4th valve slide moves out on its own !

[helle]

Hello all,

I got a Besson 967S which I had just 100% overhauled by a master instrument builder.
All slides feel snug and it takes some effort ( a few pounds of force) to get them moving, just as they should


Here is the thing though: When I play a single song the slide of the 4th valve moves out by around 2 inches. Yes two inches. On its own. During 4 minutes of playing.
Again, the slide feels very snug.
All 4 valves seem in the correct position.
The instrument plays fine.
This happens regardless if you use the 4th valve or not.

Has anyone ever seen something like that?

Thanks
Helle

[daruby]

What lubricating grease are you using. I would suggest Hetman #7 slide gel.

[ghmerrill]

Did the master instrument builder build in the self-tuning system? Maybe you're constantly playing a bit sharp on 4th valve notes and the instrument is attempting to compensate?

What does the master instrument builder say about this phenomenon?

[carbogast]

Maybe it is caused by air pressure developing when you are playing.

Not sure what kind of flaw would cause this, but you can test it.

Sometimes the 2nd valve can pop out; using a heavier grease often corrects it. That's what Doug was getting at. Make sure this isn't the case.

Then, pull the slide, place your finger over one opening, then play through all of the valve combinations (including all up). You shouldn't feel any pressure on your finger.

Then do the same thing for the other open tube.

-Carroll

[enhite]

I think that daruby is on the right track. Hetman makes a full range of tuning slide lubes, so switching to a "heavier" lube such as a Hetman 7, 7.5 or 8 might be a cheap, quick fix.

[ghmerrill]

I don't get the conjunction of

(a) All slides feel snug and it takes some effort ( a few pounds of force) to get them moving, just as they should. ... Again, the slide feels very snug.

and

(b) When I play a single song the slide of the 4th valve moves out by around 2 inches.

This suggests that there must be some significant force being applied in order for (b) to occur, and that the slide isn't simply "falling" out because the lubricating medium is too thin. 2 inches is a LOT to move if a slide is "snug". And where would any pressure come from? The air going into the instrument simply goes through it and a standing wave is set up by the lip buzz. So I wouldn't expect there to be any pressure measurable except perhaps by some very sensitive equipment -- and certainly not enough to be "forcing" a "snug" slide to move.

Maybe "snug" doesn't really mean snug, but more like "not falling out all by itself if the instrument is held without any motion or playing"? In that case, Doug's suggestion seems entirely appropriate.

?????

[helle]

daruby wrote:
<"What lubricating grease are you using. I would suggest Hetman #7 slide gel. ">


That is exactly what is being used ! (....while the problem is happening)

[helle]

Maybe it is caused by air pressure developing when you are playing.

Not sure what kind of flaw would cause this, but you can test it.

Sometimes the 2nd valve can pop out; using a heavier grease often corrects it. That's what Doug was getting at. Make sure this isn't the case.

Then, pull the slide, place your finger over one opening, then play through all of the valve combinations (including all up). You shouldn't feel any pressure on your finger.

Then do the same thing for the other open tube.

-Carroll

Great suggestion !
I tried it and ... No air is moving/leaking from other valves into the 4.th valve

[helle]

I don't get the conjunction of

(a) All slides feel snug and it takes some effort ( a few pounds of force) to get them moving, just as they should. ... Again, the slide feels very snug.

and

(b) When I play a single song the slide of the 4th valve moves out by around 2 inches.

This suggests that there must be some significant force being applied in order for (b) to occur, and that the slide isn't simply "falling" out because the lubricating medium is too thin. 2 inches is a LOT to move if a slide is "snug". And where would any pressure come from? The air going into the instrument simply goes through it and a standing wave is set up by the lip buzz. So I wouldn't expect there to be any pressure measurable except perhaps by some very sensitive equipment -- and certainly not enough to be "forcing" a "snug" slide to move.

Maybe "snug" doesn't really mean snug, but more like "not falling out all by itself if the instrument is held without any motion or playing"? In that case, Doug's suggestion seems entirely appropriate.

?????

Well, it takes some effort to get the offending 4th valve slide removed (Hetmann#7 grease, sticky stuff, you need to use some muscle)
And when I play a single song the slide of the 4th valve moves out by around 2 inches.


When I play, I can feel vibrations on the 4th valve slide. I'm now suspecting that the vibrations are "walking" out the slide.
Kind of like a piezo motor

So I checked if any soldering is loose on that slide, but it's fine. The amount of vibrations I can feel on the 4th slide also does not seem to be excessive, just normal for a played horn, I guess?
I'm baffled.

