The role of the overlap

January 21, 2010

Yesterday someone posted about the overlap as being a function of the tie.

The overlap functions in many ways than the mere “afterthought” that it seems to be. First of all, the overlap is traditionally done with the top blade slipped to the right, although I will admit that it probably doesn’t matter what side you slip it to. What DOES matter however is the direction that you tie the reed with the string. If you slip to the right, you should be tying clockwise (if you’re looking straight down the reed). If you slip to the left, you should be tying counterclockwise. The idea is so that the torque of the string should be pulling the blades back together, not apart. This prevents the blades from slipping too far, but also helps the edges of the blades grip against each other better, creating a better seal.

The second function of the overlap is a structural one. Once you have an overlap that grips together very well, you can scrape it differently, specifically I always scrape the left rail in the windows thinner than the right rail, and sometimes the left rail in the heart as well. I also scrape a hair more out of the left window, and offset the spine in the windows slightly to the left so that it is closer to the overall “center” when you look at the entire outline. I’m not sure how to describe these effects, but the best way to know is simply to experiment with it.

The last function has its roots as far back as Sprenkle. When the reed is in your oboe, if you angle it clockwise 15-20 degrees (assuming your reed is slipped traditionally), the compression of your mouth will push the blades open. However, if you tilt the reed counterclockwise, the naturally compression of your mouth pushes the blades closed.

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4 Responses to “The role of the overlap”

  1. Figuring out my overlap problem last year was one of the best things that ever happened to my reed-making. What seems like such a small thing, and is actually hugely important.

  2. Jeremy said

    One of the interesting things about the overlap is that standard European scrapes don’t have one. The two blades are set directly on top of each other. There is even a tiny clamp you can buy that holds the blades in the “perfect” position for tying.

    I don’t like the “torque of the thread” explanation. Rather, if the overlap were to be the wrong way, every additional wrap (as you wrap up to the top of the staple) is pulling the overlap further and further apart. If the overlap is set the correct way the lower blade sets into the upper one, this natural stop preventing the overlap from developing any further.

    While the blades must be identically shaped for all scrape styles, it seems to me that the overlap-wrap is a tiny bit more forgiving than the European wrap, where there is absolutely no tolerance for error. Which is why the straight shaper is gaining popularity overthere.
    A straight shaper forces the knife edge to cut the cane at a particular angle and there can be no tendency to angle over the edges, which can happen with a traditional folded-cane shaper.

  3. Annie said

    Cooper! Are you ever going to blog again?!? I need some good oboe reeding material!

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