Lost a locking ring? nut? on an old Bach 42B

[timothy42b]

Tonight I took the 42B out of the case and noticed shiny threads on the screw that adjusts tightness on the ball connection to the valve spindle (not the one on the thumb lever). I haven't seen those threads in a while because there was something covering them that is gone.

I haven't adjusted that in a long time but my memory says that there was a little knurled locking ring on it, and when you got the screw the right tightness then you tightened the ring to hold it there.

Is there a name or part number for that piece? Or a diameter and thread pitch for a replacement? It's a 1971 horn if that makes a difference.

Oh, the buzz on high A is gone, could be coincidence though.

[elmsandr]

This one?

8FA345EF-D498-444F-8FD2-6B6BA1564D87.jpeg

I couldn’t find a part number, I think they are trying to get everybody that needs one to change to the new miniball linkage and stop arm. That will cost an arm and a leg, however.

Send me an email or a pm; when I get home after the weekend I’ll check my tool box and send you one. I have many linkages sitting in bags there, one of them has to have a lock ring.

Cheers,
Andy

[Burgerbob]

Hickey's has those parts.

[Crazy4Tbone86]

Those lock rings are readily available. They are known to break or crack, so most shops keep them in stock. Yes, there are websites that sell them and/or you should be able to get one installed by your local tech. My recommendation is to buy 2 or 3 of the locking rings so that you are equipped for the next time one breaks.

Even though the Minibal linkages have been used by Bach for years and many players have updated their linkages, there are still oodles of players that have the old-style mechanical linkages. For this reason, I always keep several of those lock rings in stock. I think I still replace 6 to 8 of those every year…..and my shop is very small.

The old mechanical linkages work very well if you adjust them so that the parts have no “play” and use a high-viscosity lubricant. Be careful……don’t use too much pressure to tighten the locking rings. The metal on those rings is rather thin.

[greenbean]

When properly set-up/lubed, this old-style linkage can be GREAT. I prefer it to the newer "mini-ball" linkage.

[timothy42b]

I see that Hickey's carries a Bach lockring #079239.
I'm going to call the local shop and see if they have one, it might be as simple as driving over. If not I'll check with one of you or call hickey's.

[Crazy4Tbone86]

It might be best to get a couple of the locking rings. You never know!

[timothy42b]

I bought two of the lock rings from Hickeys.
Neither fits.
They seem to be the right number, old style lock rings for an old style plug, but they won't screw on. I took the plug out and tried both ends, no luck. The local repair guy said he used to keep them on hand but hasn't used one in a long time and didn't have any left. I'll give him a call and see if he has an idea why they don't fit.

[Crazy4Tbone86]

Hmmm?!? That’s a problem that I have never faced before. At some point, they changed the “look” of the rings, but the replacements always fit. Can you post a photo of the new rings?

[elmsandr]

Just did a quick check on a handful of these lying around here from the 40's to the early 00's.... I think they are all the same. I didn't get out the thread gages, but just a quick vernier check. I will say that getting them on the ball lock screw is harder than the one on the lever joint. That interrupted thread for the screwdriver slot can be quite a pain to align. Sometimes I like to take that screw all the way out and start the lock ring from the side with the full thread, but that is quite annoying to re-set the position as well.

Cheers,
Andy

[timothy42b]

I got a quick email from Chuck saying they'd sold thousands and none have ever not fit. I emailed him photos, I'll try to attach.

Yeah, that screwdriver slot made it hard to start, so I took the plug out, confirmed that the plug screwed onto the linkage either way, and then tried both lock rings from the internal end. They both seem to start but bottom out after a slight turn.

However. Perhaps I was hasty in my efforts, sometimes a thread has to catch at just the right point. I'll give that another shot. Meanwhile here are photos.

[timothy42b]

I have some hopes this is operator error, and if I get them aligned perfectly they will start. Then I'll have to apologize to Chuck of course.

[timothy42b]

I have some hopes this is operator error, and if I get them aligned perfectly they will start. Then I'll have to apologize to Chuck of course.

While that's still possible, I'm not convinced. I started the lock ring from the inner end, and the screwdrive slot makes it easy to see how many turns. At 2 1/2 turns from initial engagement the lock ring stops screwing on. At that point it is flush with the end.

It is possible there is enough thread damage that doesn't show - it's a beat up old horn, and that the threads could be cleaned up. But I am very cautious about forcing anything.

(should have bought a new plug at the same time I guess)

[timothy42b]

Ace Hardware has a board with various size bolts and nuts so you can test what you have.

The plug fits in the 5/16 hole. But it will not thread into either 5/16 - 18 or 5/16 - 24. Or M8 1.0 or M8 1.5.
The lock rings similarly will not thread onto bolts of any of those 4 choices.

Nothing else is close.

[Crazy4Tbone86]

Try flip-flopping the rings. It looks like you only need 2 or 3 rotations on the other ring for it to be in place.

[Doug Elliott]

It doesn't take much difference to have threads not work.
I don't have a 42B but I have a 36B, I'll see if I can tell the thread size.

[Doug Elliott]

It appears to be 5/16 x 32 threads per inch, which actually is a standard "extra-fine" thread size.
My guess is there's a small burr at the start of the thread. If you have good magnification maybe you can see it.
You could use a 10-32 tap to scrape the threads just enough to remove the burr.
The 5/16-32 tap is available pretty cheap on Amazon if you really want to get it for just one use. 10-32 can be found anywhere.

[Mamaposaune]

I had this problem with a used 42B that I purchased, the locking nut only went in about 1/2 way. Turns out the inside threads were damaged -I was able to mix-and-match parts with another 42B and 36B that I owned, so I was certain that the problem was with the inner threads on just the one linkage. (I put up an ad here looking for a replacement linkage.
As luck would have it, Hubby (also a trombonist) works part-time for a custom machinery builder, Scott. He took the parts in to see if Scott, who has ALMOST every tap made, had the correct size. He didn't but was able to determine the correct size and ordered one. Hubby and Scott took care of it - bottom line, problem fixed. I still have the tap and could loan it out, but buying new ($16. I think) may be cheaper considering the current cost of shipping.

[timothy42b]

So in that case you confirmed that the inner threads were bad and could be cleaned up with the correct tap.

That matches my thinking and Doug's comment above. But that also means that I got two bad lock rings from Hickey's. A Q tip does catch on rough places.

There is a lock ring on the other end of that linkage. After this weekend's concert I'll test that one on the plug; not going to mess with a trigger that's working now and might not tomorrow.

[Mamaposaune]

After re-reading your original post, I realize that I misunderstood the part you were talking about. It's the locking ring! Duh. When I looked at your pictures, it looked as if the nut wasn't going all the way down snug against the ball, which is the problem I was having.
Moving on...

[timothy42b]

Diagnosis is complete.

I removed the lever end of the linkage. Neither new lockring would thread on.

I tried the lever end lockring on my plug. It spun on easily from both ends of the plug.

Conclusion: I bought two defective lockrings. I've emailed Hickey's, they are usually pretty responsive. Also a forum member is sending me a ring.

This is scary because: The lawn tractor I gave to my daughter won't start. She has a huge lawn getting quickly overgrown. I ordered a carburetor from Amazon as I can't get any local repair tech to look at it, hoping it will fit on a 2000 vintage Murray. (The last cheap Chinese carb I bought was an exact match for a Toro push mower and I got two more seasons before it threw a rod. Sometimes even OEM parts don't fit.)

[timothy42b]

Update: Andy sent me a lockring that fit perfectly, problem solved.

The two lockrings from Hickey's were defective. I'll send them another note, hopefully they don't have a batch of 1000 left.