TromboneChat

I know I've posted before about this, but if anyone has a working slide lock for a '60's vintage Conn 50H, I am still interested in purchasing.
Several repair guys here have already taken the time to try to source a new one, but they are no longer available.
So - hoping for one off a donor slide, or one sitting in a parts bin.
The problem with mine is the threads are stripped on the lock itself.

Can you measure the threads on the cork barrel? It seems unlikely that the part is unique to this model. If you can get something with the right threading, at worst you might need to resolder the lug.

88H and various others are 13/16-40.

I was thinking the same as ithinknot (is that a tongue twister?), but then I realized that the slide lock ring for the Conn 50H was in the student (Director) style. It has a very different look than the Artist models like the 78H and 79H which are the same .522 bore size. Thus, it could very well be that the 50H has a completely unique design and size.

My recommendation is machine a threaded ring to the exact size and attach a hook.

Thanks, Brian and ithinknot. I have tried a 78H and 79H lock (both are here in the house, although they are my hubby's) and a 14H Director lock, with no luck. I think the 50H really is unique. Even the shorter cork barrel on the upper tube is a bit weird.

The 74H has similar/same different length cork barrels and a 0.522in bore so might have a slide lock ring that will fit. There was also a 75H Bb/F version and the 76H Century model at the same time, 1977-1983. Good luck in your search.

Cheers

Stewbones43

Mamaposaune wrote: ↑Wed Dec 28, 2022 2:08 pm Thanks, Brian and ithinknot. I have tried a 78H and 79H lock (both are here in the house, although they are my hubby's) and a 14H Director lock, with no luck. I think the 50H really is unique. Even the shorter cork barrel on the upper tube is a bit weird.

Hey Mamaposaune,

It has been a little while since I have seen a Conn 50H come through the shop. I used to recommend them (as used instruments) to my middle-school aged students as a transition instrument to a large bore trombone. Now I recommend a couple of other brands/model for that transition. That is probably a big reason why I don't see them anymore.

The shorter upper cork barrel is definitely a unique feature that gives the horn a special look. If I remember correctly, the slide lock ring has the threading on the outside (just like some of the Director models) and the cork barrel threading is hidden on the inside. Am I recalling that correctly, or am I confusing that with another model?

Brian, I just saw your last comment.
The 50H has the threads on the inside of the lock, I attached a picture above. Hope I'm understanding you correctly.
It just seems to be unique to the 50H. (the 74H, also a .522, may be the same)

Mamaposaune wrote: ↑Fri Jan 13, 2023 3:41 pm Brian, I just saw your last comment.
The 50H has the threads on the inside of the lock, I attached a picture above. Hope I'm understanding you correctly.
It just seems to be unique to the 50H. (the 74H, also a .522, may be the same)

I thought so. I have it notated in my Allied catalog that the Conn 50H lock ring with hook is no longer available. I'm sure there are a few of them sitting around in people's "spare parts" bins, but I imagine that most folks who have them have no idea what model trombone the part is for!

I still recommend that you have a part machined to match the internal threading on the cork barrel. Of course this presents a whole new problem. I am predicting that it would be rather tricky to get thread gauge tools in the cork barrel to get an accurate reading on those threads. In other words, the top half of the inner slide might need to be disassembled in order to get a thread reading. Once the threads are measured, the part should not be too difficult to produce. The ring is a simple column with part of it cut away slightly and then the external threads are turned. The lock hook could be made of rectangular rod that is bent at a 90 degree angle, cut to size and then soldered or brazed on the lock ring.

Another way around it is to assume that Conn used the same threading on their .500 bore Director horns for that style of a slide lock ring. Measure the threading on a .500 Director slide lock ring, machine the ring and hope for the best!

It might be easier to replace the cork barrel, no? There must be a gazillion .500 bore cork barrels with working slide lock ring hanging around

Matt,

I was thinking the same….just machine out the center and increase the diameter to handle the larger inner slide.

But….then I remembered that the entire inside might need to be machined out in order to have clearance for the outer slide. By the time you get the proper clearance, there might not be enough metal there to keep the threading for the lock ring to work.

Oh sorry I thought it was a .500 bore I misread that. I take it a 508 or 525 cork barrel would likewise not work?

A cork barrel designed for a .525 should work. The .003 inch can be accommodated for with solder. However, I don't believe such a cork barrel exists in the Conn "Director" style.

Crazy4Tbone86 wrote: ↑Sat Jan 14, 2023 12:42 pm I still recommend that you have a part machined to match the internal threading on the cork barrel. Of course this presents a whole new problem. I am predicting that it would be rather tricky to get thread gauge tools in the cork barrel to get an accurate reading on those threads. In other words, the top half of the inner slide might need to be disassembled in order to get a thread reading. Once the threads are measured, the part should not be too difficult to produce. The ring is a simple column with part of it cut away slightly and then the external threads are turned. The lock hook could be made of rectangular rod that is bent at a 90 degree angle, cut to size and then soldered or brazed on the lock ring.

Another way around it is to assume that Conn used the same threading on their .500 bore Director horns for that style of a slide lock ring. Measure the threading on a .500 Director slide lock ring, machine the ring and hope for the best!

Would it be crazy to create a cast of those threads, remove the cast, and measure the threads from the cast? Perhaps with wax or some low temperature moldable plastic?

Although, that might make a mess that would gum up the slide...

--Andy in OKC

Some creative ideas here, but definitely above my skill level. And although my hubby works part-time for a custom machine builder, it's not something they have the time or interest in tackling.
Really all I want to do is offer this 50H for sale, it's otherwise in great shape but (as anyone who has been around young trombonists knows) in the hands of a kid it's only a matter of time....

A reasonably competent machine shop (or repair tech skilled with machine tools) could measure the thread pitch and machine the part and braze on the locking mechanism as well.