Scratchy rotor valves

[meine]

Hello,

I have some rotor valves on one of my horn which scratch terrible during operating. Oiling them regulary and often doesn‘t improve it.

What can I do?

[Specialk3700]

Have you taken them apart and looked inside?

[meine]

Yes, they are clean.

[tbonesullivan]

Time for a tech to check them over. How old are they?

[MTbassbone]

I am not recommending this, but I have wondered why machining marks on the casing and router cannot be polished smooth. Maybe that would be nearly impossible to control. Is this what lapping is for?

[GabrielRice]

Take it to a good tech.

[boneagain]

I am not recommending this, but I have wondered why machining marks on the casing and router cannot be polished smooth. Maybe that would be nearly impossible to control. Is this what lapping is for?

In a properly set up rotor the core should not touch the outer shell.
The actual bearings are the shafts on the sides of the rotor.
Lapping does two things:
1) creates JUST enough clearance for the core to spin past the outer shell surface;
2) creates a surface that will not just shed the oil that goes on them.

Oil on the shafts reduces wear in the actual bearing.
Oil on the core impedes leakage between the intended air paths.

Leaving the oil out of the actual bearing results in faster bearing wear.
Worn shaft bearings can allow the core to rub against the outer shell.
No amount of oil will make a valve like that quiet. Or fast

A worn shaft is NOT the only reason for a scratchy valve.
The above is just an example (inspired by the "polishing" idea.)

Rotary valves are deceptively simple looking.

I second Gabe's suggestion of getting the scratchy valve to a good tech!

Ahhh.... wash the horn really well first, eh?
The tech will likely ALSO clean the tubes etc., but washing it first makes that less embarrassing for you and disgusting for the tech

[meine]

Today I cleaned the tubes and the valves and oiled them good. The scratching noise is much better after the first rehearsal, but not perfectly quiet

[boneagain]

Today I cleaned the tubes and the valves and oiled them good. The scratching noise is much better after the first rehearsal, but not perfectly quiet

Did you take the valves apart to clean them?

[meine]

yes

[boneagain]

yes

Good time for a tech, then. Inspecting will be easier with all the "surface schmutz" gone. Might be a simple as an aggressive tech cleaning or, as noted above, one or more of many other factors.
It should NOT be scratchy.
To me, scratchy means some kind of contact between the casing and the outer perimeter of the rotor itself. Those are NOT supposed to actually contact.
A tech can find the reason for contact and possibly fix it.

[timothy42b]

Just a thought.

You are assuming the noise comes from the valve. But the valve is operated by a multi-part linkage. (I don't know what model of horn or valve you have.) Mine has a trigger lever with a pivot axle and a spring, and a ball connection to the next link, which has a ball connection to the valve, which has both external and internal parts that turn.

Is there any chance the scratchiness comes from somewhere else on the linkage?

[davetrombizzle]

Today I cleaned the tubes and the valves and oiled them good. The scratching noise is much better after the first rehearsal, but not perfectly quiet

Did you take the valves apart to clean them?

Just being thorough with this line of thought. Did you actually disassemble the rotor and tap the core out? You may have something gritty in there that needs to be cleaned out.

[meine]

I don‘t think the scatchy thing is outside. I didn‘t clean the levers, but after disasembling the rotors (by tapping out the rotors), cleaning the tubes, the cases and the cores, oiling the cores and reasembling everything the noise get better. It didn‘t disapear, but it‘s better now.

Maybe I should disasemble everything again, clean it and reasemble everything with more care for clean surfaces.

[boneagain]

...
Maybe I should disasemble everything again, clean it and reasemble everything with more care for clean surfaces.

Did you find actual corrosion when you had it apart?

If you did not have green stuff, or black build-up on top of green stuff, things like case distortion and spindle bearing wear (from lack of oil by previous owner) bubble up the list of all the possibles. More cleaning won't do much for either of those.

A tech can do something about a loose spindle bearing.
If you wear down the outer circumference of the core before such a repair you could end up needing thicker rotor oil to avoid air leaks.

[meine]

No, there is no corrosion. I checked the spindles too, but I can‘t see any sign that these parts cause the noise. My guess is that the bearing plates I need to open to get the cores out could be not perfectly closed when reasembled. When I close them perfectl the rotors are stuck. When I let them a little bit open the rotors work.

[Burgerbob]

What are the valves?

