Saturn Water Keys

Discussion in 'The Rehearsal Room' started by Jack E, Aug 30, 2017.

  1. Jack E

    Jack E Well-Known Member

    I didn't want to hi-jack David Broad's thread about large-bore cornets, so I've opted to start a new thread.

    I followed the link in that thread to the website of Wedgwood Brass, and came across the following write-up on their Saturn Water Key. As well as being of great interest (says he of the permanently soggy right knee!:(), I found it hilarious, too! :D

    Wedgwood Brass - saturn

    You may find it worth a read, too,

  2. Tom-King

    Tom-King Well-Known Member

    Saturns work really well - nice simple design that just works incredibly well (if they weren't so damned huge that they'd hit each other, I'd have them on my sop right now).

    I'm not convinced that his dismissal of the Amado type is entirely fair - they do solve several problems that the traditional lever-type create and they're reliable (aslong as you feed them the occasional drop of oil) - but then if he didn't believe in his product I don't suppose they'd be made.

    I'll take Saturns or Amado's over levers any day of the week if I have a choice.
  3. BrianT

    BrianT Member

    Wedgewood say that using stainless steel in piston valves is A Very Bad Thing because stainless steel is not a conventional bearing material like bronze or monel.

    But they're more than happy to use a stainless steel ball bearing in the design of the Saturn water key.

    I don't understand why stainless is OK for one but not the other. I would have though that a hard stainless steel ball bearing in a brass seating would be more susceptible to wear due to the different properties of ball and seating materials.
  4. Jack E

    Jack E Well-Known Member

    In a piston valve, the valve slides up and down every time you use it - which is obviously a lot - and stainless steel is not very good at withstanding continual rubbing. I spent most of my working life as an engineering technician, in a variety of different fields, including working for two industrial instrument manufacturers who used a number of stainless steel components - but I cannot recall a single instance of stainless steel being used in a bearing application, either rotary or linear, where it would have to stand up to continual friction. That's why I was very surprised to learn that so many brass instruments use stainless steel for piston valves. Stainless comes in a huge variety of blends, with quite a variation in properties, with some grades having better surface hardness than others, but these piston valves are the only such application I've ever seen in which stainless steel is used.

    In contrast, the stainless steel ball in the Saturn Water Key has no sliding or rubbing motion at all; in use, it is lifted off its seat to allow the water to drain out, and is then pressed back onto its seat to seal. In this application, stainless steel is a good choice, as you can get it in a hard enough grade so that the ball will not deform (which would cause air leaks), and as long as it is exposed to atmospheric oxygen, it is highly resistant to corrosion.

    Monel metal is very good at withstanding both corrosion and friction - in fact, even better than stainless steel on corrosion - which makes it a damn good choice for piston valves, though it is far more expensive than stainless steel.

    HTH, and best regards,

  5. BrianT

    BrianT Member

    If as you say the ball is lifted out of its seating when you operate the surrounding ring then I can see there would be little wear. But I suspect that the spring presses the ball into its seating until a sideways force on the surrounding ring makes the ball ride up out of the seating. It'll either roll or slide - both movements will cause wear in the softer seating material. And then when you release the ring the ball will roll or slide back into place.
  6. Jack E

    Jack E Well-Known Member

    From looking at the design, Brian, the ball won't slide, so there won't be any wear caused by friction. It also appears that the rolling movement up the side of the seating will be maybe one sixteenth of an inch? And at a far lower speed than the movement of a valve over, say, three quarters of an inch, and with nowhere near the number of movements of a valve in a similar time of playing.

    Also, the pressure exerted by the spring is very light, indeed - so the pressure exerted by the ball on the seating as it rolls up will be minimal, and as the ring is unlikely always to be pressed at exactly the same angle, so the path taken by the ball up the angle of the seating will vary, spreading whatever wear ensues, rather than always being in one line. There's another point; even if the Saturn was to wear a groove in the seating, every time it returns to it's seat, it will put a tiny amount of pressure onto the line where the ball touches the seating - so it will be constantly moulding the seat to match itself.

    Re. the spring; the reason the spring can be that light is because - like poppet valves in car engines - when there is the maximum pressure inside the instrument, that air pressure adds to the spring pressure, helping the spring in keeping the ball pinned on its conical seat.

    With best regards,

  7. Fettler

    Fettler Member

    I suppose a waterway is also comparatively cheap and easy to replace. Worn valve casings from stainless steel valves probably mean it's new instrument time.
    Genius on the part of manufacturers really - an instrument that effectively eats itself and ensures steady repeat business.
    Last edited: Sep 5, 2017
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  8. Hsop

    Hsop Member

    Interesting about stainless steel valves. I have a B&H 921 cornet with stainless steel valves that was built circa 1977. The cornet has been used regularly and the valves are as good as any cornet available today. The different type of metal used on instruments is perhaps less of an issue when compared to the quality of the workmanship between different manufacturers.
    Tom-King likes this.
  9. Jack E

    Jack E Well-Known Member

    Hsop - I agree that quality of workmanship is a vital factor in producing an instrument which not only plays well but has a long working life, but the importance of choosing the right materials for each component cannot be underestimated.

