a new bench, tool storage and shop cabinets. Last fall I bought a load of rough cut 4/4 Hard Maple shorts from a sawyer. It had been air dried for about six months. I have it sticker in my basement shop. I just tested a sample for moisture and it registered lass than 8% on the out side. I planed off the rough and tested it again. It measured 14%. I cut it in half and the middle measures 16%.
How dry should wood be for building bench tops? Does it need to be as dry as it would be for furniture? I am thinking of making the tops 3 inches thick. If the wood it to wet to start with it will take a long time to dry out after it is glued up.
Thanks for your insights on this,
Bob T.
Replies
What's the difference between a workbench and fine furniture? In my view, the only difference is in appearance. All else is treated equally.
Chris @ flairwoodworks
- Success is not the key to happines. Happiness is the key to success. If you love what you are doing, you will be successful. - Albert Schweitzer
Depends of course on your climate and how the pile is stacked. But shooting from the hip I'd say to check again in 6 months time. If you're impatient you can always buy KD lumber and use the maple for something else next year...
David Ring
http://www.touchwood.co.il/?id=1&lang=e
David,
Does it make any sense to dry the wood drier than the woodshop environment? Of course seasonal movement will still occur so it seems like construction technique comes into play here.
Regards,Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
There's no point at all in getting it lower than its intended environment. Maybe it'll never go below 10%. Doesn't matter. (There's another thread running now asking what's the point in kiln drying to 8% when it's going to find equilibrium at 12% anyway...That's another question that involves the economics of kiln drying among other things) Once the wood for his bench has stabilized it's ready to use. Right now the differential he sees between the drier outer surface and the wetter inside shows that it has not stabilized yet.
If you monitor the drying progress you'll see that the initial drop from say 30% down to 15% is quite rapid. Then the process slows down so that going from 15% down to 10% may take many months in the air. Cracks and checking are caused by the outside drying too fast in relation to the inner layer. In kiln drying it is critical to follow the appropriate schedules of temp and humidity to avoid getting defects. In air drying you don't have much control, but letting nature take her course means also finding lots of patience...
regards, David Ring
http://www.touchwood.co.il/?id=1&lang=e
David,
This is most likely going to be a bit off the wall but I wonder why, outside of the physical aspects, there hasn't been a microwave type of kiln? My understanding is that the heat goes deeply inside the material and I would think that it would work, perhaps better than existing kiln drying methods..............
Just curious,
Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
Edited 3/10/2008 12:06 pm ET by KiddervilleAcres
Aside from the massive power requirements I think casehardening would be a real problem as you cooked the interior of the wood.
Napie & Steve,
Might want to check this out: http://www.p2pays.org/ref/36/35149.pdf
Regards,Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
That's not a microwave kiln. That's a microwave pretreatment process to alter the structure of the wood so that the follow-on kilning process is made more efficient. In effect, the process "loosens" the water that's in the wood so that it can be driven out more quickly without damage. But it's still kilned afterwards--the advantage is that the kiln schedule is shortened.
It's not clear from that snippet, but I would guess that the microwave pretreatment is not performed on full kiln loads of lumber at one time (which means that the cost of the microwave equipment is much less than it would be if you were to try to build a treatment chamber as big as a kiln).
-Steve
A microwave kiln would only make sense if the limiting factor were getting the heat to the middle of the wood. But that's not the limiting factor--the limiting factor is how quickly you can get the moisture out. Think of it this way: In a conventional kiln, the center of a piece of wood reaches thermal equilibrium with the outside within an hour or two. But getting the moisture out (without destroying the wood) takes days or weeks. So speeding that initial heating from a couple of hours to, say, fifteen minutes, doesn't really buy you much--it still takes days or weeks to get the water out.
A microwave kiln would also be $$$$.
-Steve
Bob,
Oh but they exist! Microwave kilns that is.. there is one I think in West Virginnia that will dry timbers overnight. big giant timberframe timbers..
frenchy,
I was wondering about it as I found they are used for pottery and crafts too. I'll have to find the one you refer to.
Here's an add for one: http://www.industrialmicrowaveservices.com/dryer.html
Regards,
Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
Edited 3/10/2008 12:30 pm ET by KiddervilleAcres
Bob, you're not off the wall and there is microwave drying. My son bought Douglas Fir timbers for his house about 5 years ago - cross sections of 8x10's, 8x12's and so on. They were all dried in a microwave kiln in Washington state (I think the firm was Timbercraft Post and Beam), and they are beautiful and check-free today. But the cost is through-the-roof expensive. It's not yet an economical alternative to the common energy sources used in kiln drying. Whoever figures out a way to make competitive microwave kilns will make a fortune.David Ring
http://www.touchwood.co.il/?id=1&lang=e
David,
I have done some more searching and I find that microwave kiln drying is being done in Canada and is slowly making inroads into the U.S. Not sure about other parts of the world but I have found that some German companies are onto it too.
Lots of good stuff; less checking, ability to spot or direct treatment; similar qualities to air drying, etc. Seems it started with pre-treatment but is progressing further to full scale drying.
Interesting stuff, Eh. Guess it's just a matter of time.
Regards,Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
Why not just take some old microwaves apart and aim them at your wood? That's what Red Green would do!Chris @ flairwoodworks
- Success is not the key to happines. Happiness is the key to success. If you love what you are doing, you will be successful. - Albert Schweitzer
Bob,
After you are happy with the moisture content of the wood you will be using, be aware that it will still expand and contract through the course of the seasons no matter how dry you start with.
Making an allowance for the wood to move can be accomplished in many ways. If you cap the end of your bench with a tongue and grooved component, let the tongue and groove be a "living" joint by gluing only the first couple inches and bolting with recessed lags. Let one lag be a tight fit (the end you glue) and make the holes for the others elongated. Pop the lags in the center of those elongated holes.
I live in the great lakes region, and my bench top moves through the course of the year almost a full 1/16".
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