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Friday, April 5, 2013

Crafting a Slit Drum

by Chris Bittner

Slit drums are a fascinating and ancient percussion instrument, common to cultures around the world. The basic design of a slit drum is quite simple; a section of log or tree branch with a long slit carved along its length, through which the middle of the log is hollowed out. The slit stops short of reaching the ends of the log, so that the ends are left intact. The drummer will play the slit drum with two sticks, striking near the center of the log, and on either side of the slit. Generally, one "playing area" has been carved thinner on the underside, giving that side a lower tone than the other side. Slit drums vary in size from quite small (a foot long and four inches in diameter) to full size logs.

I have been fortunate to see a few large slit drums in museums which were beautifully crafted. One that I remember in particular was carved over its entire surface with carvings of animals. This slit drum was African. At the ends of the slit on the top of the drum were fair sized square holes that probably serve to enhance resonance as well as giving the carver greater access for the hollowing process.

A few years back, my friend and teacher Dan Trevino visited Guinea and brought back a set of three "krins." These were small slit drums, one each small, medium and large, with the largest perhaps 20 inches long. The krins were to be played by three different drummers, each playing a different part, therefore playing specific songs. The krins were carved with three slits: one wide one in the middle, and two narrower ones on each side of the wide one. The wide slit allows access to the middle of the log for hollowing, while the two outer slits create two separate "tone bars." Additionally, one of the narrower slits is shorter on one end than the other two slits, giving its tone bar a higher pitch. The ends of the log are also used. In fact, the sticks tap out a continuous steady beat, and whichever musical spaces are not being played on the two tone bars are being played on the "side notes," as we called them. As you can imagine, it takes some practice to coordinate the continuous left-right-left-right pattern with the proper notes of the song.

Making a Slit Drum

After playing krin music for some time, I made several krins. The first krin I made was from a piece of Elmwood, fresh-cut from a living tree that was taken down. It was about 15 inches long and 4 inches in diameter. I know from my carving experience that green wood is softer and easier to carve than dried wood. Of course, it is also true that the carved green piece is likely to crack, to some degree, as it dries. As you may know, wood shrinks as it dries. As the outer portions of the wood dry faster than the inner portions, stresses develop, and cracks open up to relieve the stresses. But I decided to carve the krin from green wood, reasoning that I may get lucky and have few cracks develop, and that I could always dry some wood and try dry wood later. 

It is worth noting here that the subject of drying wood without cracks is quite involved. But if this task is before you, you are well advised to read what you can about it to increase your chances of success. An excellent resource is Understanding Wood by R. Bruce Hoadley, considered by many to be the most comprehensive book on the subject. It becomes very scientific at times, but is very friendly to the novice (myself included).

I brought the piece of elm into my workshop and debarked it. I chose the side that I wanted to carve the slits on and marked the outlines of the 3 slits. The middle slit would be about 1 inch wide and stopping about 2 inches from the ends. The second slit would be 3/8ths of an inch wide, and the same length as the middle slit. The third slit would also be 3/8ths of an inch wide, but shorter on one end than the first two slits by about 2 inches. The tone bar on this side will be the higher note of the finished krin.

The task is to carve out the three slits and the entire inside of the log piece, creating two tone bars and a resonation chamber. I began by drilling holes along the slits, the same size as the width of the slits. I went maybe halfway into the log. Then I continued with carving gouges until I had the slits basic shape opened up. Carving gouges are a straight handled tool with a "U" shaped cutting edge, used by pushing or tapping with a mallet. They come in all sizes. I continued using the gouges and the drill to remove wood from the middle of the log, working through the large, middle slot. As you can imagine, this is rather difficult. One thing that will help is to secure the log to a workbench. I did this by wrapping a rope around the ends of the log, and putting the two rope ends through holes in the workbench, one hole at each end of the krin. I tied the two rope ends (from one end of the krin) together to form a loop, then put a stout piece of stick through the loop, then twisted the stick to pull the krin down ever tighter against the workbench. I pounded a nail into the table to secure the stick. Repeat for the other end. Now the krin wouldn't move as I carved it.

Eventually the inside was carved out to my satisfaction. I put the krin in a relatively humid place to try to allow it to dry slowly, to avoid cracks. But as it turned out, the krin split wide open radially from the middle slit to the pith of the log. Interestingly, the krin sounds fine anyway! But it sure doesn't look good.

For my second krin, I tried using a piece of sycamore wood, larger than the first krin. I drilled a hole into each end of the krin, straight into the pith. I reasoned that this would help to remove some of the stresses that cause cracks. Then I carved the krin as before. When finished, I put a hose clamp around each end of the krin, maybe one inch from the ends, and tightened them down very hard. I hoped that this would physically stop the cracks from opening. I noticed that it was necessary to tighten the hose-clamps everyday to maintain tightness, since the wood was drying and shrinking continuously. In the end, it worked! I dried it without any cracks, and finished it beautifully with oil finish and paste wax. Several more krins were completed with good results this way.

All of this causes one to wonder how they're made in Africa. Although certainly the carvers there don't have all the same tools I have access to, I'm sure their methods are simpler. I believe that it is also true that some woods are more susceptible to cracking than others.

I enjoy working big. It occurred to me awhile back that I could make a similar instrument by cutting a large log section in half straight down the length of the log, then carving this piece out on the inside, leaving a sort of a "half-cylinder". I imagined mounting this half-cylinder on a thick board to create a base for it. Then I would carve the slits, and finish the drum. Then it came to pass that I cut down a dead walnut tree. When the tree fell, it was revealed that the tree was hollow in a four-foot section at the base of the tree. Normally, this section would have become an ashiko-type drum, but this section had split in two in the course of the tree's falling. So there I had my two half-cylinder pieces, having come right to me! I have dried the two pieces and begun work on them. I'm sure they will make fine slit drums.

I hope you have enjoyed reading about my slit drum adventures! I hope you will be inclined to make your own percussion instruments. Enjoy, Chris Bittner 

Chris Bittner developed an appreciation of wood at an early age, as well as a talent for working with it. Later in life he learned the joys of rhythm and community drumming. In 1999, Chris made his first djembe, when it became magically apparent to him that drum making could be his full time endeavor. And so, DrumWorks was born, in an effort to work at what he loves, and to provide people with the instruments so that they could enjoy rhythm as much as he does. You may learn more about Chris and DrumWorks at http://www.skillpages.com/drummer/akron-united-states/chris.bittner.



2 comments:

  1. Greetings Angelo,
    Thank you for commenting on my post. I hope all is well with you and your circle.
    In Peace,
    Michael Drake

    ReplyDelete