First notes completed
So, when I wish to tune a new bar I mark on one side of the bar the centre line, and the points that correspond to the distances that are 25%, 30%, 35% and 40% from the end of the bar.
I open Audacity and do a test recording of the bar before removing any material. This is usually way above the frequency I am looking to reach, but it is nice to have a record of where I started.
Then using a round tipped 20mm router bit which gives a nice smooth curve to my first cut, and using the 30% line as my guide, I move the bar over the router (which is mounted upwards from under the workbench). I say that I use the 30% line as a guide, but in actual fact the edge of the router curve just touches the 25% line on the higher tone bars.
Once I have my limits defined, I remove the remaining 6mm from between these two cuts.
Next I raise the router to about 11mm. I now make two more cuts using with the same router bit, making sure that the edge of the router does not cross the 40% lines. In my first early attempts at higher bars I used the 35% line as my limit but as I progressed down the scale I changed to the 40% line as my limit.
I record and analyse the frequency after every significant removal of wood. I now seem to be getting pretty close to the target frequency within a few journeys to the workbench.
When I am pretty close, within say 50 Hz, I revert to sanding. 50 Hz worth of material is quite a lot to sand away manually and occasionally I will dare to use the router to remove more, but it is easy to go over and flatten the note, which then requires removal of material from under the ends beyond the node holes and I am trying to avoid this. I generally leave the bars a few Hz sharp and will perhaps try to get exactly to pitch once the keys are all more or less finished.
So, here are my first few keys. They are upside down because they sat on the cord easier that way, given that I had not strung the keys onto a common cord as I will do once they are all made.
I open Audacity and do a test recording of the bar before removing any material. This is usually way above the frequency I am looking to reach, but it is nice to have a record of where I started.
Then using a round tipped 20mm router bit which gives a nice smooth curve to my first cut, and using the 30% line as my guide, I move the bar over the router (which is mounted upwards from under the workbench). I say that I use the 30% line as a guide, but in actual fact the edge of the router curve just touches the 25% line on the higher tone bars.
Once I have my limits defined, I remove the remaining 6mm from between these two cuts.
Next I raise the router to about 11mm. I now make two more cuts using with the same router bit, making sure that the edge of the router does not cross the 40% lines. In my first early attempts at higher bars I used the 35% line as my limit but as I progressed down the scale I changed to the 40% line as my limit.
I record and analyse the frequency after every significant removal of wood. I now seem to be getting pretty close to the target frequency within a few journeys to the workbench.
When I am pretty close, within say 50 Hz, I revert to sanding. 50 Hz worth of material is quite a lot to sand away manually and occasionally I will dare to use the router to remove more, but it is easy to go over and flatten the note, which then requires removal of material from under the ends beyond the node holes and I am trying to avoid this. I generally leave the bars a few Hz sharp and will perhaps try to get exactly to pitch once the keys are all more or less finished.
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