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Making the Bars
I knew nothing about this until I got Jon Madin's book, Make Your Own Marimbas. The book is wonderful and explains everything you need to know about this project. I highly recommend it. All of the design principles here are Madin's, not ours, although the modifications here are our ideas.
CHOOSING WOOD. When we were faced with the decision of what wood to buy, we knew only that it had to be a hardwood, and that we needed about 33 feet of it. So I spoke with Gilberto Serna, world-renowned marimba maker of Century Mallets here in Chicago. He confirmed that rosewood is what the best marimba bars are made of; his second choice of wood would be bubinga; and after that he would choose mahogany, but he had reservations about mahogany, because it was too soft. And all of these were quite expensive. So my husband and I went to the wood store. Rosewood indeed was way too expensive. (Like lobster, the price list read, "at market price.") Bubinga was less, but still quite expensive ($10.32/board foot). Mahogany was up there, too. So we talked with the guys at the shop, and they offered to give us some other pieces of hardwood to make a sample bar or so out of. We took home some oak, maple, and at their suggestion, some padouk (sometimes spelled paduak).
|The winner by far, in ease of working, sound, and good looks, was the padouk. We ended up spending about $110 for the padouk for the bars. The padouk planks, when cut, produced bright orange sawdust which smelled spicy and stained our clothing.|
But the bars were beautiful. Interestingly enough, since then we have noticed that some professional marimba dealers have padouk bars on their less expensive models! I guess we lucked out. The bars you see above are the natural color of the wood, except the far right bar, which has been oiled with a clear finishing oil.
MAKING THE BLANKS. Each bar had to be cut from the raw wood to a certain length; then a hole was drilled through it at a point 2/9ths from the end (see bar on left, above). Then the center point was determined, and a cut was made halfway through the thickness of the bar (second from left). Then, the underside of the bar is carved (see bar in middle), up to the third point on each side (see fourth bar from left). In Make Your Own Marimbas, the dimensions of each bar and its 2/9ths point are specified. We cut each bar "blank" to the appropriate length and width; then we drilled a hole at the 2/9ths point (the nodal point) for the nail on the frame to go through. These bars are held in place like Orff instruments are, by a nail which pierces the bar at the center of the 2/9ths point. The bar then rests on rope threaded through the screw eyes, shown below. .
|Regular marimbas have side-to-side holes in the bars, so that the bars end up being threaded like beads on a cord which holds them in place. This is not the case with Orff instruments; quite often bars will be removed here and there, to create a pentatonic scale, for instance. The single nail holding the bar in place makes this possible. It does mean, however, that the bars will bounce off if they are played hard.|
WAYS OF CARVING BARS. The bar planks need to be carved on the underside to lower the pitch to the desired note. Jon Madin describes different ways of carving the bars, including chiselling, belt sanding, or using a bandsaw or a table saw, or woodcarving attachments on power tools. In my opinion, the safest way is to chisel out the underside. This is done fastest when you have a group of people carving bars all at once. I started out with the idea of having the children at my school help with the bars; but for various reasons, insurance and timing being chief among them, my husband and I ended up doing the whole thing ourselves.
For speed's sake, we ended up using the table saw method, dragging the bar across the low-set spinning blade. This is a very dangerous method, but we did it this way because my husband is a skilled and accomplished woodworker and he knew how to take precautions to minimize the danger. Because it is so dangerous, I DO NOT RECOMMEND THIS METHOD; it is easy to lose fingers with table saws. My husband alone did the table saw carving, and he is extremely cautious when working with power tools. When using power tools to remove wood, it is also very easy to remove too much wood too fast, making the bar too low in pitch. I urge you to use the chiselling method if at all possible.
TUNING BARS. We bought a chromatic tuner to test the bars with. In Make Your Own Marimbas, there is a good description of how to tune bars. Basically, taking wood from the underside middle of the bar lowers the pitch. Taking wood off of the underside at each end raises the pitch again. The wood is carved off in a curve, making an arch-shaped hole.
|All the while, one must constantly check the pitch of the bar with a chromatic tuner (see tuning bars, below). Eventually the finished bar appears like the last bar above, which has oiled and labelled with adhesive letters from the art supply store.|
||One can just tune testing the fundamental pitch (the basic note, shown on left), or one can simultaneously tune testing the overtones (the harmonics, shown on right). If your ears are sensitive to pitch, I highly recommend doing both fundamental and overtone tuning. We didn't worry about overtones at first, and ended up with a bar where the fundamental was a half step off from the overtones. YUCK!! It had a horrible after-ring to it. We were able to salvage the bar, but it sure sounded awful at first.||
An important note: when we first carved our bars, it was in July, outside, at a humid 90 degrees. The bars lived in our garage. They were at pitch outside, but when we took them inside (air-conditioned 70 degrees), suddenly they were all sharp! Likewise, when the bars were outside, in the morning they would be at a different pitch than during the heat of the day. What this told us is that the bars should be tuned in a place that is the same environment as where the instrument will be used when it is done. It could be that different woods are more or less sensitive to these changes; the padouk was very sensitive. (This is one advantage to instruments with non-wood bars - they don't fluctuate in pitch with temperature and humidity.)
FINISHING BARS. Once the bars were close to pitch (about 10 cents sharp), we sanded them to perfect the pitch and make them smooth. Then the bars were oiled and allowed to dry, and labelled with their letter name. Two weeks later, we checked the tuning of the bars again, and did some more adjustments. It has been about six months now, and I'm beginning to notice that they need tuning again - they're all about 20 cents sharp. So we will do some more sanding, and bring the pitch back down.
MAKING ACCIDENTALS FOR ORFF INSTRUMENTS. It's amazing what a little knowledge can do - now that I knew how to carve bars (see above), I used some padouk scraps to make myself some F#'s and Bb's for some instruments with the accidentals missing. I just measured the other bars on the instrument (height, width, depth, whether it's curved or flat on the top), made a blank of the same dimensions as the natural of that note, and chiselled away at the underside until I had a bar with the pitch I wanted (see the description of the process above, or in Jon Madin's book, Make Your Own Marimbas). Since these bars were for alto and soprano xylophones with smaller bars than a bass marimba, these bars were done in no time! Now I could even add some C#'s or Eb's if I wanted to play in different keys.
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