How long to acclimate wood before final cuts?

[Craig Parker]

Hi All,
I making a torsion box assembly table ala Marc Spagnuolo's video and jointed/planed the edges of four 6' 2x4s yesterday. When I checked them this morning each was not flat anymore. So, the question is, how long do I wait to j/p the edges again without risk of moving again? Thanks.

Craig

[Tim Allaire]

bout 2wks in your shop

[Richard M. Wolfe]

It depends on the humidity of the shop and the humidity of the wood. Tim's reply of two weeks is the general rule of thumb. You might flip the lumber daily for three or four days and see what happens, if it's convenient for you. I had a fairly wide piece of ash that had been air dried that I planed and laid on the table. When I came back the next day it was bowed up on the ends by a little. I turned it over and the next day had the ends had bowed up again, but by much less. Flipped it again and after about the fifth flip it stayed flat. That was just an experiment of sorts; had I wanted it to acclimate faster I would have put stickers under it for airflow around the whole board.

[John Keeton]

Craig, I haven't seen the video, but if you are using borg construction lumber, most of that is fast growth "farm" lumber, and is notorious for doing some crazy stuff. It may well move again after it is planed. Do Marc's plans permit the use of mdf? It would be considerably more stable.

[Scott Hildenbrand]

Reminds me of that lengthy discussion I spurred when I brought up torsion boxes.

http://www.sawmillcreek.org/showthread.php?t=121931

2x4's will spring any which way, no matter how much you mill them or how long you wait..

Anyway, assuming you're setting up an absolutely flat surface to work on. You'd be better off jointing the 2xs and using them as the flats right away as they will end up shifting over night. Get the MDF laid over them and build up your grid right after you joint and level them and you should be fine.

[Faust M. Ruggiero]

Craig,
1/2" MDF is all you need for the egg crate inside a torsion box. It's dead flat and cuts true and should not move at all under normal conditions. It's a bit heavy but is available in a "light weight" version. When the "box" is finished, wrap it with some 1/2" thick hardwood to make it look pretty.
fmr

[Paul Johnstone]

Hi All,
I making a torsion box assembly table ala Marc Spagnuolo's video and jointed/planed the edges of four 6' 2x4s yesterday. When I checked them this morning each was not flat anymore. So, the question is, how long do I wait to j/p the edges again without risk of moving again? Thanks.

Craig

I'm not sure the 2 x 4 s will ever stop moving.
Remember, they are not kiln dried to the low moisture level that furniture grade hardwood is. They are fine for framing a house, but not for something that needs to be dead flat.

Why not use plywood instead of 2 x 4.. It will be much more stable.

[Scott Hildenbrand]

He's using the 2x4s as a flat surface to start building the box on.. Assuming he's following Marc's video. They're not for the inner portion.

[John Harden]

He's using the 2x4s as a flat surface to start building the box on.. Assuming he's following Marc's video. They're not for the inner portion.

I've never seen the video, but if he's looking for a very flat, large surface to work on, I agree with the idea of not using 2X4's. Even kiln dried studs are still made from pretty crappy wood and will likely move again and again.

If he needs straight, flat, rigid beams, better to make them out of MDF. Just make an I beam, minus the lower cross part of the I. Essentially a T beam. The top of the T is your flat surface and the lower portion, which is glued and screwed (or brad nailed) to the top provides the beam strength to keep it flat under load.

You then toss a piece of MDF on top of it as your work surface to build your torsion box.

The T beams are quick and cheap to build and just as easy to store or cut up and toss out once you're done with them. They will also support gobs of weight without flexing.

That's my .02

Regards,

John

[Scott Hildenbrand]

Pretty valuable two cents if you ask me.. Should charge a quarter for it at least.

[Glenn Vaughn]

As I understand it wood movement is related to humidity changes. I have been tracking the weather here in Colorado (well actually in my yard) since early August this year. I have 2 sensors that report humidity - one outdoor and one indoor. The information is a bit suprising; the common belief here in Colorado is we have very low humidity but the graphs I have show that we actually have periods of low and periods of high humidity every day. Outdoors it is usually a very large difference between the low and the high for a given day./ Indoors is a different matter; during the hot months the indoor spread is about 20 - 40 percentage points. During the colder months (when the windows are kept closed) it is much smaller (November had a couple of days where it was 10 percentage points - the rest of the month is about 5 percentage points).

If you are curious as to the graphs the can be seen at http://www.dawiz.net/weather/allmonths.html.

I need to get a sensor for the garageand see what it is there - might be a good place for acclimating wood.

Glenn

[Craig Parker]

Hi All,
Thanks for all the ideas. I think I will re-j/p the 2x4s and just work fast as Scott suggested although I think the next time I build a torsion box I will use lighter material and skins thinner.

Craig