The guy who overhauled the instrument has not seen it yet, and he has a hard time believing it. It's a little haul to get to his place which is why I haven't showed him yet.

I will try to make a video .....

[davewerden]

I hate to ask a silly question, but have you ruled out pressure from your left forearm pushing on it? Otherwise, it is a great mystery! A video might be helpful.

[ghmerrill]

One speculation that seems consistent with your description ...

Suppose the overhaul tech polished the slide legs to make it easier to adjust. Suppose that he did this (it's actually easy to do this) in such a way that it was polished just a little too much along most of its length, but not near the tips of the tubes (like a trombone hand slide with the "stocking" that actually provides the seal while the rest of the inner slide leg isn't/shouldn't be in friction with the outer slide).

Then suppose that as part of the lapping, the final step was to lap it in by running it up and down with some lapping compound on it until it was nicely smooth. Again, this would end up lapping the tighter fitting ends of the slide ("stockings" now), and the insides of the outer slides, but only up to some small distance from the end. (Essentially the polishing and lapping has resulted in very slightly "belled out" inner slide ends, and relatively constricted outer slide ends.) So when you pull it out, it would go quite smoothly but get tighter near the end until it's pulled fully out. Also, the only think holding it in, once you've got it seated, would be just the "thicker" ends of the inner slide.

So you start to play it, vibration causes the inner tubes to work their way down toward the ends of the outer tubes, at which point things get tighter and require some additional effort to pull it free.

A fanciful story? Maybe. But there's a way to test it. Got a digital caliper? Take measurements of the inner tubes both at their tips and then at several places down toward the crook. If you get differences in the area of hundredths of an inch instead of thousandths of an inch, that could be a problem.

Or it could be that he just polished/lapped it, then expanded the tips, but didn't expand them enough or to a great enough length to be held in the outer tubes in the presence of the vibration.

All this is just a guess, but I've seen something like it happen. Sometimes, people get a little aggressive in trying to make things smooth and easy. I'd be surprised if your tech hasn't seen something like it as well.

Another possibility is that the slide legs (outer, inner, or both) weren't quite parallel (happens a surprising amount of the time), and he attempted to make it smoother by the lapping/polishing rather than realigning the legs (which is much more effort and trickier).

In any event, since this is a tuning slide and you don't need to adjust it as you play, it can almost certainly be fixed by just running an expander ball down each of those inner tubes for a certain distance so they'll provide more "grip" and not get jiggled out.

[booboo]

I hate to ask a silly question, but have you ruled out pressure from your left forearm pushing on it? Otherwise, it is a great mystery! A video might be helpful.

That would be my guess too. I've solved this on a couple of my instruments over the years by taking the slide out and very gently using the strength of one hand to push the slide legs (very) slightly towards each other. This essentially throws the legs slightly off parallel. When I say slightly, I mean slightly - less than you can see with the naked eye. The slide is then a little awkward to reinsert and stiffer to move, but stays put while playing. It's the sort of thing a decent tech would do in a minute - probably for free if you are a regular customer. I suspect that a tech may have a 'proper' or more elegant way of doing it also.

[ghmerrill]

It's the sort of thing a decent tech would do in a minute - probably for free if you are a regular customer. I suspect that a tech may have a 'proper' or more elegant way of doing it also.

A decent tech would use expander balls on the inner slide tubes rather than misaligning them by forcing them out of parallel. There's a way to kind of DIY that yourself, but I don't tell people who don't already know how to do it since it risks really screwing up the ends of your inner slide tubes. It's the sort of thing I've done on a couple of instruments, but on an instrument I valued for the long term and that was of a certain quality, I'd take it to the tech (who has approximately 8 million expander balls in order to do it right).

[booboo]

A decent tech would use expander balls on the inner slide tubes rather than misaligning them by forcing them out of parallel. There's a way to kind of DIY that yourself, but I don't tell people who don't already know how to do it since it risks really screwing up the ends of your inner slide tubes. It's the sort of thing I've done on a couple of instruments, but on an instrument I valued for the long term and that was of a certain quality, I'd take it to the tech (who has approximately 8 million expander balls in order to do it right).

Like I said, a tech would have another way!

[helle]

I hate to ask a silly question, but have you ruled out pressure from your left forearm pushing on it? Otherwise, it is a great mystery! A video might be helpful.

Well , to make a long story short ..... you hit the nail on the head.
My bare skinned left forearm was pulling the slide very slowly out.


I feel like ......