Miraphone 5050 (2nd valve issue) Possibly Valve guide

[tonewheeler]

I've owned my Miraphone 5050 for almost 18 mos and have been experiencing an intermittent "sticky" 2nd valve issue while I play. Other than that, the horn has performed great. None of the other valves have given me any problem. I practice and play with a group on a regular basis.

I disassembled and thoroughly cleaning the horn and valves, only to have the same 2nd valve issue again. I finally broke down and took it to my local brass instrument repair guy. After looking he thinks it may be a worn teflon valve guide. He thought it looked really worn down, but wasn't sure. All the other valve guides looked the same. The channel for the guide is unobstructed. I'm now possibly looking at ordering a new valve guide -or- lapping the valve itself.

I was wondering if anyone here had a similar issue with their teflon valve guides on their horn, specifically the Miraphone 5050? I've searched the threads here without any luck for an answer.

TIA,
Dan

[jsmn4vu]

Lapping involves removing metal, and should be considered a last resort. While usually effective, it can result in reduced compression.
In the case of a valve that had once worked O.K., I would never lap unless there was some physical damage (e.g., metal deformed from being bumped, etc.). Provided there was no physical damage, a really thorough cleaning and possibly a new valve spring should get you going.

[davewerden]

Hold off lapping the valves until you're tried every other possibility. Is the guide easily removed? If so, take it off and see if the valve works differently (obviously it won't blow very well this way!). But the only problem I am used to seeing from plastic guides is that they get "mushroomed" at the bottom from hitting the casing too many times while you are putting them in. I had to do an emergency fix once for Ann Balwin Hinote just before a recital; her Willson's guide on one valve had been deformed slightly on its bottom side, so I carefully trimmed it with my ever-present Swiss Army Knife. Look it over carefully for this type of damage.

Also, does the valve work for a few minutes after cleaning, or does it never work well? If the former, you may still have gunk getting to it from somewhere. One common problem is the bottom cap. Make sure that is clean, because junk accumulates there. This is particularly likely to get into the valve action if you rest the horn on its bell, when the valves would be upside down. Don't do that - ever! I got out of the habit years ago.

[RickF]

Hi Dan,

I'm not familiar with the guide design of the Miraphone 5050, but if it's similar to the nylon or plastic guides of Yamaha, sometimes the guide can develop a 'feathered edge' where it rides inside the cylinder's groove (but I think the brass tech would have noticed that). When I had this problem - and didn't have any spare guides, I removed the guide from under the valve stem and lightly filed off that feathered edge with a nail file.

Maybe you could swap the guides between the 2nd and 3rd valve to see if the 3rd valve starts to stick, or... is that not possible? Just a thought.

[tonewheeler]

Dave, et al,

Thanks for the great suggestions and clues to the problem.

I rarely (almost never) set the horn on its bell and use a stand. The horn worked well for about a day after cleaning it. I also had checked for obvious signs of gunk when I cleaned it and the spring seemed fine.

My repairman also had the same concerns about doing a lapping, so it would be a very last resort. I'll report back early next week with the results.

Thanks again!

[davewerden]

It is possible that the lapping compound used on the horn when it was made is "hiding" in some of the tight curves of the horn. Some of these compounds are oil based and can be very difficult to swab out (or even find!). After you clean the valves it might work fine until a minute amount works its way back to the valves.

You can test my theory for about a buck. Get a bar of Ivory soap (not the liquid, nothing fancy, just the white bar). When the valve sticks, take it out of the horn. Lather one hand under running water with the soap and rub the lather all over the piston. Put it back in and play (it lubricates pretty well until it washes out as you play). If the valve immediately works fine for you, then it probably is due to lapping compound or some other oily crud finding its way into the valve. If you have the repair guy give it a good flush/clean job the problem may go away.

Also, IF you are using synthetic oil, clean the valves again and try petroleum oil for a while. Synthetics don't work well for me when I'm playing on a cool horn - moisture condenses in the horn and the syn oil does NOT like it! It could be specific to one valve due to the way moisture collects in the horn.

[djwpe]

I have 2 5050's, and get occasional intermittent sticking on both. The cause is usually something stuck in one of the knuckles, like grit, or a cat hair.

On one occasion after verifying that the valve and casing was completely clean, I inspected the guide with a loupe and discovered that the bottom was mushroomed slightly, probably from inserting the valve with the guide not aligned with the slot, and letting the guide hit the casing.

i shaved the corners of the guide with a single edge razor blade, and combined with taking care not to let the guide hit the casing, the issue has not recurred.

[Snorlax]

I have some very light sticking on the FIRST valve. I don't have a loupe-de-loupe (what is that, BTW? Do only PEs have access to them?) to examine the guide in detail, but I am wondering if perhaps I picked up the horn by the first valve slide once or twice and made the casing out of round. The slide is braced, but who knows?

Also--I have an extra set of guides that I got from Hornguys. I have been a bit reticent to replace my existing guides--now two years old--because it doesn't seem easy to do.

Don or Dan: Have you replaced any guides? If so, how?

Jim

[djwpe]

Jim- I doubt you bent anything. This horn is built like a tank. The first valve sticks on both of mine, the new one more than the older one. I think it's mostly just the very tight tolerances of the valves, combined with dirt. The guides are easy to replace; unscrew the valve stem from the body, and worry the guide out of the body by moving it up and down. Press the new one in. Done.

The loupe is not an engineer's tool. It's left over from my late wife, the photographer.

[tonewheeler]

I'd like to be able to test your "soap" theory, but the horn's at the repairman for the rest of the weekend. I'm going to leave it up to him for now and see what he comes up with. I spoke with him over the phone this afternoon and mentioned my concern about lapping and ruining the compression on the horn. The repair tech has a great reputation.

Replacing the guides may be the way to go, but I'm just going to let my repair tech do his job.

I was wondering if Jim or djwpe might want to post a pic of one of the valves depicting the valve guide? I'd be interested in comparing to mine.

Either way a sticking valve, even an intermittent one, is unacceptable.

I'm wondering if this is an inherent flaw in the 5050....hmmm....