I am always pleased to hear when someone receives a piece of furniture from me and they are amazed at how well built it is. (Sorry, I know it sounds like I am patting myself on the back but, please read on). However what this tells me is that most people have never really seen properly built furniture. This is not really our fault. Most of us have experienced furniture the Ikea way, screws for joints and particle board for the structure. It reminds me of how there was a time when the average person could buy a used vehicle, look it over, and actually know what to look for to see if it where in good shape. There has alway seemed to be a lose of knowledge as society "advances".
So let me get to the point of this entry. I just recently had a customers who had previously bought a table from a "craftsman" and it was cracking down the center of the table very badly. I was unfortunately unable to give her a simple fix. It was constructed inproperly from the beginning. Let me show one way you should expect a solid wood table top to look from the under side when it is properly constructed. This photo is the bottom of a typical table top I build in my shop.
Notice the little blocks attached to the bottom of the top that are then slotted into the rails. Notice that the rails create a frame work. Why go to all this effort, can't I just screw the top to the base and legs? Its true, I could, and some have tried (as in the case of the "craftsman" I perviously spoke of).
Now here is why you shouldn't... First you need to understand that wood moves with moisture change from summer to winter. It moves a lot, as much a 1/8" per foot, depending on wood type. Thats 3/8" for a three foot wide table. Now look closely and you can see that the slot that the block is slotted into is oversized. This allows the top to "float"on the framework under the table top while staying in place and flat. If you where to screw the top on in a fixed position (which might seem the obvious thing to do) then the top will start to split down the length of the table as it expands and contract through out the year. I know, scary.
So bottom line. Buy well made furniture from a craftsman that not only has the tools to "work wood" but also understands wood and how to properly build with it. Century's of tried and true construction methods can't be ignored when using this ancient building material.