Rudall & Rose Patent Head Maintenance



Rudall & Rose brought out their Patent Head in 1832, making it the subject of their first patent.  They seem to have made quite a few of them, and because of their unusual features they often show up requiring maintenance.  The purpose of this page is to provide a place where information, hints and tips on this topic can be assembled. 


If you are unfamiliar with the Patent Head, proceed with caution.  You cannot manually alter the setting of the tuning slide as you would with normal flutes - attempting to do so will damage the internal mechanism.  Attempting to turn the head relative to the barrel will snap off the guide key shown at top left in the image below. 

Only ever adjust the tuning slide position by rotating the end cap and proceed cautiously.  As will be seen below, the screw mechanism can be easily damaged by excessive force on the cap, and replacing the damaged items will involve a lot of painstaking work. 

Review the drawings and photographs on the pages linked above before proceeding.

Partial disassembly

As shown here, full disassembly is quite a business, but is fortunately not necessary for most maintenance tasks.

(Click here for an item-by-item explanation of the parts above)

For most routine maintenance, it is enough to separate the barrel and head sections.

To separate the barrel section and inner sleeve from the head section:

  • Gently unwind the end cap (turning counter-clockwise) until you reach the end of slide travel (the slide opening should be about 30mm, about 1.25"). 

  • Do not use force to go any further!  Indeed, turn the cap slightly inward to free the stopper from the end stop.

  • Use a suitably prepared rod inserted up the bore to engage the face of the stopper and rotate it counter clockwise until it can be heard or felt to "click" on the end of its thread.  (Suitable rod suggestions below.)

  • Undo the cap further until the head comes right off.

  • Use a thin rod (eg a standard metal flute cleaning rod or some stout wire) through the hole in the cap end of the inner tube to push the stopper out through the barrel socket.  Be careful not to damage the threaded hole in the centre of the stopper.  Indeed, it might be wise to drop in anything suitable that will fit through the embouchure slot on the liner (eg a small washer or coin) to spread the load of pushing out the stopper.

Suggestions for the rod above:

  • In principle, the rod:

    • should be of the largest diameter available that will freely pass up the bore.  In practical terms, that probably means 16mm (5/8") as material in these dimensions is readily available.  A thin rod should not be used, as it will apply its pressure to the unsupported middle of the stopper face

    • should be finished off squarely at the stopper end, and rounded comfortably at the handle end,

    • should stick out long enough to be able to put some rotational force on it, and

    • should have something of a high friction surface treatment at the stopper manipulating end.

  • I have used my usual stopper removal rod, a length of 16mm diameter delrin.  To improve the gripping ability, I dropped a rubber bung down the head bore first.  The bung should be a free fit and be inserted so that its wider end abuts the stopper face.

  • Jem Hammond reports success with a thick wooden dowel with a hollowed end

  • David Shorey reports success with a piece of closed cell foam punched out and glued to the end of a dowel.

Having subsequently tried David's suggestion, I'm going with that from now on!

At the rod's other end, it could usefully have grooves to mark:

  •  the stopper distance when the slide is fully extended, about 16mm

  • what we find our stopper distance to be at A440 (to be determined), and

  • the stopper distance when the slide is fully closed, about 21mm

Elsewhere on the rod, somewhere where they won't be confused with stopper marks,

  • two grooves showing where the rings are at the expected maximum opening distance of the slide (circa 30mm apart).

These would make it possible for the owner / repairer to check the operation of the mechanism easily. 

Further disassembly

For most routine maintenance purposes, further disassembly should not be needed, but these notes are included in case you need to go further.

To remove the two-speed shaft:

(Why would you want to do this?  I've found it useful to do when replacing the cork sheet around the stopper.  As we'll see below, the amount of friction is critical, and it's useful to be able to screw the stopper onto the end of the two-speed drive shaft to be able to offer it (facing the wrong way!) into the copper tube at the barrel end to test the fit.)

  • unscrew the two small screws to remove the end cap.  Immediately put the tiny screws into a ziplock bag or screw them back into the drive plate below the cap for safety!

  •  remove the pin that secures the plate by rotating the end of a flat screwdriver in the gap between the tip of the pin and the rim of the plate.  Pull the loosened pin with long-nose pliers.  Add these bits to the zip-lock bag!

