I am new to this sort of thing and so hoping that folks are still active on this forum.
I have a small mechanical conundrum to solve. I am trying to construct a linkage between a large ball socket and a 2 plane potentiometer cannibalised from a games console controller. The linkage needs to have ball joints at either end but because the two items being connected have different sized ranges of movement, I think I am going to need a telescopic section in between the ball joints.
Sorry if my explanation isn't very clear! I had thought about chopping up some bits of aerials and so forth as I have tried all the sources I can think of from RC helicopters to various other things to no avail!
The forum is a bit quiet of late, but the regulars still read new posts and will respond if they can help.
If you look at the prop shaft on a car you will see that there is a splined shaft at one end to allow for changes in the distance between the back axle and the gearbox due to suspension movement. You need a sliding spline connection by the sound of things. It would be very difficult to make one from scratch as you would probably need to broach the splines. The Carden shafts on Shay logging locomotives used a system of square shafts sliging inside square section tubes to allow for the drive to the articulated driving trucks. Maybe you could develop this idea.
K+S metals sell small brass tube (Look for their display rack in model shops) If you could find two square section brass tubes that slide inside one another I am sure you would have the makings of a telescopic joint capable of transmitting rotary motion as long as the torque was not too high.