Unique system on old buescher

[Elow]

I guess this is to help get that perfect 90 degree angle. Personally i probably would have problems because i play at kind of an angle, but it’s interesting because i have a buescher and it doesn’t have that. https://www.ebay.com/itm/114548962161

[shider]

If the opposite side has the same teeth this is not limited to 90 degrees.
You can lock your slide and bell section in small angular increments and the teeth secure the angle even if the friction fit is not that tight.
I can see the appeal to that, my bell section (on my bass trombone) sometimes starts to creep out of position if i don't check if the nut is tight every now and then while playing.
But it also brings problems: this is an overdefined system. If the conical interfaces are not manufactured (or were damaged) to result in the exact same longitudal position as the teeth, then there is either a gap between the rows of theeth when the conical interface is properly tightened, or the teeth are pressed against each other and the conical interface has not even made contact yet. This could in both cases result in rattling of the contact points and would be very hard to overcome in manufacturing.

[Basbasun]

I used to have a Bucher like that many years ago, you can have any angle, It did work very good. A perfect system.

[harrisonreed]

How long is that tenon?!?