  • remove the now-loose drive flange and push the exposed end of the two-speed drive shaft to eject it into the head.

Going further:

  • three tiny screws retain the shaft bearing in the end of the outer head.  These always seem to have the heads ground flat (whether by intent or wear is not clear at this time).  If they need to be removed:

    • new slots will have to be cut in them with a suitable shaft tool, or

    • the screws will need to be drilled for a screw remover, or

    • the screws will have to be drilled out and the head tapped for new screws.

    • conceivably, a soldering iron could be used to tin the end of the screws and then switched off and allowed to cool in contact.  If the joint holds, turning the soldering iron might unscrew the screw.

      (I have done the first of these, but not any of the others.)

The two-speed drive shaft

Interesting to note that the four-start thread of the drive shaft (labelled "a" in the drawing below) at least on the examples I have seen, is not so uniformly threaded that it will run freely in all four possible starts.  When reassembling, make sure to test all four options and pick the most free-running start!

The course thread fits a 13TPI thread gauge convincingly, but, given that there are 4 separate threads, this really implies a threading rate of 3.25 TPI.  It's outside diameter is 7.24mm, somewhere between 9/32" (7.14) and 5/16" (7.9mm). 

The finer single-start thread at the stopper end of the drive shaft has a diameter of 4.92mm, slightly larger than 3/16" (4.75").  The thread, which also takes the Acme form, is 20tpi, which makes it still coarse by normal standards.  The nearest equivalent screw in BSW, 3/16", has 24tpi.

The drawing in the patent document shows the stopper with a sturdy central boss to provide plenty of depth for the screw thread.  The example before me just has a 1.67mm (nominally 1/16"?) brass plate at that point.  At a thread pitch of 1/20", that only allows a thread depth of 1.25 turns!

Given the unusual nature of the threads, great care should be taken of the shaft and the stopper thread, as replacing them will require some pretty nifty thread cutting on the machine lathe.

The Stopper Face

It seems common that the stopper face on this head is missing, suggesting that it was inadequately held in place.  We understand it to be of sterling silver, approximately 0.4mm thick, and of diameter just able to move freely inside the bore.  The bore measures at about 18.67mm in diameter on the sample under examination.

It has been suggested that the stopper face is held on using soft solder, but this has not been confirmed.  The cylindrical part of the stopper is made from brass sheet soft-soldered along the seam, and the tapped plate inside is also soft soldered in place.  Given the very good likelihood of these other joints coming unstuck while reaffixing the face, it might be cheap insurance to glue the face on instead of soldering.  This might also save replacing the stopper cork if it is still serviceable.

Here's a solution that works.  Clean the inside of the deeper end of the stopper tube and score it to provide keying for the glue.  Score the back of the face plate similarly.  Coated the inside of the deep end with epoxy, being careful to avoid any getting near the central tapped hole.  Place the face plate with the scored side upwards on the desk, and position the stopper centrally on top of it.  The glue should run down inside and form a more-than-adequate bond.

A design weakness?

Something that has always puzzled me is what keeps the stopper from rotating?  If it rotates it will mess up the desired relationship between stopper distance and slide opening.  The only answer I can come up with is that it is the friction between stopper and the tube it runs in.  So we don't want that to be too little.  But, for free movement of the slide, we can't afford that friction to be too high.  I never like systems that depend on the Goldilocks perception of ideal friction - "just right"!

But thinking about it some more, there is a "sort of" anti-rotational force at work.  The silver end of the stopper runs through that section of the inner tube that has the long embouchure access slot in it.  So we can imagine that the cork facing "gets used to" having a bit more freedom in that sector, and will thus be loath to leave it.  Hmmmm......

Reinstalling the stopper

The need to get the stopper in the right part of its rotation means we can't just screw the stopper onto the end of the two-speed shaft and forget about it.  If we do it up too tight, then it will definitely rotate, and get us into all sorts of trouble!  If we don't put it on by enough turns, it will unscrew.  Unfortunately, it seems Rudall & Rose have left us no real guidance in terms of installing the stopper, so I guess we have to come up with our own.  Here's my guess (but don't do it yet until you consider the next section):

  • screw the two-speed shaft into the end of the inner liner as far as it will go.  Make sure to use one of the "starts" that spins freely, not one that binds.

