TromboneChat

Sunday second song needed a horn intro, due to basically an acoustic set, plan was to pull out the French horn. Uh-oh, first valve very tight. Popped top cap off and oiled it. No change. Pulled tuning slide and dropped oil,into the valve, still no change. Since I’ve owned the horn, the bottom cap has not been off. Mechanical linkage valve, a retaining screw has been broken off blocking access. Knurled knob to remove the screw is broken, only the threaded portion remains. Million dollar question is, did the knob break off because the threads are frozen and got twisted off, or due to physical damage? Threads recessed, nothing to grab ahold of. I got lucky with a left twist drill bit getting a broken head bolt out of an engine once, guess I’ll give it a try on the horn. Hmmm, not sure if I’d be happy or sad to never play that horn again! Good news is, trombone covered the moving intro just fine with the acoustic guitar holding a chord. Funny, since the trumpet duet a couple weeks ago, leader wants more horn taking a lead and not just filling the sound out. Just won’t be a French horn for awhile, unless I can bum my daughter’s double horn…

I have one rotor that the interior threads on the spindle are messed up, so I can't put the screw in at all. When I need to take it apart, I use a drift punch (I took a grinder to a punch and shaped it to match the shape of the hole in the stop arm).

If that retaining screw’s been untouched since you got the horn, there’s a good chance corrosion locked the threads, the knob probably sheared off under stress. A left-hand drill bit might work, but if that fails, you might be looking at tapping it out or getting a tech involved. Sounds like your trombone already earned its keep as backup!

That’s my $15 high school auction French horn. Bought it when daughter was just starting out on French horn to help her along. Used it once in a community band, played some Christmas duets with my daughter, and basically resisted all thoughts of tossing it in the stream in front of our place. Still haven’t mastered lip trills. It’s paid its dues! Trombone gets used every week, horn maybe once every 6 to 8 weeks. If I had to keep just one horn, it would be my trombone. Or maybe my euph. Or maybe my trumpet. Tuba…no commitment to that horn that was gifted to me.

Inserting random but weirdly relevant Broadway tune:

Before I take to drilling, I may pull the old maintenance trick of using one of the best penetrating oils there is. ATF. I’ll pull the slide and flood both sides of the valve. Too much baggage last week, didn’t bring horn home to try anything.

Not quite following your description of the rotary valve. You mention pulling the top cap off and oiling…..that would be the bearing plate. Then you state that the bottom cap has never been off. There is no bottom cap on a standard rotary valve. Many horns have knurling at that spot but there is no removable cap. To remove the valve core, you will need to remove the stop arm and gently tap on the spindle with a rawhide or delrin mallet to work the bearing plate and valve core out.

The retaining screw that you speak of sounds like it is on the threaded rod that holds all three levers in place. Usually that rod moves freely and just slides in and out (thus, the need for the screw at both ends). You should be able to grab the end that is not broken off and work the rod out.

Rotary valves freeze up on people and most folks just add valve and think the problem is solved. If there is calcium and other mineral deposits in the valve, the problem could come back quickly. Best to get it to a technician for a chemical or ultrasonic cleaning.

Talking a really old Carl Fisher mechanical linkage French horn. Top cap removed does reveal the bearing, which easily lifted out. Gotta get bottom cap of to access other side of the valve. Brought the horn home today, will work on it in my spare time…probably sometime in January if I’m not inundated with snow. The threaded rod you mentioned is in good condition, much smaller diameter than what I’m looking at. Broken screw is in the quarter inch diameter range.

Just so we're all on the same page here...

The screw that is broken off is the spindle screw? Like the one the arrow is pointing to in this picture?
And it's broken off flush or below flush with the top of the spindle?

I still doubt there is a cap on the other side. Again, there could be knurling, but that does not mean that there is a removable valve cap or removable bearing.

Some of the modern trombone valve designs have caps/rings and bearing plates on both sides. Even with those, the valve can be removed by removing the cap and bearing plate on just one side.

Yes. Spindle screw. Other 2 valves have a knurled top to grip and remove threaded portion. Broken one is below flush. Was gonna send a pic, that one is close enough. What horn is that?

BrassSection wrote: Mon Jul 28, 2025 12:14 pm Yes. Spindle screw. Other 2 valves have a knurled top to grip and remove threaded portion. Broken one is below flush. Was gonna send a pic, that one is close enough. What horn is that?

Random Carl FIscher off of eBay.

Nicer than mine! Probably going for more than the 15 bucks I paid for mine…in the 80s.

Maybe I’ll play some heavy metal instead…haven’t had this horn out for a few years