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French horn rotary valves have marks on the top, as seen below. These marks are put there by the valve maker when making the valve, and should be correct for optimal rotation.**
Check the outer mark first
There is a mark on the outside, at the joint between the valve casing and the inner bearing cap (out at the threads of the valve cap). That mark has to be lined up first, as it is key to the other marks being in the correct place. If it is not, you need to pop the top bearing off and reseat it correctly. If this is beyond your skills, you may want to refer the horn to a brass tech, but read on.
The marks on the bearing relate to the correct rotation of your valve
If these marks are off, you need to either trim the bumpers with a sharp X-Acto knife or put on a new bumper and trim it to size. Which also may feel beyond your skill level. But it is not that difficult to do any of these processes if you are moderately mechanical. I had figured out how to disassemble a valve and replace bumpers with no instruction whatsoever how to do it by the middle of high school.
Which brings me to two stories which may be of interest to readers.
Recent story #1: Valves in the wrong casings
A couple years ago I took my Patterson Geyer in to a local shop for an ultrasonic cleaning. I’m sure he has an assistant do most of this work, and the horn worked fine when I got it back.
Fast forward to last week. I have a scope that can be used to align valves, and I decided to check several horns. With the Patterson, some of rotation marks were slightly off when I looked down in the valves. I then started taking things apart and finally figured out that it was assembled incorrectly!
The parts are numbered on the valves, and you would guess that all the “1” parts would be in the first valve, etc. But the valve maker used by Patterson switched that up, the fourth valve is “1” and the first valve is “4.” The person at the shop had the second valve (marked “3”) correct, but all the loose parts of the actual first and third valve were reversed!
(Although, again, I can understand the confusion — the parts would set up the valve parts looking down the valve section as 4-3-2-1, but the shop guessed it was 2-3-4-1, and the stamped numbers on the outside of the casing are obscure).
When I got the parts all in the correct places the alignment marks were now correct! I just needed to replace about half of the bumpers to bring it all up to specs.
Aside: Bumper material
For the recent work I used some great material that was old round gasket material from our pool filter. It looks like a giant “O” ring, and I cut off what I needed. Very happy with it, have a supply to last me for years probably.
Recent story #2: Really difficult bumpers
The other horn that had some significant alignment issues was my Paxman triple. I could see a number of small issues and, with it being a compensating triple, I really wanted everything to be very correct, as on the F side the air goes through the valve section twice. And the horn was feeling super stuffy to me.
Again, that same local shop had cleaned the horn (I recall it really needed it!). Unfortunately, the bumper material they had used was mostly slightly small, things were over-rotating slightly.
I could on the other hand see why they used this material, as oh my these bumpers are so hard to put on. The area is so cramped, with too much tubing around the valve area. The Geyer style horn mentioned above, it is all so open and easy to work on. The triple, on the other hand, it really was a challenge, and I’m sure the shop must have struggled mightily with it.
Some of the shop bumpers I had already replaced in some prior work, using a couple different kinds of bumper material. Some I had done in natural cork and those all had to go, it was not holding up. Others were still holding up. In any case, I had to replace about half of the bumpers. Only 3 of the shop bumpers are still on the horn.
Again, as I worked over the bumpers I used the scope to double check the marks, which all were all essentially right on.
(I would add, yet another horn they cleaned at the same time, it still has all their bumpers on it and the alignment of everything is essentially perfect. I think the triple was just a challenge for them).
The results
Between these two horns, this was hours of work but with worthwhile results.
Both horns feel significantly better! As they should, as the valves really do need to line up correctly with the casings at each end of their rotation. The Paxman still feels stuffy but less so, and I think I can find a better mouthpiece for it when I get back in the office this week.
Overall, working on your valve rotation is totally work worth doing. Things need to be up to spec! If it is beyond your skills, it is still really worth taking a look and getting the horn to someone who can help you out.
**Sometimes, unfortunately, the marks are not actually correct. This is another reason for the brass technician to double check the marks using a scope. You can also get a good impression of the alignment without a scope with a strong light and looking down the valve tubes. It helps if the horn is screw bell to get your eye in the right place to look down the tubes.
