Fitting a Footjoint - Part II

We were upstairs on the production floor earlier this week when we ran into flute finisher Lindsey McChord fitting a footjoint.  We had a previous post on footjoint fitting (you can see the post by clicking here), but that post detailed how to fit a footjoint when the body tenon was too big.  So, what happens when the tenon is too small?  We had the chance to find out!

When we caught up with Lindsey, she had a Conservatory with a body tenon that was just slightly too small for the footjoint.  Additionally, Lindsey felt a bit of "rocking" when she placed the footjoint on the tenon, so she needed to expand the body tenon just slightly.  To do this, she placed the body on an arbor and began burnishing the tenon.  Burnishing is a process where the metal of the tenon is pressed against the metal arbor.  By doing this, the tenon metal expands from the pressure.  However, the pressure has to be very light, and you have to exert equal pressure all around.  Because the process is so delicate, Lindsey began by burnishing the tenon in about three spots.  She then tested the fit, and it was still a bit loose.  The initial three burnished spots on the tenon were visible as lines that had a bit of a "matte" finish.  Since she could see the initial marks, she then burnished the tenon in a few more spots between the areas that were burnished in the previous step.   Once again, she tested the fit.  It was good -- even a bit on the tight side.

Now that the fit was almost perfect, there was one more step needed to remove any marks from the burnishing process and get a perfect fit.  To do this, Lindsey used very fine-grade sandpaper on the tenon.  The rough side of the sandpaper is good for removing slight bits of material, so Lindsey sanded a bit with that side of the paper.  However, she also used the opposite, smooth side of the sandpaper to smooth out any marks.  Then, she took a tissue and wiped both the outside of the body tenon and the inside of the footjoint.  This helped remove any debris that might hinder a smooth fit.  After this, she tested the fit of the tenon once again, and it was perfect.  She then added the final step of a bit of polish to shine and smooth the tenon, and it was ready!

Recapping the process, it may seem simple enough, but it truly takes great skill and patience.  Every step in burnishing must be done in very small, light increments -- but the most important skill is the ability to feel the fit.  It's much more than a matter of  "too tight" or "too loose."  One must be able to assess the fit on many levels and feel the slightest imperfections.

Checking the fit of the footjoint.  It is a bit loose and "rocking."

Placing the body tenon on an arbor.

Burnishing the tenon with a burnishing tool.

Burnishing marks -- these serve as a guide, too, for additional burnishing.

Checking the fit again.  Just a tiny bot too tight now.

Sanding the tenon to remove marks and make it just a bit smaller after burnishing.

Using the opposite side of the sandpaper to smooth out the tenon.

Cleaning out any residue in the footjoint.  This was done on the tenon as well.

Checking the fit again -- perfect now.

After polishing, the tenon is shiny and smooth.  Done!

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.