t first impression flute making may seem to be nothing much. Get some bamboo. Cut it to length Whack a few holes in it. Blow it. And away you go. You've got a flute.
Hang on. Not so simple. To produce a quality flute, tuned to concert pitch ( or any pitch you want for that matter) that will last a lifetime is a science and an art for sure. There are many critical steps along the way which take a long time to master.
But there are some basic steps that apply to all flute making. I'll deal with these first in this section. Later on we'll go into much more depth about the individual processes and how to make particular types of flutes.
Continuing on from the previous section we're at the stage where we have in our hands a burned and cured piece of bamboo cut to approximate length which has the internal nodal membranes pierced
Basically flute making can be divided into these sections.
Remove fully the internal node
This step consists in cleaning out the bore of the bamboo. From here on we'll take the word bore to simply mean the inside on the bamboo. The whole idea of piercing the membranes while preparing the bamboo was to allow air flow for quick drying. Obviously now we need to fully clean these out from the bore to make it as smooth and unobstructed as possible.
It was also important not to fully remove the membranes in the preparation process to ensure that the bamboo did not shrink too much. If the membranes are removed completely straight after burning then there is a chance the bamboo will shrink and/or crack. Leaving them in until stage ensures that the bamboo is now quite dry so that removal of the nodes will have negligible effect on the strength.
OK we're now ready to clean out the nodes as much as possible. We won't worry too much about making the bore glass smooth at this stage. This is left till after all the sound holes are drilled and the bamboo is bone dry. At this stage it is fairly dry but still contains some moisture.
Well there are many ways you can knock out the nodes. A bit of heavy steel rod slightly smaller than the bore diameter will do fairly well. What I use is a series of long Auger boring drill bits welded on to some heavy 10 mm steel rod in a variable speed drill.
I then put the bamboo in the jaws of a wood vice
With the bamboo firmly clamped in the jaws of the vice I drill out the nodes with a variable speed electric drill. I move the bit through the length of the bamboo. If the bamboo is very long then sometimes it is needed to drill the piece from both ends. You soon get the feel for this and it only takes a couple of seconds to clean out the nodes enough to go on to the next step.
Put in the mouthpiece
All flutes need to have a mouthpiece. As each type of flute has a different mouthpiece I will not go into the exact details of making this here. In depth details of the different types will follow.
Play the flute to see what it sounds like
After the mouthpiece has been put in the next step is to play the flute to see what it sounds like. At this stage all we're interested in finding out is the key that the flute produces with only the mouthpiece and no holes yet. Remember that in the section on preparing the bamboo we cut the pieces a node or two longer than the anticipated final length. Now after playing the flute we find out what note it produces. For this I use an electronic tuner to get the notes exact.
Cut he bamboo to just over the exact length
After the mouthpiece of the flute has been made the next step is cut the bamboo to the exact length for the particular key that we wish the flute to be in. For example say in the previous step we played the flute and found out that the note it produces was a little higher than Bb. At this stage we need to decide what key the final flute will be in.
By the way the key of the flute is the note produced when all the sound holes are closed. And this is just equivalent to the note produced when no holes have been drilled yet. Now because the note the flute produces is in exact proportion to the length of the bamboo we can now trim sections off the end till we arrive at the key we wish to flute to be in.
Depending on the quality of flute we are making this step may be a bit more involved than what I have described here but for a basic sort of flute this procedure is OK. The fine points of cutting the bamboo to exact length will be dealt with in detail in a later section.
Drill the sound holes
Once we have cut the bamboo to the required length the next step is to drill the sound holes. There are many ways to drill the sound holes. Some people like to burn them in with a hot poker or something like that. Personally I like to use a razor sharp dowelling type of drill bit set in a drill press. With this method there is no risk of splitting the bamboo and is very quick.
Before we drill the sound holes we need to know where they go. So we mark out the centres of the holes along the bamboo at the places where we will drill. I just use an impermanent felt pen so if we slip with the marking it is easy to wash off.
Now the exact positions of the holes will depend on a number of factors, the main one being the scale of the flute. There are many different musical scales e.g. major, minor, pentatonic etc. The positions of the holes will vary according the scale of the flute we wish to make. Again this will be dealt with in detail later on.
With a bit of experience it's possible to drill all the holes in one go. However because of its nature each piece of bamboo is different. Occasionally you come across a bit of bamboo that just does not want to "behave". In this case it is better to drill the holes one at a time. First of all you mark the positions of the holes according to the scale of flute you wish to make. Then you drill the bottom hole closest to the end of the flute.
At this point you play the flute and see how far the pitch differs from the "theoretical" note you expect it to produce. If the note is what you expect then you drill the next hole. You play the flute again and hear the note. If you find that the pitch is a little lower or higher than expected then you must make adjustments to the position and size of the of the next hole to compensate for this discrepancy and so on.
The process of making these adjustments to the size and position of the holes is called "Tuning" and is a fairly advanced technique which will be covered in depth later also. You continue this process of playing drilling and tuning until all the holes have been drilled and you have a flute that is in the pitch and scale that you want.
By the way don't let anyone tell you that a bamboo flute cannot be tuned exactly to concert pitch. Bamboo can be tuned exactly. This is why my flutes have been so successful. A musician can play one on stage or in a recording studio and be in pitch.
Leave the flute to dry out more
After the holes have been drilled it is best to put the flute away now for a few more days in a warm dry environment to dry out finally. This won't take long now that the holes have been drilled and there is plenty of air flow.
Polish the Bore
When you are satisfied that the flute is completely dry you can now polish up the bore to take out any remaining leftovers of the nodes. The degree to which you do this depends on the quality of flute you're making. If it is a cheap flute then you can just tape a bit of heavy steel wool onto the end of a rigid rod and by hand remove most of the excess node from the inside.
However if it is a high quality flute you're making then the process of cleaning out and polishing the bore is more involved. For this I use a couple of tools. To grind off the remains of the nodes and to shape the bore if necessary I use a rasp bit on a steel rod. For sanding the bore I use a tool that I've devised myself. All the details of this procedure are in the section on shaping the bore.
Seal or Oil the Bore
Once the flute is completed the bore needs to be treated somehow to preserve the bamboo. Remember bamboo is a woody type of material that has a grain. If not treated the inside will deteriorate over time especially since a flute is a wind instrument and is exposed to a lot of moisture through playing.
For a cheap flute it is OK to just oil the bore. You can use almost any oil as long as it will not go rancid over time. I've had good results with boiled linseed oil. You can get it in any hardware store. A good way is to tape up all the holes leaving just the bottom of the flute open. Place your hand over the bottom opening and pour the oil in the other end of the flute.
Invert the flute a few times and swirl the oil around so that the entire bore is thoroughly coated with the oil. Then let the oil drain out onto a container. You can reuse the oil again and again. This will make the bore very water resistant. It's a good idea to repeat the process every now and then though
For more expensive flutes the bore needs to be completely sealed so that it is totally waterproof. The method I use is similar to oiling the bore except that I use a high quality exterior type of polyurethane varnish. You have to be a lot more careful with this than with oil. It is extremely messy if spilled and hard to clean off the excess. With oil if you spill it you can just wipe it off easily with a rag.
To achieve a mirror like waterproof hard gloss finish in the bore you need to apply a few coats of varnish letting it dry after each coat and giving it a fine sand each time.
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