Thank you so much, those shaft collars look to be a much better design than the thing I drew (not much of a surprise to be honest!), I can stack a series of these instead of looking for one big solid one.
I didn’t know that the cylinders were so dangerous 😬 I must have lucked out; I’ve had to use extreme brute-force methods to dislodge the old ones when it was time to replacement them, pointing the thing directly at my guts and face while I work it loose with a hammer and spanner. Sounds like I was unwittingly playing Russian roulette with my chair. The difficulty I have in pulling out the cylinder is why I wanna just go with a “static” setup, it’s way too much work and effort for something so simple. Now I can also add “don’t want my cheekbones to get lodged in the ceiling” to the list of reasons to go static.