TromboneChat

Hi Everyone,
I have a Bach 42 and a 42 slide. The "nut" that holds the slide to the bell section keeps coming loose.
I have cleaned the threads and tighten it quite firmly , but after playing awhile it comes loose again.
Is there an easy fix? I don't want to use plumbers tape every time I put my horn together.

Thanks for any comments.

Randy

If the slide and bell section stay together and don't flop, I wouldn't worry about it. I think most of my horns do this to some degree.

i think the problem comes with people REALLY cranking down the nuts and it slowly loosens the threads over time and they wont stay fully tightened because of it. not stripped threads per se but stretched a bit. I usually dont crank my down. i twist till hand tight and then just slightly a bit more and check if the bell will wobble. if it doesnt, then it's secure.

You might take some extra care in cleaning any oil off it (both inner and outer threads) every time you take it out or put it in the case. This is really pretty much a matter of friction, and any oil (or slide lube?) on it will reduce friction. Also, wipe any oil/lub off the slide tenon and the inside of the tube it fits in. Any additional friction you can enhance there will be your friend.

On a tenor, that might be all you need to do the trick. On a bass it can be trickier just because of all the extra weight of the valve sections wanting to torque it away from you. I have no problem with my little Olds Standard, but on the bass I tighten that nut down and then tighten it some more, else I'll suffer from floppy bell syndrome pretty quickly.

Another note on oil on threads… probably doesn’t work quite like you think…. If there is oil under the head of the nut or on the threads, it will reduce friction. The important note here is that when you tighten a nut, ~50%of the torque should go under the head to friction, another 25% to friction on the threads. The balance is what holds things together (clamp load). If you reduce that friction, you will be over tightening the joint and probably stretching things out that shouldn’t be stretched out.

Cheers,
Andy