[boneagain]

No, there is no corrosion. I checked the spindles too, but I can‘t see any sign that these parts cause the noise. My guess is that the bearing plates I need to open to get the cores out could be not perfectly closed when reasembled. When I close them perfectl the rotors are stuck. When I let them a little bit open the rotors work.

I would not expect corrosion on the spindles to cause noticeable noise. Let's say the spindle is about 6mm in diameter, with the rotor around 25mm. For a 90 degree turn of the rotor the spindle circumference will only rub against its bearing surface for under 5mm. For the same turn the rotor circumference could rub for nearly 20mm. If the spindle is worn off-center, the rotor circumference could rub for quite a bit of that 20mm.

Did you find and match up the "witness marks" between the rotor casing and the funky bearing plate?

If you did, and the rotor sticks when the plate is driven home, something is interfering with the side-to-side adjustment of the valve. It SHOULD have come from the factory quite free. Over time, side-to-side does tend to wear a bit looser. So sticking on an older valve is troublesome.

A tech can measure the diameter of the casing at different points, as well as assess the condition of the spindle bearings, as well as the side-to-side dimensions. A tech might not even need to measure. He or she will look at the pieces a little differently than most of us. Might be able to just look and say, "Well, THERE'S your problem."

You seem pretty interested in understanding what is going on. Some techs are open to walking you through what they look at. That kinda doubles the value you get for your money. Other techs charge more if you want to "help." They do that due to experience

Given your comment about the bearing plates (TWO removable plates?) I would recommend even more strongly to get to a tech. That's a bigger problem than the scratchiness. Could even be helping cause the scratchiness.

[brassmedic]

No, there is no corrosion. I checked the spindles too, but I can‘t see any sign that these parts cause the noise. My guess is that the bearing plates I need to open to get the cores out could be not perfectly closed when reasembled. When I close them perfectl the rotors are stuck. When I let them a little bit open the rotors work.

That's not really good. When you back off the bearing plate to get the rotor to work, is there then end-to-end play in the rotor? It's also possible the bearing isn't perfectly straight. Sometimes the valve jams when I tap the bearing plate all the way on, but if I tap on one side or the other of the bearing plate, I can get the valve to work. That indicates it wasn't too tight, but rather was not seated straight.

[meine]

That‘s what I meant Brad. I tap on the spindle where the linkage is and the valves begins to work. I can spin it completely around without problem, just the scratching ist there. Or was there. I gave now some bearing oil on the spindle where it goes out of the bearing plate and some valve oil in the valves. Now it works silent like it should. I‘ll take the horn to rehearsal next week, maybe the problem is solved.

[meine]

Given your comment about the bearing plates (TWO removable plates?) I would recommend even more strongly to get to a tech. That's a bigger problem than the scratchiness. Could even be helping cause the scratchiness.

Yes, it‘s a double valve bass trombone and it has 2 removable plates

[brassmedic]

That‘s what I meant Brad. I tap on the spindle where the linkage is and the valves begins to work. I can spin it completely around without problem, just the scratching ist there. Or was there. I gave now some bearing oil on the spindle where it goes out of the bearing plate and some valve oil in the valves. Now it works silent like it should. I‘ll take the horn to rehearsal next week, maybe the problem is solved.

I didn't say I tap on the spindle; I said I tap on the bearing plate, because sometimes one side of the bearing plate is higher than the other. Sure it will spin if you make the bearing really loose, but is it TOO loose? That can cause all kinds of problems.

[meine]

Ah ok, sorry, didn‘t get it right. No,it‘s fine, not too loose.

[LIBrassCo]

Dude is this the valves you just had made? Sometimes on brand new valves I end up having to polish the cores with 3000 grit wet sand to knock off a couple of highs. The clearance between the casing wall and the core can just be that close where taking off a miniscule about of material (something like .0001") combined with cleaning the hell out of it will fix the issue properly. Also, on Meinlschmidt and Caidex it's common to have to have to tap the spindle very little to give clearance for the valve to spin free. Nothing to worry about.

[meine]

Yes, but not the CAIDEX. These valves are just crazy great! Never had as good valves as these.
The problems I have are with the M&W. I just no tec here where to send them and I know to stay super careful with these valves.
Today the valves began to scratch again and I‘m sure it comes from the cores.

[hornbuilder]

Please, DO NOT start polishing the rotors with sandpaper!! That is indiscriminate and unnecessarily removing metal.

Obviously something got into the valves. What got in there? Who knows. But whatever it is has created a small burr somewhere which is creating the noise.

Is there any restriction in the movement of the valve? Or just noise?

