Measure Twice, Cut Once

Leg mortise drilled out

Angles are hard. Especially if you don’t have a protractor.

Tonight, I realized I’d made my First Major Blunder on the bench build. From Chris Schwarz plan for the Nicholson bench, I’m using legs that sit at a twenty degree angle off vertical, seventy to the floor. Well, I thought I was. I don’t currently have a protractor, even a dumb cheap one, so when I need an angle, I lay it out on my bench. I still remember my trig from high school and I’ve got a pretty good square, so it’s pretty easy to just lay out the line off my current bench side and then set up a bevel gauge to match.

Leg mortise cleaned up

A seventy degree angle happens to be really close to a 4 in 11 run. That is, measure over 4 units, then up 11 units, and you’ve got the seventy / twenty pairing. I set my bevel gauge, locked it down tight, and saved the line on my bench just in case. I cut the ends of the legs and the apron support using the bevel gauge and all was happy with the world.

Except, somehow, I measured over 5 and up 11. So all my angles are closer to the 65 / 25 pairing. So my legs lean a little more than five degrees more than they should, and they end up being about 3/4 of an inch short, relative to the floor. Happily, when I marked the width of the apron rabbet on the leg, I used the actual apron, not a measurement, so that all still fits.

After playing with it for a bit, I’ve decided to just live with the slightly shorter bench. If it really bugs me, I figure shimming up 3/4 of an inch shouldn’t be too rough. It does mean that I’ve got to refigure how long the vise chop is going to need to be in square wood, but I’ve got 7′ of 8/4 Ash. I’m sure I can find a chop in there somewhere.

So after deciding to live with it, I trimmed up the saw marks and a “squared” up the bottom of the legs to get everything happy at 25 / 65.

Lessons learned:

  1. When measuring angles out by hand, triple check your work. Ideally walk away and come back.
  2. Get a damn protractor
  3. Trimming end grain sliced at 20 degrees is a lot like trimming pure end grain. It’s tough on a blade. Make sure it’s sharp sharp sharp sharp and take it slow.