Building to Tolerance

Tolerance is more than an old, old wooden ship that was used during the Civil War era. A quick search defines tolerance as “an allowable amount of variation of a specified quantity, especially in the dimensions of a machine or part.” When building anything one must consider the tolerances available in construction; being 1/8th of an inch off will generally not make a difference while framing a house, but being 1/8th off on a jewelry box could ruin it.

Before starting any project the tolerance should be established. Last week I built a couch out of reclaimed pallets. I don’t generally like working with pallets, the material is only vaguely square and often has twists or bends, it also is rarely cut to any standard size. Because of the rough nature of the material and the timeframe I had for the actual construction I knew the tolerances would be fairly loose.

I used a reciprocating saw to cut half-laps into the runners (the thick boards that go under the pallet) and a large angle gauge to set the rake of the legs and back. Deck screws and corner braces held the joints secure. Keeping the tolerance in mind these joints are not very tight, and because the runners had slightly different spacing I had to use shims of 1/2 inch and 3/4 inch mdf to fill gaps. The legs are made of 2x12 lumber from the home store, with a shallow taper cut to lean the couch back slightly.

I referenced a chart of common furniture dimensions from a Core77 article to determine the angles used in this couch, though I kept the seat far more level than recommended at 3 degrees tilt rather than the 12 degrees specified.

This couch has proven popular with my partner and our dogs:


I used deck screws because I anticipate this couch going outdoors one day, after I make a more refined piece of furniture (with tighter tolerances).

See how I made it here: