A table is only as good as its parts, and if those parts aren't square, then neither is the table. In the rush and excitement of nearing the completion of your hand made table, it's easy to overlook the importance of keep it all square and straight. Taking steps to ensure everything will go together squarely is a lot easier than brainstorming how to fix it afterward. Using just a few tools and investing a little more time while gluing things up, can mean total success.
Things You'll Need
Sliding combination square
Square the Table Base
Assemble the legs and aprons of the the table base, and place them in your clamps. Make sure to clamp everything together on a flat level surface, like a dedicated assembly table or workbench.
Measure across the table base diagonally, by hooking the end of your tape measure on the outside corner of the table base and measure to the opposite outside corner. Write down this measurement. Now measure across the table base from the other diagonal. Write this measurement down. If there is any difference between the two measurements, this is the amount that the table base is out of square.
Bring the table base into square by slightly tightening or loosening the clamps. You want to tighten the side that has the shorter measurement, or loosen the side that has the longer measurement. Sometimes, it's necessary to do a bit of both. Take diagonal measurements again to see if the base is square.
Squaring the Top
Measure the table top, (before attaching it to the base) to check for square. Measure the length from both ends, then measure the width from both ends. If the top is out of square, it will show in these measurements.
Double check your measurements, using a sliding combination square and place it on the corner of the table top. If the side is square with the end, then the square will rest against them without any gaps. If it's out of square, there will be noticeable gaps.
Correct the table top by placing it in a wooden vice on a workbench and shave the ends that are out of square with a handplane, taking very light cuts. Check the work often with your sliding square. Another way to square the table top is to use a cross cut sled and a table saw. Place the top in the sled and cut off the amount that is excess and out of square. Check each cut with the sliding square.
To avoid the confusion of numbers and fractions, you can measure the able base using a long strip of hardwood approximately 1/4 inch thick, 3/4 inch wide and a few inches longer than the diagonal measurement of the table base. Simply butt one end of the stick on the inside corner of the base and mark the opposite diagonal inside corner location with a pencil on the stick. Then check the mark the other corner's diagonal measurements and check to see if there is any difference. Measuring without numbers!