old Conn valve stem breaks from piston ... how to fix?

[mwpfoot]

The first valve stem keeps breaking off from the piston in my old Eb Conn Helicon. Never at home in practice - only at the gig. Gah!

It seems like the stem is wedged in there and soldered. There are no threads on the piston end at least. It heats up and gives up. The fix mid-song is to take the valve apart, jam the stem back in, and reassemble. It holds together again until it doesn't. Um... drum solo!

This has been "repaired" once (I assume cleaned and re-soldered) but it has started failing again. So my enthusiasm to take it into the local guys for repair is tempered a bit by that.

What's the next step here? Is there enough material in the piston to safely put some threads in place of the failure-prone hole? Or?

I mostly play trombone.

Thanks,
Mark

[Dan Schultz]

There are several ways to fix this.

- If the threaded hole is just a little oversized... a little hard solder can be put in the hole and the threads retapped.
- If the threads are beyond repair.... the hole is drilled out oversize and a brass plus soldered in. Then, a hole is drilled in the plug and fresh threads cut.

I've been known to tap the existing holes oversize (1/4-28) an use King stems. Your fingerbuttons wouldn't work but King buttons are easy to adapt.

Just soldering the stem into the piston is a quick fix but not usually my choice.

[mwpfoot]

Hi Dan, I got this horn from you back in 2011. It's been great fun.

I think it will have to plugged and have new threads cut.

Would the piston top definitely have been threaded to the stem originally? If so, there's no clear evidence of it ... and I'm concerned that perhaps there's still some stem in there, which would complicate things for who ever does the threading.

How deep would the threads go? The way it's wedged in there now is maybe 1/8".

[Doug Elliott]

I have done that repair on a number of valves for a local repairman since I have the equipment to do it.
My preference, which usually works perfectly, is to bore a centered hole (the hole is always off-center after a repair like that) and install a HeliCoil to bring it back to the original thread size. It will never strip out again, and you can use a correct valve stem.

[Dan Schultz]

Hi Dan, I got this horn from you back in 2011. It's been great fun.

I think it will have to plugged and have new threads cut.

Would the piston top definitely have been threaded to the stem originally? If so, there's no clear evidence of it ... and I'm concerned that perhaps there's still some stem in there, which would complicate things for who ever does the threading.

How deep would the threads go? The way it's wedged in there now is maybe 1/8".

Interesting. The top of the piston would have been threaded from the factory. Although not the best way to fix stripped threads.... the stem was probably soldered in when I got the horn and was still that way when I sold you the horn. Send me the piston and I'll fix it. Measure your other stems and include the fingerbutton you are using.

[mwpfoot]

Here's a couple pics. I was wrong about the depth, more like 1/4".



Doug, thanks for the info. I think I get it now - as some point it was drilled smooth and plugged, but then the threaded plug broke free. The subsequent quickie solder job by the repair place that shall not be named (it was free, and I had no idea what I was asking for, but ...) seems to have melded the male threads on the stem to the plug and seriously confused me as to what I was looking at since they appear one piece to a n00b like me. (I'm still afraid to fiddle with the other ones to see how they attach.)

Dan, that's a very kind offer, thank you! I'm kinda done with the shop here so I'll send back to you so many years later for a reunion. It could easily have passed through your hands appearing secure, since it didn't budge until an hour into my New Orleans sets, at which point it failed every time. I had to pull pretty hard to detach it again for the pictures. Heat expansion is weird stuff.

[Dan Schultz]

Here's a couple pics. I was wrong about the depth, more like 1/4".....
Dan, that's a very kind offer, thank you! I'm kinda done with the shop here so I'll send back to you so many years later for a reunion. It could easily have passed through your hands appearing secure, since it didn't budge until an hour into my New Orleans sets, at which point it failed every time. I had to pull pretty hard to detach it again for the pictures. Heat expansion is weird stuff.

Just measure the other stems so I get the extension right and send along the fingerbutton. I'll turn it around the day I receive it. It the other stems/pistons are showing signs of distress... just send them along too an I'll fix 'em. .... gratis.

Dan Schultz
5211 Old SR 261
Newburgh, Indiana 47630

[mwpfoot]

It's in the mail; valve, stem and button should get there Monday.

There's a note in the box but the stems extend just under 1 3/8" above piston top by my measure: 1 11/32" if being precise. Or maybe you meant diameter.

Thanks, Dan!

[arpthark]

^ good customer service in action.

[Dan Schultz]

It's in the mail; valve, stem and button should get there Monday.

There's a note in the box but the stems extend just under 1 3/8" above piston top by my measure: 1 11/32" if being precise. Or maybe you meant diameter.

Thanks, Dan!

OK. I'll watch for it!

[roweenie]

^ good customer service in action.

Dan is awesome.

[mwpfoot]

Agreed!

[Dan Schultz]

It's in the mail; valve, stem and button should get there Monday.

There's a note in the box but the stems extend just under 1 3/8" above piston top by my measure: 1 11/32" if being precise. Or maybe you meant diameter.

Thanks, Dan!

I received your piston in the afternoon mail (Saturday). I'll fix it in the morning and have it headed back to your Sunday afternoon. My post office is four doors south and has one of those automatic mailing machines in the lobby.

I don't recall the exact particulars about that horn but it appears that it had a valve job. If the pistons go to Anderson with the stems assembled... EVERYTHING gets plated with nickel... including the stem. That stem was soldered in but wasn't causing problems so off it went with the valve section for refitting to the casings. The stem just waited until now to 'give up the ghost'.

I'll solder in a tapped plug and provide a new Conn stem that will match your other stems.

[Dan Schultz]

Sequel.... your piston/stem is heading back this morning. The original 'fix' WAS a threaded sleeve soldered into the piston. The solder on the sleeve came loose but it was also soldered to the threaded part of the stem. That's why the stem appeared to be smooth and without threads.

Anyway.... it's fixed now. With a new sleeve soldered into the piston and a new stem. All is well!

[mwpfoot]

Received, looks great, installed, played great, thanks Dan!

Very, very cool response to my rambling "I don't understand what I'm looking at here" post.

My next tuba gig will be the big test, that should be in a year or two.

I browse your list now and then for a budget BBb Conn sousa- or heli- or maybe recording, but it's just dreaming until I get off my butt and sell enough trombones to pay for one.

I get a lot of questions about the helicon everywhere it goes, which is fun, I'm happy you give these things new life - people really do enjoy them. Here it is included in the staging when we sold our previous house, it is the only thing we actually owned in this picture:



Cheers to Dan!

[Dan Schultz]

Glad you have the piston back and all is well.