  • drop the stopper into the barrel end of the head, with the silver surface last to go in

  • use your stopper rod with the prepared soft face to push the stopper up to contact the end of the two-speed shaft.

  • Holding the end of the two-speed shaft to prevent it rotating, use your stopper rod to wind the stopper onto the end of the shaft.  Stop when it starts to rotate the two-speed shaft.

  • Now, back the stopper off by turning your prepared rod counter-clockwise.  How much to back it off?  Aha, that's the $64,000 question!  Certainly "enough to ensure it doesn't jam on and rotate"!  And certainly "not so much as it will unscrew partway through the travel.  Ask Goldilocks, I guess.

  • If you happen to know what stopper distance you'd like when the slide is closed, here's your opportunity to set it.  Hold your outer head against the inner head, with the two rings at the bottom of the head touching.  Now use a rule to measure from the centre of the embouchure on the outer head to the face of the stopper on the inner head.  On the example in front of my, and with the stopper just backed off about 1/3rd of a turn, I'm getting around 20mm.  You could make it less if you want by undoing the stopper more, but not much less!

  • Now, once you have the stopper installed to your satisfaction, why not put a mark on its face showing which direction the embouchure hole is.  Then a glance down the bore or even through the embouchure hole will be enough to alert you to the stopper having rotated.  (So far, I've only dared to use a marker pen for this, but ideally something that won't rub off would be better.)

But wait!  To lubricate or not?

There's a general rule that any metal-to-metal contact requires the presence of a lubricant to prevent "metal fretting".  So I think the two-speed shaft definitely needs a good smear of lubricant. 

Given what I said above about the right amount of friction, I wondered if I should not grease the stopper cork.  But then I thought a bit of stickiness (stiction?) might actually help, so I did that too.

And finally, we definitely need the inner tube to slide smoothly inside the head, so I gave that a good smear too.  I figure also that if there is leakage between any of the sliding parts, some goup will help stop it.

But there is one place we definitely don't want to lubricate, and that is the face of the stopper.  For two reasons.  One, we depend on grabbing and rotating it by friction with our stopper tool.  Secondly, lubrication will prompt beading of the moisture from our breath, and we don't want to encourage that.  So keep the stopper face dry.

Probably anything that won't go rancid with time will do as a lubricant.  I used vaseline.

Final assembly

Assuming you're happy with all the above, go ahead, lubricate the bits and assemble.  Once you get the stopper attached with the desired degree of backing off, slide the outer head over the copper tube, and let the brass end of the two-speed screw pop through the head's end flange.  Pop on the driving flange and secure it with its pin.  The pin seems to work better from one side than the other. 

At this point, it's wise to check the operation of the system a few times by winding from one end to the other, and testing the stopper distance each time.  If it's changing, the stopper is rotating!  On the one in front of me, I'm getting a slide range of about 30mm, with a stopper distance of 16mm with slide open and 21.5 with slide closed.

Now if that all seems satisfactory, carefully clean a space to work in, retrieve the cap and the two very tiny screws from their ziplock bag, and secure the cap to the driving flange.  Wise to do this in a tray so if you drop the screws they will be findable!

Some closing thoughts.

  • If I owned a Rudall & Rose Patent Head (and I do), I would want a patented rubber-ended stopper tweaking stick to be able to carry out the operations above.  (And I have made one!)

  • We know that at least several pitches were popular in England at the time.  Older pianos would be tuned to A 430, while the young bucks at the Philharmonic were raging up around A452-455.  Voices of reason (see Society of Arts Pitch) were calling for compromise of A440Hz, but that didn't happen until close to the end of the century. It may be the case that the stopper distance for A440 that we need today might not be optimised.  With the patented rubber-ended stick, the owner might be able to fine-tune the stopper position a little to make it better.  But note - this might mean the slide is not capable of movement throughout its full range, either because it jams at one extension or because it suddenly comes loose at the other.  Up to the owner to decide on the merits I think!


Related pages

For more on this intriguing head, see

The Rudall & Rose Patent Head

Rudall & Rose 1832 Patent Head

or Back to McGee-flutes Index page...

Updated and published: 19 April 2017.   Created: some years earlier.