How to attach top

[Tar Heel]

I am making a jewlery box for a neighbor out of pine that came from her father's barn. It was rough looking stuff but after jointing and planing it down to 1/2" it looks pretty good. It is basically heart pine and you can smell the pine resin now that it has been planed. The box is completed (used my Leigh D4 dovetail jig for the first time) and I am trying to decide what to do about the top. I could just hinge a flat top to the box or cut an inch from the box and attach a top to that (that's what I want to do) and then hinge that assembly to the box. How concerned should I be with wood movement if I go with option two and how should the top be attached to allow for movement. The dimensions of the box are 14" X 7" so, allowing for a 1/2" overhang, the top would be 15 X 7 1/2. This wood is probably 75 to 100 years old and is as dry as a bone.

 

[dino drosas]

You should look at FWW, issue #197 (Apr 08. You really should have attached a top before your glue-up of the sides and had it float like the bottom to take care of wood movement; and at that time you band saw it off. At this point I think I would consider a hinged flat top directly to the box. Possible some sort of exposed hinge that leans to the rustic since the box is heart pine. My 2 cents!

 

[DaveO]

Stuart it isn't the current MC of the wood that you need to be so much concerned with but the EMC of the wood once it's equalized to the environment it will reside in. If you just hinge the slab top to the box you will probably get some cupping as the top of the lid reaches a different EMC than the bottom. The lack of air movement inside the box will be the cause of that. That can be combated by battens screwed to the underside of the top. At 7½" wide you won't get a gross amount of movement, but it still would be good to use elongated holes if you go with the screwed battens. According to the Shrinkulator a 7½" wide piece of Longleaf Pine will move about .13" with a 6% change in EMC (going from a very dry 6% to what you would expect wood to be at outside, 12%)
Another method would be to glue the top directly on to the box and cut off an inch or so of the box sides to create the lid. The side stock will help to keep the lid flat. Again at your width you shouldn't have a lot of movement unless the box will reside in an un-airconditioned home in south Florida. The problem with this method is the top overhang, you will have to attach ½" spacer blocks to the box sides to compensate for that and keep it square to the saw table.
Personally my favorite choice for box tops and bottoms is to capture them in dadoes in the sides, and then cut off the top. That way your panels will float, so wood movement shouldn't be of a concern, and you keep great grain continuity on the sides.

MTCW,
Dave

 

[Robert]

I just read that articler in FWW 197-Apr 08 while watching my daughter take her swimming lesson today. I liked the leather hinge for an old look. Have to go along with DaveO, it was quite humid at the YWCA and I did not notice any MC movement in any of those boxes.:gar-La;