Calibrating a Carpenter's Level
Keith Mc
Calibrating a Carpenter's Level
While attempting to level a lathe, I was concerned with my cheap carpenter's
level calibration, and decided to check it. (After all, you can only control up to
what you can measure... :-)
You can correct a carpenter's level calibration, with the following procedure:
1) Place a nail in the wall. (Garage studs and unfinished basement studs are
good for this procedure, to keep peace with the spouse... ;-)
2) Lay level horizontally against the wall, with one end resting on the nail.
3) Rotate the level till the bubble indicates level, and draw a line on the wall along the
bottom edge.
4) Flip the level end for end, re-level, and re-mark.
... IF the lines are the same, you are done. BUT... if you find you now have two
diverging lines, your level is out of calibration and needs correcting. (Continue...)
5) Mark a point midway between these lines.
Bisection can be done with compass and straightedge, or with only a ruler.
Compass method:
(Google "How to bisect an angle with a compass and straightedge".
Lots of examples out there... It's good to know, and great to practice...)
Ruler method:
--- Using the ruler, mark the same distance from the nail on each line.
--- Find the midpoint between these two points with the ruler.
--- Draw a line from the nail through that line, thus bisecting the two lines.
(This averages the two readings, giving you a true level line.)
6) Align the level resting on the nail to this new line.
7) Finally, without moving the level, adjust the bubble's holder to indicate level.
Note that this method works even with a series of vertical studs, vs a solid wall.
This technique can also be used to correct all axes of a multiaxis level, one at a time.
I hope this helps someone...
- Keith Mc.