Although I had already faced the upper joint tone holes, I decided to go back and check everything again with a discriminating eye. And it's a good thing I did, because a lot of them still had chips or uneven rims, and needed more attention. The order of operations I ended up using that gave me the results you see below is this:
1) Dip the head of a pin in medium-thin superglue, then run a bead around the rim of the tone hole. Allow it to set a few minutes
2) Dress the tone hole's outside taper with my fancy new facers covered with 220 grit sandpaper
3) Establish a flat surface on the top of the tone hole with the flat side of the facer and 600 grit sandpaper (the 600 grit loads up quickly so it has to be replaced frequently)
4) Once a smooth, flat surface is established (ideally not too wide), chamfer the inside of the tone hole with a pad seat reamer (pictured, available from Ferree's Tools)5) Check everything under magnification. Sometimes the pad seat reamer catches on the tone hole rim and chips it. Simply fill any chips with glue and repeat above steps.
6) Continue checking obsessively until your eyes hurt
The result is a smooth, even, defect-free rim like you see below.
With the tone holes faced, I took a detour to a small project on the upper joint - wrapping the upper tenon rail in silk. Wooden tenons - especially middle joint tenons - tend to be come wobbly over time. A lot of players seem to think that this can be remedied by replacing the tenon cork, but the tenon cork really only does two things. It provides friction to prevent the joints from falling apart (longitudinal movement), and it acts as a gasket to create an airtight seal between the joints. A tenon cork can't, however, eliminate wobble (lateral movement). The middle tenon on a woodwind instrument is usually very short compared to the length of the upper and lower joints, so those joints exert a huge amount of leverage on that little tenon. Cork is just too soft to be able to withstand those stresses. The rails, however, are strong enough to hold up against that lateral force and prevent wobbling. Rails can either be wood (or plastic, if that's what the instrument is made of) or they can be shrouded with a metal sleeve, in which case the socket will have a matching metal liner.
Metal rails have a two-fold advantage. First, they don't expand or contract with changes in humidity and temperature, so if an instrument has metal rails and a metal-lined socket the tolerances between them can be very close to ensure a snug fit. Wood rails and sockets swell and contract a lot more, so they can't be fit as closely lest they become stuck. The second benefit of metal rails is that they don't wear as much as wood. Even a wood as tough as grenadilla will eventually wear down under the lateral stresses exerted on the middle tenon. That's why older clarinets and oboes almost always have a wobbly middle tenon, and why this english horn did, too.
Whoever engineered this instrument clearly understood this, because it has a metal liner in the middle socket and the lower rail of the middle tenon has a metal sleeve. Unfortunately, the upper rail takes the brunt of those lateral forces, so it had worn down and there was a noticeable wobble. There are several ways to deal with this problem. Some techs wrap the rails in cork, but I don't like that because it doesn't seem to last. The ideal fix is to machine a new rail out of plastic, but for that you need a beefier lathe than I have, because you also have to cut the lower rail off the tenon in order to slip the upper rail on. I therefore went with the third option, which is to wrap the rail in silk. Silk is the preffered material for this process because it doesn't stretch like cotton (which ensures you get an even layer all the way around the rail). It also doesn't compress, so it can hold up against that lateral movement. Incidentally, the fact that silk doesn't compress is the reason a stuck silk swab can't be extracted by pulling harder on it.
The process of installing the silk wrap is actually pretty simple. You cut a strip of silk, making sure to follow the weft of the fabric. Then you tack it to the rail with a dab of super glue, and slowly wrap it around while following with thin super glue. The whole strip should be saturated with glue when you're done. This keeps it in place on the tenon and adds a little bit of reinforcement. Once it's dry, you can go around with a razor blade and cut off any excess. The silk will be stiff enough to cut cleanly.
After it's in place, you can file or sand the wrap until it fits snugly in the socket. This one required minimal fitting, and now it fits perfectly in the socket with no wobble.
After that, I put the springs back on the upper joint, made final adjustments to key fitting, and started fitting and installing pads on the upper joint keys. More on that with tomorrow's post, which will focus on the same process but for the lower joint (this post is just getting a little long). But here are all the upper joint pads glued into their cups
And then on the 17th day, I padded. Here are the first two keys, the G and Bb, on the instrument at the start of that process. I anticipate there are between 10 and 15 hours of padding, regulation, key fitting, and other adjustments between me and a functional english horn.
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