Stencils and tools
Having found wood I bought some basic tools so that I could start modifying the sound each bar made by cutting out material from the underside. However, I was unsure of where to cut. How far should the arch extend, and how deep should it go?
I still had no real answers when two things happened. Firstly I received an email from Tom Bourne in the US with whom I had corresponded before. His excellent and entertaining video on Crafting a Marimba was my primary inspiration and the best video out there in my opinion. Tom has a whole workshop of power tools and makes marimbas for schools. He was kind enough to send me the dimensions he works to to make keys. Although I was still a little unsure of how well they would translate to karagatch, I translated them from inches into metric measurements and on doing so recognised that there was a fairly clear pattern to their lengths.
Around the same time I also came across a video from RockFreakinSolid that helped me. His video explained that whatever the wood, whatever the note, whatever the length of the bar - the nodes would be found 22.5% of the way in from the ends.
I knew how to find the nodes using the salt technique but I found this a little impractical for my karagatch bars as the salt kept aligning in the wrong direction or jumping off (as I did not have a suitable instrument with which to vibrate the bar gently). This new information basically encouraged me not to try and find the nodes of every bar in this, my first and experimental marimba build. Instead, use the 22.5% rule.
Tom's measurements in centimetres basically showed more or less regular increments of change between notes. Knowing now that the nodes would be at 22.5%, I decided to round off Tom's measurements to the nearest centimetre, giving me bars that increased in length by one centimetre as I went down the scale from C6.
I should state at this point that I was not building a chromatic instrument and was only including one accidental in my scale - the F#. This would allow me to play a majority of my marimba repertoire since most tunes are written in the key of C or G. I kept the increments the same - one centimetre increase - through the F, F#, G section of the octave even though these are only semitone differences, unlike the G, A, B, C, D, E and F intervals that are all one tone different.
Now, before I set to work on the keys I made a set of dummy or template keys from some 5mm thick foam-board that I happen to have to hand. I could write on these templates and mark out the nodes, the half way mark, write the frequency and the length on them and basically pack them with information so I didn't have to keep referring to my computer in the workshop. They have proved to be really useful and I would recommend making templates like this too, from thick card if you don't have foam-board. The notes can sit on them when not being worked on and they help prevent damage and keep all the notes in order.
I still had no real answers when two things happened. Firstly I received an email from Tom Bourne in the US with whom I had corresponded before. His excellent and entertaining video on Crafting a Marimba was my primary inspiration and the best video out there in my opinion. Tom has a whole workshop of power tools and makes marimbas for schools. He was kind enough to send me the dimensions he works to to make keys. Although I was still a little unsure of how well they would translate to karagatch, I translated them from inches into metric measurements and on doing so recognised that there was a fairly clear pattern to their lengths.
Around the same time I also came across a video from RockFreakinSolid that helped me. His video explained that whatever the wood, whatever the note, whatever the length of the bar - the nodes would be found 22.5% of the way in from the ends.
I knew how to find the nodes using the salt technique but I found this a little impractical for my karagatch bars as the salt kept aligning in the wrong direction or jumping off (as I did not have a suitable instrument with which to vibrate the bar gently). This new information basically encouraged me not to try and find the nodes of every bar in this, my first and experimental marimba build. Instead, use the 22.5% rule.
Tom's measurements in centimetres basically showed more or less regular increments of change between notes. Knowing now that the nodes would be at 22.5%, I decided to round off Tom's measurements to the nearest centimetre, giving me bars that increased in length by one centimetre as I went down the scale from C6.
I should state at this point that I was not building a chromatic instrument and was only including one accidental in my scale - the F#. This would allow me to play a majority of my marimba repertoire since most tunes are written in the key of C or G. I kept the increments the same - one centimetre increase - through the F, F#, G section of the octave even though these are only semitone differences, unlike the G, A, B, C, D, E and F intervals that are all one tone different.
Now, before I set to work on the keys I made a set of dummy or template keys from some 5mm thick foam-board that I happen to have to hand. I could write on these templates and mark out the nodes, the half way mark, write the frequency and the length on them and basically pack them with information so I didn't have to keep referring to my computer in the workshop. They have proved to be really useful and I would recommend making templates like this too, from thick card if you don't have foam-board. The notes can sit on them when not being worked on and they help prevent damage and keep all the notes in order.
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