Wood Movement in Small Projects

[Glen Blanchard]

As I understand it, wood moves (in the correct climate) as a percentage of its cross-grain length. Of course, to allow for this movement when attaching a table top to its legs, hardware specific to this task is used (figure eights, etc.).

Here is my question.....Should one still allow for wood movement in a scaled down version of a similar item. To be more specific, I have a small chest that I am wanting to rest on legs made specifically for the chest. The bottom of the chest (its footprint) measures 6" x 9". I'm wondering if such a small project should employ something like figure eights, or if (due to the diminutive size) merely placing wood cleats would suffice.

I'd love to hear some opinions. Thanks in advance.

[Dan Barr]

The wood movement for White oak 6 inches wide comes out to be just a hair over 1/32". (0.516 16ths; I'm assuming a 3% annual moisture content change)

if the bottom is dadoed into the side panels, and you left a little space (1/32") in the dado for width movement, then dont worry about it.

if however, you just glued a flat panel to the bottom without any joinery, then eventually, the bottom might seperate from the panels or defeat the corner joinery on the panels. it will probably take 20 years for it to happen, but it can happen.

here is a thread for calculating wood movement.

http://www.sawmillcreek.org/showthre...d=5960&t=67957

hope this helps

v/r

dan

[Todd Jensen]

In my personal opinion, simple joinery(cleats as mentioned) and glue should hold up for a lifetime in a project this small. I made a rudimentary box for my wife our first Christmas that was that size(6x9) out of Cherry and Maple, all of my joints were just mitered and glued, and it still sits on her dresser 6 years later looking and functioning exactly as it did when new. While I agree wood movement is a factor to be considered when working with wood, I am not of the camp that uses formulas everytime I build something. Nothing against those that do, but for me it is a little overkill. I have a desk in my office built by my great-grandfather over 70 years ago, solid wood with 7 box drawers, and its bullet-proof. Large dining tables, etc may be a different story but for most projects I believe you'd be surprised how well basic joinery and glue handles wood movement. Of course, JMO.

[Dan Barr]

I'm not the type for the formuals for every project either. But i did see two small boxes the other day that had their bottoms split and seperating because of wood movement. the maker made the bottoms without any regard to movement and the boxes were about 10-15 years old. He had placed in each box a sheet of paper with his statement about the boxes quality saying that this box is of the highest quality, blah blah blah. These statements were printed in dot matrix. Thats how I am dating the boxes at 10-15 yrs.

these boxes were smaller too. about 4" x 6" each.

v/r

dan

[Todd Jensen]

Thats good to know Dan. It sounds like I'm going to have to start giving wood movement more credence. I really like how he put the notes in about quality. Thats pretty funny. I've always felt work should speak for itself. Anyways, thanks for the info, I'd have never guessed that cracking would occur in something that size - it almost makes me wonder if they were stuck near a heater or something wierd. Very interesting.