    Basically, stainless steels are an alloy of iron and a minimum of 10.5% chromium - but I did a bit of reading up the different types of stainless steels - and there's a stack of them, with a very wide variety of metals and chemicals with which they can be alloyed (such as carbon, nickel, manganese, nitrogen, molybdenum, copper, niobium, titanium and aluminium), the proportions of which can also be varied significantly, in order to give the desired properties:

    Article: Stainless Steel Grades Datasheets

    My guess is that the type known as 'Precipitation Hardening' would be the best to withstand continuous friction, as well as being relatively easy to machine to intricate shapes. The advantage of these steels is that the hardening process used causes very little dimensional distortion, so you could be sure that the valves would neither leak nor bind. As the PH types use the more exotic ingredients, such as molybdenum, niobium and titanium, I'd expect them to be far more expensive than a bog-standard ferritic or martensitic stainless steel - but I'd also expect the PH types to have a far longer life.

    The other factor is, of course, what metal is used for plating the valve bore. Again, it's reasonable to assume that the better the metal is at withstanding the wear and tear, the more it will cost.

    As with most things, you get what you pay for.

    With best regards,

  10. Hsop

    Hsop Member

    Hi Jack

    Thanks for your post and article on stainless steel. I agree to a point that you get what you pay for but perhaps not in every case. One example I personally found out was when I had a Besson prestige cornet, regarded as one of the best (and most expensive !) cornets used in a brass band setting. For me this cornet did not offer what I was looking for in playing aspects so after about a year I sold it and purchased a sovereign 928 cornet which now provides me with the right instrument for my playing. The sovereign cornet was significantly cheaper to purchase than a prestige but still provides the same quality of workmanship and materials. It is a 2016 German made model that I own.

    As you mention there are so many grades and variances in metal quality, that for the customer, would prove very difficult in determining where the materials were sourced from. The right attention and care by the player can maintain the valves regardless of metals used in valve production, whether that be monel, stainless steel or nickel silver.

    The workmanship and time put into the design and engineering processes seem to definitely be the most important part of making a successful instrument. For example Eclipse, Taylor and Willson all use stainless steel valves and their workmanship that I have seen is superb. In comparison Besson and Yamaha both use monel valves with good results. You can find student marketed instruments sometimes fitted with stainless steel valves, sometimes with monel. There can often be issues with both types which highlights inadequate building processes and lack of skilled workmanship.

    In conclusion, different materials will have positives and negatives no matter which type of metal is used. Different manufacturers can have success with different materials but essentially the main cost of building a quality instrument originates from the design, research and the extensive labour time taken during manufacturing. Companies that produce instruments that have manufacturing issues will be built quickly to a specific price point, compromising the quality of labour. For example valves not properly lapped, slides either too tight or loose, soldering completed poorly.

    Kind regards
    Jack E likes this.
  11. Jack E

    Jack E Well-Known Member

    Yes, indeed - even the finest design can be let down by poor (or non-existent) quality control, as I've heard happened with Boosey & Hawkes / Bessons when a government initiative to get more youngsters playing resulted in them being swamped with orders. From different posts I've read on here and elsewhere - including tales of woe from people who worked there - quality control went out the window in favour of "Get 'em out by Friday!"

    There are some interesting posts on the subject of that company in particular, and about stainless steel vs. Monel metal valves, on this page of the TubeNet forum:

    TubeNet • View topic - Is Besson History?

    In the post by Donn (Feb. 22, 2006), he says:
    "Curious about 'stainless steel is not a bearing material' -- what does that mean? Web search comes up with many, many references for stainless steel bearings. Maybe I misunderstand."

    He's correct in that, but the bearings he refers to are roller bearings, not the type where one metal component slides over the surface of another - so the stainless steel surfaces only have to withstand spot pressure, rather than friction.

    The same problems caused directly by poor workmanship and non-existent quality control occurred with the early Range Rovers, whose bodies had no rust protection whatsoever underneath, apart from a coat of paint - which is why they are common donors of turbo-charged diesel engines to be fitted into older Land Rovers, as the engines and gearboxes are still going strong when the bodies have rusted beyond repair.

    Soon after the Evoque was launched, one of LR's employees claimed there was an area of ground three times the size of a football pitch near the factory, with Evoques packed into it like sardines - and all of them having been returned under warranty!

    When it comes to to standards of workmanship and quality control, the old warning in the Bible holds good:
    "Be sure your sin will find you out."

    With best regards,

    Hsop likes this.

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