Hand Shaped Corks

You've probably heard the term "hand shaped corks," but what does that mean?  Are these corks on your flute really shaped by hand?  Well, the answer is yes!  We recently caught up with flute finisher Karl Kornfeld to take a look at the process.

Corks are used on the trill keys, G# key, and D# key.  Powell receives a supply of corks in the shape of small "barrel-type" pieces -- similar to a cork from a wine bottle.  One cork piece will be used for the 4 keys mentioned above.  The cork is first cut into quarters.  Karl prefers to take one of the quarters and then cut that quarter in half for the trill keys.  This helps with consistency and allows for these corks to (aesthetically) "match."  When we caught up with Karl, he was working on a D# cork.  For this key, he uses one of the cork "quarters."  He uses contact cement on one side of the cork and the back of the key.  Then, he presses the two together and holds them (with the help of some equipment) until the glue is dry (about 10 seconds).

Now the shaping process begins.  The cork must be shaped so that the key opens to a standard measurement that Powell uses on their flutes.  A cup height gauge is used to periodically check the height of the key cup opening as the cork is shaped.  Finishers use a combination of double-sided razor blades and various grits of sandpaper (220, 400, 800).  The higher the grit, the finer the sandpaper.  Karl puts the key mechanism back on the flute and marks the cork in the center, where the cork touches the center of the "box" (box is the area between the sides of the ring).  He then begins to shape the cork with the combination of sandpaper and razor blades.  In the photos below, the thin strip of sandpaper is 220 grit, and the larger piece is 400.  The 800 grit is used for very fine adjustments.  He continues sanding and shaping the cork until it is the correct size and shape for the key to open properly at the calculated height -- which is critical. 

There are other mechanisms which have cork for adjustments, and for these, small slices of the original cork are used.  So, now if you hear the term "hand shaped corks" with Powell flutes, you'll know that they are truly hand shaped by our finishers!

It begins with a piece of cork.

Cork piece divided into quarters.

One quarter piece for the D# key.

Applying contact cement to cork (and then key).

Pressing key and cork together.

Holding key and cork together until glue dries.  Leather strip is used to protect key.

Shaping cork with razor.

Marking center of cork where it meets center of the "box."

Sides of cork should not touch sides of ring.

Some shaping with a 220 grit strip of sandpaper.

Checking key opening with cup height gauge.

More shaping with a 400 grit piece of sandpaper.

Finished!

Quarter cut in half to match trill key corks.

Slice of this piece used for adjustment cork.

Headjoint Show Stoppers

In our last installment of the headjoint series by Steven Wasser, we take a look at the cork assembly and crown.

The headjoint has a cork assembly and a crown at the “dead” end of the headjoint tube.  The purpose of the cork assembly and crown is to prevent the waste of the player’s air stream from going up the headjoint rather than down into the flute tube. 

Some cork assemblies have been developed using o-rings that allow the upper end of the headjoint to vibrate more.  In our experience that vibration actually diffuses acoustical energy.  We draw an analogy to high-end speakers which are often made very heavy in order to produce the purest, most accurate sound possible.  Based on this analogy we want the upper end of the headjoint to be as dead as possible so that the blowing energy creates the strongest possible acoustical wave down the flute tube.

Many headjoint makers have also experimented with the size, shape and material of the end of the cork assembly.  Each shape and material has pros and cons but, on balance, the flat disc made of plated brass or nickel silver seems to work best.

Finally there is - the crown.  This component is decorative as well as functional.  The weight, material and shape of the crown all create subtle acoustical differences.  

Cork assembly

Another view of cork assembly.  Crown screws into the threaded end.

Crowns in silver and gold (10K, 14K and 19.5K).

Underside of crown (where cork assembly attaches).