On Failure

When you build things that you hope will outlast you, it’s more than disappointing when they fall apart within a few years.  Sometimes it’s because of abuse, but more frequently it’s the result of a design flaw that only becomes apparent with time.

For example, about five years ago I built three footstools like this one:

At the time, I lacked the confidence (and the skills) to cut an angled mortise.  I had no tools for shaping round tenons, so I decided to try attaching the legs with lapped dovetails instead.

It seemed like a good idea at the time.

The problem is that dovetails are not designed to withstand the kind of force that would normally be applied to a stool.  Whereas a dovetail on a drawer tends to tighten when the drawer is pulled out, this dovetail loosened the more pressure was put on the joint.  Every time I stood on the stool, my weight was trying to force the joint apart.  Eventually, every leg on three stools (that’s twelve joints, for you mathematically impaired folks) came loose.

The stools were made of construction-grade pine, so I probably should have given them a proper cremation and started over with fresh materials.  But it’s hard to throw your own work away, even when it has failed.

So I decided to salvage the tops for rebuilt footstools, this time with proper joints.

I now own a matching taper reamer and tapered tenon cutter, so I cut new legs from some spare two-by southern yellow pine, shaved them down to octagons with my jack plane, and tapered the ends.

The tapered tenons (which look like upside-down ice cream cones with the tips cut off) fit into matching tapered holes, so every time I stand on the stool, my weight is tightening the joint.  It’s a trick that’s been used by chair makers for centuries.

Two of the original tops got cut into squares, and the third got cut into an oval.  Each got battens nailed to the bottoms to resist splitting.

The resulting stools look more spindly than the originals, but they are lighter and sturdier.  The splay of the legs (which the crummy photo above distorts) also makes them more stable in use than were the originals.

I am cautiously hopeful that the rebuilt stools will last longer than the first ones did.

This entry was posted in Musings, Wood and Woodwork and tagged , , , , . Bookmark the permalink.

2 Responses to On Failure

  1. Joshua Klein says:

    A timber framer friend of mine relayed to me the builder’s wisdom of “Build your first house for your enemy, your second house for your friend, and your third house for yourself.” Failure the first time is inevitable.

    Great job. I am sure they will fare better this go around.

  2. meeteyorites says:

    Great comment; Saint Theresa of Avila might chime in to that last comment, when she said to The Lord, “If this is how you treat your friends, it is no wonder You have so few of them!”

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