(enlarged view)

After breaking one of the legs on my shop stool, I decided to build an adjustable version. I made the base from a pentagonal hardwood column, attached five hardwood legs with deep tenons, and then, for additional strength, routed slots in the column and legs for plywood brackets. After adding casters to the legs, I went on an unsuccessful search for a seat adjustment mechanism. Then the perfect solution came to me: the tail jaw of a 3/4-in. pipe clamp.

The bottom end of the pipe goes into a hole in the column, with the clamp jaw resting on top. At the top end, I threaded on a pipe flange for attaching a hardwood seat. To make the seat as strong as possible, I used the largest pipe flange I could find at the home center, which has a 4-1/2-in. overall diameter and fits onto 1-1/2-in. pipe. To make that work I screwed a pipe bushing onto the end of the 3/4-in. pipe to take it to 1-1/2 in. dia. Then I attached the flange and seat, and started using my new adjustable stool right away.