If there is a restriction on the movement, the correct fix is to lap the rotor face, in situ, with a very fine lapping compound. If the issue is just noise, then keep the rotor very well oiled and play it. The thing causing the noise should flush out eventually.

[meine]

Hello Matt,

the action is perfect, the seal too. Just a noise. Can you give me a hand which lapping compound I could use? And of course, sandpaper will not even touch the valves

[hornbuilder]

Okay, so I expect that there is something in there between the rotor face and casing wall. Again, get oil down into the valve by dripping it down the handslide receiver with the valve depressed so the oil has a place to land. On the second dependent valve that can be a little more tricky. I suggest using what you feel is more oil than needed. It will get to where it needs to be.

If you're not experienced in lapping valves, this is not something to attempt.

And please, if in some rare instance where you do have any concern with anything related to M&W, please contact me directly, and I will guide you through the best options

[hornbuilder]

Question.
How are you seating the bearing plates? You're correct that if the bearing plates are not fully seated, the rotor can bind.

[LIBrassCo]

Please, DO NOT start polishing the rotors with sandpaper!! That is indiscriminate and unnecessarily removing metal.

A 3k wet sand takes off way less than the most commonly used laps. Would be the equivalent to a 2 micron lapping compound. Also I didn't tell him to do that, I'm saying what I do if there's a clearance issue.

[hornbuilder]

I know the clearance on my valves. I fit them myself. I do not use pre-fit valve assemblies. There are no clearance issues here. Sand paper and valve rotors do not mix!!

[meine]

Question.
How are you seating the bearing plates? You're correct that if the bearing plates are not fully seated, the rotor can bind.

I tap them back in till they are fully closed. Then the rotor is stuck. Tapping on the spindle reopens the bearing plate minimal and the rotors works again.

Question: could I use silver polish for the lapping? Just as an idea.

[hornbuilder]

No! Do not use silver polish!
"How" did you tap the bearing plates in? If the rotor is binding, the plate is not fully seated. I will make a video tomorrow to show how to properly seat a bearing plate.

[meine]

Ok, no silver polish, got it.

I tap it in with the plastic back of a screw driver. Sure not the best method…

[Wilco]

Gently set the bearing plate, a light push. Then screw the rotor cap on a bit thight. Get a piece of soft wood en gently tap with hammer. The cap will be loose, tighten again. Repeat until the cap doesnt come loose

[hornbuilder]

Gently set the bearing plate, a light push. Then screw the rotor cap on a bit thight. Get a piece of soft wood en gently tap with hammer. The cap will be loose, tighten again. Repeat until the cap doesnt come loose

Sort of..

He needs to know "where" to tap!!! It is possible to really screw the pooch big time if the cap is hit in the wrong place!!

I will make a video tomorrow showing him how to do it.

[BGuttman]

Gently set the bearing plate, a light push. Then screw the rotor cap on a bit thight. Get a piece of soft wood en gently tap with hammer. The cap will be loose, tighten again. Repeat until the cap doesnt come loose

The manual for my Mirafone tuba suggested this. Also, the maintenance kit included a wooden Crab Mallet. You would hit the cap right in the center so the force is distributed evenly.

[hornbuilder]

NO!!!!!!!

That is how you make a big mess!!!

PLEASE!!! I will make a video tomorrow!!

[meine]

Ok, I‘ll wait

[hornbuilder]

Please understand that I am the person that designed the valves in question, made and hand fit those valves, into this instrument. I have been a trained professional instrument repair technician for 25 years. I have been a trained professional instrument maker for 17 years. I have hand fit new/repaired many, many hundreds of rotor valves on trumpet, French horn and trombone.

If this were any other manufacturers instrument, I would not have said anything and let anyone with an opinion state that opinion. But because this involves something I personally made, I want to ensure that this scenario is taken care of properly. I understand people are trying to help, but please give me credit for having an understanding and expertise regarding my own instruments.

[tbonesullivan]

I've been playing trombones with valves for uh. 30 years now? I have never taken a rotary valve apart. Thayer valve? Sure but I've never removed the core from the backing plate. It's just not something I am comfortable with, as there are a lot of things that can be broken or messed up, and I don't want my "learning experience" to screw up one of my horns. I personally do not consider rotary valve disassembly to be part of "routine maintenance" that everyone should know how to do. And lapping a valve?? NOPE NOPE NOPE NOPE NOPE. I would also never give advice for anyone to try to lap their own valves unless they are a trained professional, and sometimes I feel that members of this forum are way too quick to suggest things like this.