Those of you who make reeds from tube cane or anyone who is curious about how this is done should read this.
These are photos of a tool sold known as a cane splitter. They come in different shapes and sizes. Costing between $60-$150, I find these tools to be a complete waste of money and even detrimental to finding the best section of a piece of cane to use.
The most important attributes to look for in a piece of cane are symmetry and straightness. However, no tube is perfectly round or perfectly cylindrical. Nature has curved and warped the cane. It's up to the reed maker to select pieces or sections of the tube that are as straight and uniformly curved as possible.
The cane splitter simply cuts the tube into three or four sections. By using it it is not possible to select the section of the tube that yields a symmetrical curve.
Let's back up for a minute, though.
Selecting the tube diameter:
First it's best to find the diameter of the tube by using a circle drafting template ($5). You can find these in craft stores or office supply stores.
A radius gauge sold by double reed suppliers can work, but only measures one section of the tube. The curve of the cane may increase or flatten out in the other parts.
The tube should fit in either the 24mm or 25mm circles. The tube should not vary more than 1mm from end to end nor have a bulge in the middle. Cane from these tubes will yield the best tip openings.
Now you can split the cane. Splitting the cane dry will make the job easier although it doesn't matter if it's already soaked.
Cane split incorrectly:
A four-way split is preferable to a three-way because it can yield a more or less symmetrically curved piece of cane.
However, the tube illustrated above is split in such a way as to yield pieces that have a "hockey stick", asymmetrical curve.
It's all about tip openings, folks! A symmetrical curve to the tube section will tend to yield a more symmetrical tip opening on the finished reed because of the "muscle memory" in the cane.
Here is a method for finding the right orientation for your splits. I learned this from Mike Sweeney and I think it was first developed by Arlen Fast, so thanks to these bassoonists.
Using a caliper ($15.00), find the point on the tube where the diameter is smallest (or largest diameter if you prefer). Mark this point on the tube with a marker.
Fit the tube into the proper circle on the template again. Line the marked spot up with one of the four compass points marked on the rim of the circle and rotate 45 degrees. Mark the four compass points. This is where you will split the cane.
If there is a knot or a node where a branch sprouted on the cane, don't use that section. If the tube has a noticeable change in diameter at one end I'll throw away that part when cutting the split pieces down to size prior to gouging.