I need to fabricate a heavy-duty leg for a workbench. It needs to be about 30" high, with adjustable height (that is, with something like a foot with a threaded stud that can be rotated to fine-tune its height). I haven't engineered this with any precision, but I'd say that it should be able to easily handle 100lbs of load.
It seems like galvanized pipe or black pipe would be a good choice - very strong and not terribly expensive - probably 3/4" or 1" trade size. The upper end will be attached to a piece of steel angle, probably with u-bolts. I can imagine several ways of making the bottom end adjustable (to fine-tune the overall height).
Use an end cap at the bottom, and drill and tap that for an off-the-shelf adjustable furniture foot. However, would the metal in galvanized or black pipe fittings be suitable for drilling and tapping ? Somehow I imagine it as being too hard and/or too brittle. OTOH, threads were cut onto ends of the pipe, and into other fittings such as the end caps, so maybe this is a stupid question - or maybe not, maybe special machining was used.
Use a threaded floor flange. But it will rest against a nice hardwood floor, so it'd need some padding of sorts to protect the floor, especially when it's rotating. And I'm not sure how much adjustability it would provide, that is, how long the threaded portion of a floor flange is.
Use some sort of conical piece of steel - definitely suitable for thread-cutting or already threaded - that could be pressed into the bottom end of the black pipe.
And finally: could PVC pipe be suitable ? I'm sure at a sufficient diameter, and possibly using Schedule 80, it would be strong enough. But would threads cut into PVC plastic be able to handle the sort of loads I require ?
Any suggestions or answers to be above are appreciated.