I purchased some white oak from a local mill about 2-3 months ago.
The wood had been stickered and covered outdoors. The guy I bought
the wood from claimed that it was aged just about the minimum
necessary for use. I stored the wood in my garage (a very stable
environmet)for 2-3 months before use.
The other day, I jointed then planed the wood from about 1" down to
1/2". The boards were perfectly flat. Within 24 hours almost all the
boards had warped --not drastically, but certainly noticeably to the
eye. I was surprised at the amount of movement in just 24 hours. Is
it a simple conclusion that this wood is not dried enough? Could I
have released tension in the wood by planing it so much so quickly?
Are moisture meters an essential tool when most of one's supply comes
from a local rough cut mill?
You really need to plane both sides equally. The center of the board has
more moisture than the outside surfaces. You can try another board, or you
can paint the ends of the boards with white glue or wax and let them dry for
another year. They really need to be under 10% moisture (6 is better) to
have stable wood.
On 30 Nov 2004 16:04:42 -0800, email@example.com (Doug) wrote:
What's the air humidity in your garage, and did you sticker them ?
Pretzel city. If they were quarter sawn then you'd barely notice it,
but if these were the usual flatsawn stock, then taking half the
thickness away is going to cup them like crazy. Do you have much
twist in there ? Just how bad is this movement ?
There's a difference between "dry" and "dried enough". You can kiln
it and get it down to a low MC in no time at all. But this doesn't
make the wood stable - if you expose it to some more moisture then it
will absorb it and the MC shoots up again. It can easily show "reverse
case hardening" behaviour in this state. If it was originally
air-dried, then it's unlikely to show case hardening though.
If you want stable timber, then you have to wait a few years. Let the
timber go through a few seasonal cycles - each one will become slower
and less severe for movement, even though the MC still varies. I
wouldn't use air-dried oak after only one season, even if the MC was
low on that day.
If you have some full-thickness ends to play with, do a tuning fork
test. Take a long narow slice, saw a groove down the inside to leave
two long legs. See which way they move.
I don't have much use for a moisture meter - I prefer an air
hygrometer and waiting for equilibrium. Unless you spend a lot on a
meter, they're just not that accurate. Buying timber of unknown MC
though, that's a good time to have one.
I'd still rather know what the drying history has been so far. I'm
rarely buying timber to use immediately, so a summer in my own racks
will get the MC down pretty well anyway.
What is "warp" to you? Wood behaves predictably when drying, it bends
toward the formerly wet, so you should be able to pinpoint your problem
quickly, rather than sift through speculation.
http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr117.pdf for air drying.
http://www.fpl.fs.fed.us/documnts/usda/ah531.pdf for storing, admittedly on
industrial scale, but informative.
24 hours? Ha, try minutes..This is the nature of woodworking. Even the best
of air dried, kiln dried woods have a mind of their own. As suggested,
planing down equally from both sides helps. You might also consider
roughing out your stock, let sit several days and then machine to final
size. Moisture meters are cheap, pick one up.
Radial Arm Saw Forum: http://forums.delphiforums.com/woodbutcher/start
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.