Tone Hole Leveling

Our finishers spend quite a bit of time padding flutes -- making sure that the pads are flat, shimmed, and level in the keys.  However, if the tone hole crown (top of the tone hole) is not level, all of that hard work would go to waste!  So, one of the most important steps in the finishing process is leveling the tone holes.  This process is done with both drawn and soldered tone holes. 

As with many steps in the finishing process, each finisher will have his/her variation on technique, but Karl Kornfeld demonstrated the process to us recently.  He first takes a magic marker to mark completely around the top of the tone hole.  Karl uses a green marker, although he said that any color would work.  He prefers not to use blue since the protective tape used on the flute is blue.  He then takes a small piece of a flat file and wraps it with a piece of 1200 grit sandpaper.  The flat file provides a flat surface for the sandpaper to work with in the process.  He then takes the wrapped flat file and gently sands the tone hole crown until the green marker ring disappears.  Karl shared, "If it's done correctly, it looks like a silver ring that is glowing green."  Glowing?  Well, in other words, because the tip of the magic marker is wider than the tone hole crown, a bit of marker will remain inside the tone hole -- which gives the "glow" after the green marker on the crown is sanded down.  After sanding the crown, if it looks like the silver ring is not complete (spots of green still visible on the crown), that means that there may be a low spot.  In this case, the crown must be leveled a bit more to make it flat.  Karl said that the lowest spot on the tone hole crown determines how much leveling needs to be done. 

Obviously, all this hand work takes extreme care and expertise.  The exact amount of pressure to use and actual technique comes from much practice.  As Karl mentioned, this process is extremely critical for seating pads properly -- and for making sure the entire flute mechanism fits and functions as it should as well!

Marking the tone hole crown.

Crowns marked all the way around.

Flat file

Flat file wrapped in 1200 grit sandpaper.

Leveling the tone hole crown by sanding.

Green ring gone (silver ring "glowing green" now).

Green marker left on this ring shows a low spots.

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.

The Bamboo Flute

Verne Q. Powell was a man of exquisite talent and ingenuity when it came to building flutes.  We've seen the craftsmanship of instruments he built from precious metals and wood, but there is one particular flute here at the Powell facility that is quite unique -- the bamboo flute. We recently found more information on this flute in our historical archives:

The "Bamboo Flute," Powell number 392,  is a Boehm Flute made in 1940 of a Bamboo walking stick that Mr. Willis J. Abbott brought to Mr. Powell on a trip back from China.  Mr. Powell then turned the walking stick in to a flute and gave it to his good friend William F. McKenzie. The flute is pitched in D and features engravings of monkeys along the back (see photo detail).  The top of the headjoint has a silver cap, which is engraved with the following:

“Friendship Flute

Made for

William F. McKenzie

From a Chinese Cane

The Gift of

Willis J. Abbott

Verne Q. Powell

Boston

1940”

Undercutting Tone Holes

You may have heard the term "undercut tone holes" or have read about "undercutting tone holes," but what exactly does that mean?  We spoke with flute finisher Karl Kornfeld and repair technician Rachel Baker about undercutting.  Rachel shared with us that undercutting tone holes is something that is fairly recent.  Both soldered and drawn tone holes can be undercut, although soldered tone holes would tend to have more undercutting.  Why is this?  Well, essentially, with soldered tone holes, a hole is cut into the flute body, and then then "tone hole" is soldered onto the body with the inside edges of the hole flush with the actual hole in the body.  Because the tone hole is soldered straight down onto the body, there could be sharp edges where the tone hole meets the body.  These sharp edges can cause turbulence inside the body and need to be rounded.  The rounding of these edges is what is known as "undercutting."  Less undercutting is needed on drawn tone hole flutes because the tone hole is formed by pulling metal up from the body.  Because the metal is not pulled exactly in a straight line, there is already a bit of rounding on drawn tone holes.

Undercutting is an extremely delicate step that takes care and precision.  If there is not enough undercutting, the player might feel more resistance when playing.  If there is too much undercutting, you can lose focus in the sound and definition between notes.  As Rachel reminded us, as air travels through the flute, there still need to be nodal points for the air as it travels.  Too much undercutting can disturb the air flow.  We've included some photos of two tone holes on a drawn tone hole flute.  One hole has been undercut, and the other has not yet been undercut.  It's difficult to see, but the undercut tone hole has a bit more of a reflection on the edge of the hole in the body.  The other tone hole is a bit more "'dull" around the edge.  Coincidentally, we caught up with a former Powell flute finisher who is now working on saxophones with soldered tone holes.  The tone holes are soldered with the same process that Powell uses on its soldered tone hole flutes.  Because the saxophone tone holes are so much bigger, it's much easier to see from that photo the difference between the undercut tone hole (smooth around the edge) and the one that has not yet been undercut (rough around the edge).

Many older flutes do not have undercut tone holes, so if yours does not, it's okay.  There are many types of flutes for many types of flute players!  If you have additional questions, always remember contact your authorized repair technician.

Red arrow points to undercut tone hole, orange to tone hole that has not been undercut yet.

Close-up of tone holes (top, undercut and bottom, not undercut)

You can really see the difference with these soldered saxophone tone holes.  Red arrow points to undercut.  Orange arrow point tone hole yet to be undercut (you can really see the rough edge).

B Foot or C Foot?

