To make the flute visually pleasing I like to round most parts of it. Actually you could leave the shape as is (rectangular) and it will perfectly work …

I create a pen mark 40mm left of the SAC-exit (north) and 20mm to the right of the TSH (south). This is the part that I will not turn round because I want the top (bottom of the flue) as flat/plan as possible. I haven’t touched this area in the whole process since planing it with the thickness planer.

To make my life easier for turning on the lathe I use the router a last time in my process to break the edges. I use a 40mm diameter router bit (see picture). To completely pre-round the bottom edges. The two top edges are also pre-rounded but I skip the sound area (see 40mm and 20mm marks above). This step reduces the risk that the two blank halves will break when turning. 

Cool! It’s starting to look like flute 🙂 

I use a centering cone on the mouth hole side. On the left side (bore end) I am using a chuck to hold the flue and center it at the same time. I am using a gummi ring around the metal (see picture) to protect the wood. Be very carefull how much outward pressure is put on the flute. The glue seem might break if the outward pressure is too high. Do it just hard enough to make the flute spin and create some resistance when turning.

I use a chisel to carefully take off wood until the diameter is about 32mm which leaves a wall thickness of 3-4mm. With some wood I get into the problem of the flute “bending”/”shaking” in the middle when turning. I use my left hand to carefully touch and stabilize the flute while holding the chisel with my right hand. It’s the way I do it – having 10 years wood-turing experience – but it can be dangerous so please be carefull !!!!

The final part to shape is the mouth part. There are lots of possibilities to make it more or less pointed. I like it the way you see on the picture. Make sure not to make the walls too thin where the SAC chamber is located. Unfortunately I detroyed some flutes by turning too much wood off and “opening” the SAC to the outside.

After turning both sides (north / south) of the sound area I stop the lathe and use an oszillating sander to round the 3 sides of the sound area BUT not the top area where the bird will sit (the nest).

Afterwards I am sanding the flute on the lathe starting with 120 and ending with 400 grit. A good practice is to stop the lathe once in a while (with every grit) to hand-sand in flute direction to avoid vertical streaks and also to sand the 3 rounded sides of the sound area.

I order to create a good base for finishing and to fill the pores I use shellac based sanding sealer after the first smoothing step.

Then again sanding from 120 to 400 grit.

Now its time to hear some sound ..