Fix for Slipping Bell/Slide Connection?

[bobroden]

I recently inherited a 1930s Conn 44H Vocabell trombone from a close friend. The horn has a great sound and a decent slide, but the connection between the bell and the slide is not tight enough: if you hold the slide, the bell section droops down, so that instead of sitting at 90 degrees to the slide, it sits at 180 degrees and points to the floor.

The usual cure for a drooping bell section -- which I use successfully on other horns -- is to push the two sections together as you bring the slide to vertical (i.e., 90 degrees to the bell section). But that's useless here, makes no difference at all.

I tried wrapping the shank of the slide with plumbers tape, but it didn't help.

I would like to fix this and extend the horn's useful life. Any ideas or suggestions? Or any recommendations for someone who could fix it?

[DougHulme]

I have variously found the following to help at different times with different horns.
1) use paper not plumbers tape. Needs doing every time but helps with the friction, Plumbers tape is too slippery.
2) degrease both inner and outer surfaces with a degreasant like alchol.
3) electroplate a small coating of metal. can be done at home with a bit of DIY skill.

The last one can be done quite thickly if you take it to a professional metal plater. The real answer though is consult a decent technician who has no doubt been presented with the same problem many times.

Doug

[Doug Elliott]

Most platers are not able to do brush plating that is required for that application. I hope I can try my setup sometime.
Try my fix of using a Sharpie to put ink on it... worked for me, even long term. I did that months ago and it still doesn't slip.

[BGuttman]

One thing that you must do: make sure to degrease both the tenon and socket completely. Any oil on either will cause the problem you describe.

Does the tenon "bottom out" in the receiver; i.e. seems to go to a stop before there is contact with the end of the socket before you get friction between tenon and socket? If so, even Doug's Sharpie solution may not work; although the paper trick probably will.

Sometimes a tech can sand a little off the end of the tenon to make it fit further into the socket, but that only works sometimes. If the socket is worn filing the end of the tenon will probably not help.

Brush plating is a pretty simple process. You can buy do-it-yourself kits on things like Ebay. You use the setup to "paint" metal on the tenon. If you paint too much on you can always sand it back off (carefully!).

[bobroden]

Hi Guys --

Thank you for the excellent insights and suggestions, much appreciated.

Quick update: I tried the alcohol cleaning and tried the Sharpie, to no avail. But the paper trick (a strip cut from a sheet of printer paper) does work, so at least I have a way to play the horn now.

Bruce, I suspect you're right about the tenon bottoming out, and your prediction about the paper trick was spot on.

Next time I have good tech person (my local guy is not one) I'll see if a more elegant fix is possible, but in the meantime this will be a big help.

Thanks again guys!

Bob

[bigbandbone]

I have variously found the following to help at different times with different horns.
1) use paper not plumbers tape. Needs doing every time but helps with the friction, Plumbers tape is too slippery.
2) degrease both inner and outer surfaces with a degreasant like alchol.
3) electroplate a small coating of metal. can be done at home with a bit of DIY skill.

The last one can be done quite thickly if you take it to a professional metal plater. The real answer though is consult a decent technician who has no doubt been presented with the same problem many times.

Doug

I’ve electro-plated at least a dozen slide tenons over my 44 year career. I did immersion plating in-house. I built up thickness with copper and finished with hard nickel.

[DougHulme]

Yep, thats exactly what I did... Doug

[mikerspencer]

I've an 88h and have had the same problem. I think the join was made from cheese and stretches/compresses over time. Eventually the bell section rests on the threads of the slide section and there's not enough contact to create friction.

I've had it fixed twice (in 25 yrs). I think the first time the tech managed to machine a little thread of the slide. The second time I think the tech expanded the slide above the threads to provide a greater contact area.

[ghmerrill]

I have finally resorted to using a fairly thin O-ring on my bass. It goes over the tenon and the nut tightens down on it. This requires a bit of effort, but when it's tightened down, the slide does NOT show any tendency to flop.

[BarryDaniels]

I had a brand new Yamaha 354 that had this issue caused by the tenon bottoming out. I just took a little off the end with a fine cut file. It only took 3 or 4 file strokes to fix the problem.