The Strength of a Chair Comes from Imperfection
If you’ve ever used a hand-cut rasp or a hand-filed saw you know how their tiny imperfections from handwork make the tool cut smoother. When it comes to making chairs, the small handmade imperfections are what give it its strength.
If you build a lot of casework, I am sure you are grunting in displeasure. Accuracy makes all your pieces go together easily and tightly, right?
Well in chairmaking, that same sort of accuracy is undesirable. Here’s why:
Years ago I repaired a factory-made Windsor chair for a family member. The chair had fallen to pieces. So I cleaned off all the old glue and reassembled the chair. It went together perfectly and with great ease – all the spindles dropped nicely into their mortises.
Within five years, the chair was coming apart again.
Part of the problem with perfect factory chairs is that they don’t have any tension in them. All the parts line up (thank you, CNC) and go together with ease.
When a flawed human makes a chair, every angle of every joint is off by a half degree or more. These imperfections push the seat, arms and crest rail in random directions. As a result, every handmade chair has to be coaxed together with a mallet.
Additionally, many chairmakers introduce some tension to the undercarriage by making all the stretchers about 1/8” longer than they should be. This forces the feet to push away from the perimeter of the seat. And it racks the heck out of the undercarriage, making it incredibly robust.
All of these facts should be a great comfort for the beginning chairmaker. When you are drilling your holes, being a little off will make it harder to assemble the chair. But it will also make the chair harder to take apart.
One word of advice: Don’t try to be inaccurate. You’ll either be dead-on balls or so inaccurate that the chair won’t go together (been there). Just try to do your best. Your humanity will do the rest.
— Christopher Schwarz