Criticality of staple dimensions?

[bobkeenan]

I was reading through past archives of the pipers review on the uilleann forum and come across a long article that Ted Anderson wrote in 1982 mostly on staples. He went into some great detail on the calculations that go into making the best staple. I think he was going for a theoretically best internal staple volume. How important is this?

I am going to try it and find out. Mostly to-date I have been making reeds with a mandrel that brad angus gave me but I have been varying staple dimensions and rolling the staple at different locations along the mandrel. But I have not done it in any scientific manner to draw any conclusions yet.

[Christian Tietje]

Hi Bob,
the staple diameter and the kind of staple cone are mostly relevant for the upper octave. The movement of the air within the staple and the chanter itself is created by the reed and goes fast forward and backward, related to the frequency of the tone. Therefore according to Bernoulli the diameter has directly influence on the speed of the air movement. This results from the resistance of the air by the inner surface mainly of the staple but also of the chanter itself.

You can easily test this by putting a wire of 0,6 mm with a once or twice winded knob into the staple and test at which point of the staple it has influence to which note in the upper octave.

Cheers and good look!

[Ted]

When I wrote the article 31 years ago, I was hoping for a mathematical answer to staple design. While it was an interesting exercise, it did not work well in practice. I moved on to a trial and error method that worked better. Some reed makers still use tubing they modify to try to fit a staple that works. I found by using a standard head shape, I could vary the staple blank dimensions to achieve proper tuning in most reeds. I used 0.548" wide narrow end for most concert pitch and 0.452" for flat chanters. I did find that some narrow chanters as well as many bass regulators required a 0.500" narrow end. I made a mandrel from a 9/64" rod to make the eye forming mandrel for these. The wide end was varied to tune the staple. I use a 0.020" thick copper blank, 2 1/16" to 2 1/8" long, with 0.548" and 0.620" ends, and a 1" taper to form the eye opening of 0.065" height for most Rowsome D chanters, for example.That only works for my head design and must be modified if you gouge a deeper tone chamber. Rolling your own gives fairly precise control over the tuning of the staple. You must use some modifications to a tubing staple or change the internal volume of the head to tune them. Works for me. YMMV A couple of thousandths variance does not seem to make much difference. I try to keep my blanks within a 0.003" tolerance.

[myrddinemrys]

I would be interested in reading that article myself; if you have a link for that, I would greatly appreciate it.

The chanter is a truncated cone, and the staple is basically an extension of that cone. The chanter, reed and all, ideally terminates when the reed lips are in a closed state. With an ideal cone, you can calculate the ideal length, and the taper along the full length of that cone, including the staple. With the instrument, we're not dealing with an ideal cone, meaning it does not have a perfectly straight taper, lips to bell. Given that, reasonable adjustments are made when making the reed, sometimes adjustments on the staple.

If you have a reed recipe with specific dimensions, and they work, stick with it. If you're experimenting with your own design, then make the best darned reed you can, then adjust, if necessary.

[Ted]

My article was based on the staple being an extension of the chanter's bore. That is not precisely how it works out. There are graphic plots of oboe bores including the reed. The oboe staple, although conical, has quite a different taper than the oboe bore. I left the mathematical theories behind and experimented. I made a variety of staples for a D chanter and tied the same head on each of them. I tried them in various D chanters and noted the results. I found I could extrapolate what would be the ideal staple, with my head design, for a chanter that would be in tune through both octaves. I used to keep five D test reeds, each with the same head design, but a different staple bore on my bench. The staples used the same length and eye size, but were variable as to their bottom ends. I would find which reed fit an unknown chanter best and adjust the staple, if needed to fit the unknown chanter. Most fit three of these designs. Narrow bore D chanters took an entirely different staple.

The article was in an early issue of the Irish Piper's Club newsletter from Seattle and is available to members.