Thursday, July 15, 2010

What The Heck Is Swedge?

Woodwinds that are old, or those that have had a lot of use, tend to show their age in the hinge rod tubes. Over time, the metal of the tube wears down and the key develops side motion. With enough wear, the tube may also develop an out-of-roundness, causing the key to become unstable, resulting in a leak. Replacing a pad on an instrument that has this kind of wear will not stop the leak. What to do? Swedging is the remedy.

Using a special tool, the hinge tube is compressed around the rod with a twisting motion. This causes the key to fit more snuggly around the rod and also causes the metal of the tube to be stretched, thereby taking up the space between the keys, or the key and the post.

This kind of repair requires the expertise of a skilled repair technician, since damage can occur to both the key and the rod if done improperly. Rarely is it possible to swedge a key while it is still on the instrument. So, the procedure requires the key to be individually removed and replaced after each bit of compression, to check for binding, or to see if the key requires more compression. Just swedging the lower stack on a saxophone may require disassembly and re-assembly of those keys a dozen times or more. Yes, it can be time consuming, and no, a computer will never be able to do it.

So, before you plunk down your money for a yard sale horn, grab onto the key hinge rod tube, and see if it moves up and down the rod. If, it does, know that the price to make that horn play will include whatever your local musical instrument repair person charges to swedge the entire horn. Because, usually, if some of the keys have play, they all do. But, at least now you know what swedging is.