[Crispndry] found he needed a laser level, but didn’t want to spend a few hundred dollars on a tool he might only get a few uses out of… So he decided to build one himself.
If you’re not familiar, a laser level projects a laser beam, level to wherever you put it — it works by having a very precise gimbal assembly that keeps the laser perpendicular to the force of gravity. To build his, [Crispndry] needed a highly precise bearing assembly in order to build his gimbal — what better to use one out of a hard drive?
He used the main bearing from the platter for one axis, and the bearing from the read and write arm for the second axis. A square tube of aluminum filled with MDF is then mounted to the bearings, creating a weighted pendulum. The laser pointer is then attached to this with an adjustment screw for calibration.
Calibration is the tricky part. His new gimbal assembly is guaranteed to be perpendicular to gravity, but the laser pointer mount isn’t. Using a long tube filled with water he shone his laser pointer across his garden and adjusted it until it was parallel to his water-tube level. Clever!
We’ve actually seen a similar build a few years ago, with its own merits — though [Crispndry's] is a bit more refined.