We recently came across a Powell Aurumite Conservatory flute in the testing room, and something seemed a bit different...  The footjoint seemed a bit "shorter" and seemed to be missing a tone hole.  Was this a mistake?  Of course not!  It was simply a C Foot flute.  With Powell Flutes, every model is available as either B Foot or C foot.  This includes, Signature, Conservatory, and Custom models.  In fact, there is an option to buy an additional foot for the custom flutes.  So, for example, if you were to by a Custom with a C foot, you could purchase an additional B foot as well.  Powell Sonaré flutes are available as B foot or C foot models, which are actually identified by the first letter of the model.  You can see a listing of these models on the Powell Sonaré page of the Powell website.  You will notice codes for various model numbers.  If the code begins with a C, it's a C foot -- if it begins with a B, it's a B foot.  Examples would be CGF and BGF.  A CGF would have a C foot, inline G, and French cups.  The BGF would have a B foot, inline G, and French cups.

So, what exactly are the differences between a C foot flute and a B foot?  Well, the C foot, as you can see in the photos, has a range that extends down to C.  With this range, there are only two tone holes on the footjoint, no B key, and no gizmo key.  A B foot flute would have a range that extends down to B, so it would have three tone holes on the footjoint, a B key, and (on Powell flutes) a gizmo key.  The gizmo key helps facilitate the high C -- you can read more about its history in our previous post on the gizmo key.  However, B foot models of Powell flutes are also available without a gizmo key.  Because a C foot flute has less physical material in its construction, it will also be lighter to hold and will be priced lower than a B foot.  In the U.S., the majority of Powell sales are for flutes with a B foot.  In the UK, many players prefer the C foot.  Regardless of your choice, Powell has the option with each model (as mentioned above).  There are also cases available from Powell for either a B foot or C foot flute.  The photos below show Aurumite Conservatory C foot and B foot models.

C Foot -- two tone holes, no B key, no gizmo.

Close-up on C footjoint.

B Foot has three tone holes and additional keys.

Red arrow points to gizmo key, yellow points to B key.

The "Play-In"

Preparing shims before the play-in

The assumption that musical instruments are play-tested before they leave the shop is accurate, but at Powell Flutes, the process is a bit different.  We recently caught up with flute finisher Karl Kornfeld, who was getting an Aurumite Conservatory ready for its "play-in."  According to Karl, the "play-in" is actually part of the finishing process and not a "play test."  It is, however, the first time that the instrument is played.  So, what exactly does all this mean?  Let's take a look...

Karl had just finished the flute from a mechanical perspective.  He had all the mechanism work completed, finished padding, and was now going through to make small adjustments for the "play in."  Theoretically, once all the "parts" are built onto the flute, and if all the steps are followed properly, it should work perfectly, right?  Well, in theory, that is correct, but there may be some slight adjustments necessary for it to be comfortable and ready for the "play-in."  So, before it goes over to a professional for the initial play-in, Karl checks the flute.  He makes sure the mechanisms are all the correct "weight," tests spring tension, checks for leaks, and makes any additional adjustments.  Now the flute is ready for the "play-in."  The finisher knows that this is an important part of the process, because after the initial playing, the flute will "settle."

Fine-tuning another shim

We asked our testing manager what steps she takes to "play-in" the flute.  She prefers to perform music that will cover the full range of the flute, such as French pieces or modern repertoire.  After she plays the flute, it begins to settle from the action of being played, and it is then closer to being ready for the customer.  Of course, after she plays the flute, she must evaluate it to see if (in its more "settled" state) it needs any additional "tweaks."  Karl knows that there will undoubtedly be additional adjustments after the play-in.  Then, once those are completed, it is ready for a final play test.  When it passes another evaluation from the play-test, it is ready for the customer.

Checking spring tension and mechanism "weight"

Checking for leaks

Checking for Leaks

Feeler gauge with Mylar

If you walk through the finishing department at Powell, you will undoubtedly find our finishers "sweeping" a little stick around each pad several times -- or at least this is what it may look like from afar.  But, this small, very manual device is actually a feeler gauge -- and the finishers are checking for leaks.  You have probably heard a few repair technicians, fellow players, and teachers talk about leaking pads, and our finishers make sure that there are no leaking pads on the flutes that they are finishing.

So, what exactly is a leaking pad?  Well, it can seem a bit misleading, since it's not exactly the same as a tire leaking air.  When checking for leaks, it's actually the pad seal that is being tested to make sure there are no leaks.  In simpler terms, when the key cup closes and the pad covers the tone hole, are there any gaps between the pad and the edge of the hole?  The answer should be no, because we all know what the result would be... You see, the air you put through the flute could escape or "leak" through if the pads are not sealing against the tone hole, and you would find it difficult to play the notes you are expecting to come out! 

Using the gauge around the pad to check for leaks

Finishers and repair technicians have different techniques for checking for leaks, but we caught up with finisher Karl Kornfeld at Powell.  He showed us two feeler gauges which were both small "sticks" with a feeler paper on the end.  One gauge used cigarette paper, which is .001 of an inch thick.  This is the traditional type of gauge that you may have seen your technician use or that you may use yourself.  The other gauge, which is the one Karl and the other finishers use, has a piece of Mylar at the end.  Mylar is .0005 of an inch thick, which is definitely thinner than the cigarette paper and (therefore) more precise in detecting leaks.  Karl uses a general "sweep" around the pad with the gauge to see where there may be leaks.  He then goes around the pad clockwise, drawing the gauge out to check various spots.  He says the pressure should be even as you check, and you should draw the gauge out with the same motion -- just to keep everything consistent.  Although he usually begins checking pads with a "sweep," in the video below, you will see him draw the gauge, then circle around with the "sweeping motion," and repeat the drawing motion.  Oddly enough, he also told us that Mylar is the same material used in Pop Tart wrappers!  Obviously, the Mylar on the feeler gauge is much, much thinner --- thank goodness.