Thanks for all the quick responses.
Some of the sources mentioned just didn't enter my befuddled brain, brilliant!
Sorry about the description I gave, not very descriptive from reading it again, so here goes:
Lengths no more than 250mm, any material except soft aluminum, so the walking sticks/tripods type ideal.
Tolerances are not critical, but should not be sloppy. It's not a precision instrument, just a work horse to carry in the car.
The inner and center tubes are locked together when extended, with a small three gear head* attached to the end of the inner tube, the complete assembly being turned by a folding handle at opposite end, with the loose outer tube providing hand support, with a moderate turning force only being needed.
*The three gears are arranged in a triangular form ala geared bending rolls, the main (upper) gear being driven via the center tube, the other two being supported by the end plates and free to rotate on axles, the whole assembly itself free to rotate about the main gear, for ease of positioning.
This is the best description I'm capable of right now.
Geoff – Coffee time.
Edited By OuBallie on 10/08/2013 09:28:58
Edited By OuBallie on 10/08/2013 09:56:41