Broken and Missing keys, Impossible pads

A lot of perfectly good, indeed, sometimes unique and exciting original flutes are rendered unusable by broken or missing keys, or by something as seemingly insignificant as pads no longer available.  We'll look at a few examples of how that can be overcome.

Clinton's Broken Long F

The long F key on the flute below has been broken at the hinge tube.  Long F and upper C keys are more often broken, being longer and more prominent than most.  Post mounted keys have a pronounced weakness where the hinge tube passes through, and we can see that was what failed in the two cases below.

Broken long F key and the G# key from the Clinton flute

Clinton's Missing C key

The very long upper c key was totally missing on this flute.  Again, we can tell it was failure at the hinge tube, as the hinge tube was still there, waiting patiently on the axle between the posts.

The main challenge in reconstructing this key was coming up with a cup that would look like the other very distinctive original cups.  There was also a matter of tolerances - the cups were set into their seats with a clearance all round of about 0.075mm - about 3 thousandths of an inch!

Accurate measurements were taken of a similar cup elsewhere on the instrument.  A special punch was made up to set the internal diameter and provide the general shape.  A disk of slightly too thick silver was annealed and punched over a lead block to take up the shape.  The punch and disk were then mounted in the wood-lathe and metal spinning techniques used to form the skirts of the cup.  Excess skirt was parted off, and a hand-held tool used to reduce the OD to the desired diameter.  The same tool was used to cut the inset ledge around the cup.

While the use of the punch had formed the general shape, it could not produce the sharp-tipped atrium-shaped dome on the top of the cup.  The cup was temporarily secured to the end of the punch with Loctite, and the shape produced by hand turning with a fine gouge.  The cup was then removed using heat to weaken the Loctite.

The shaft and touch was made up from sterling bar to best resemble the remaining keys.  Great care was needed to attach the cup to the end of the shaft so that the up would fall freely within the small tolerance available at the seat.  In the event it worked first time.

Above: The body keys of the Clinton flute, showing the replacement c key (very long key near bottom) and repaired Long F (long key at top).  Note the extraordinary lengths of these two keys needed to span the very wide scale of the instrument.

(The brass insert in the ring key second from the left is an experiment to determine the most likely to be correct form and dimensions for a missing insert.)

Thin Card-backed pads

One of the challenges facing the restoration of the Clinton flute was the unavailability of the very thin card-backed pads used on this 1851 model instrument.  Modern pads are well over 3mm thick and are not available in the sizes needed for such flutes.  Piccolo pads are sometimes the right thickness, but far too small.  

The problem with using pads that are too thick is that the pad jams on the hinge side of the cup a long time before it closes on the other side.  You can get away with pads that are too thin, but never with pads that are too thick.

Carefully dissecting the old dried pads we find they are made from:

  • a layer of card, about 0.3mm thick

  • a layer of felt, about 1.5mm thick

  • a fine leather cover, about 0.2mm thick

The end result is that a pad of about 2mm thickness is needed. Taking that view that if they could make these pads in 1851, surely we can make them in 2002, I set out to make a new set.   

For the very thin backing card, I used an old playing card.  The felt and skin came from new clarinet pads of larger diameter.  Getting the size right meant turning up a wad punch to the size needed to punch out the disks of card and felt. 

The only slightly tricky part is assembling the pads to provide a smooth taut skin.  Like most things in life, it's only tricky until you know how!  After a few experiments, I found the following technique the most satisfactory.

Place the skin face-side down on a moistened cloth.  This keeps the skin damp during construction and helps anchor it on the work surface.  Place the felt and then the disk on top, centered on the skin. Hold the parts down using a piece of rod in the centre of the disk to prevent everything moving about.

Use an artist's paintbrush or something similar to run some craft or similar thin glue around the back of the disk near its edge.  With tweezers, pull an edge of the skin onto the glue at the top, then do the same at the bottom, left and right sides.  Now do the same with the four pieces left sticking up.  With a rounded tool, go round the pad, rubbing the skin inwards and downwards until it lies flat all round and the glue has taken.  Pick up the pad, rolling it around gently between the fingers to iron out any remaining bumps around the periphery. 

As soon as the pad is removed from the moistened surface, it will stretch tight and can be installed without any further delay.

From the left, in the image above:

  • an original pad

  • an original pad open to reveal the card below and the skin above

  • the felt from that pad, and

  • a modern hand-made replacement of the required dimensions


The other type of pads that cause problems in replacement are the purse-pads originally used with saltspoon keys.  Again, making these presents no real problems, and they work far better than trying to press a modern pad into service.  Next time I do some, I'll take some pics for this page.  In the meantime, if you are caught short for some, send me an email and I'll tell you how to proceed.


While restoring old flutes presents some interesting challenges, there is probably very little that cannot be done if the instrument warrants it.

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