Buffet English Horn Day 7 - 2/19/14

Two days ago I wrote about doing some work on the right hand Eb lever after its tube split during swedging. That lever fits between the two parts of the C# lever on an assembly, and it turns out my work with that assembly was not done. Today was focused on making a replacement for a stripped shaft lock screw on the lower C# lever. In this picture, the red circle indicates the hole where that screw should go.

The shaft lock screws hold the lower C# lever to the steel hinge rod that runs through this whole assembly. On the other end, the C# touchpiece is permanently attached to the rod with a spline. The Eb lever between them, however, floats freely on the rod and isn't attached to anything. That enables the player to press on the touchpiece and cause the lower C# lever to move, while the Eb lever can remain stationary. This is all necessitated by the fingering system for the english horn and the location on the instrument of the Eb key (which would be directly below the assembly in this picture) and the C# key (which would be immediately to the left of the lower C# lever). The reason the lower C# lever has screws holding it on (instead of being permanently attached like the C# touchpiece) is so that the lower C# lever and Eb lever can be removed for cleaning, oiling, or other servicing.

A similar mechanism exists on flutes to enable the instrument to play Bb and F#. However on most flutes the keys are secured to the rod with tapered pins that can be knocked out. Most oboe and english horn manufacturers use tiny screws instead. The upside to this is that they're a lot easier to remove without marring the key. The downside is that a tiny screw is a lot harder to replace than a tapered knock pin. That being said, here's the process I used:

The first thing was to clean up the threads on the inside of the hole with a tap. That's a watchmaker's tap going through the key. You can't see its threads in this picture because they're so small. Sorry about that.

With that being done, the first step in making the screw was to turn a piece of drill rod down to the correct diameter, in this case .045 inches, which is measured with a micrometer.

Once the rod was turned down the correct diameter, it was time to thread it. The plate in this picture has dies for making several different sizes of screws, and you can see the newly threaded rod coming through the fifth slot. This is a delicate step, because the rod is so narrow and fragile. As the die cuts metal away from the rod to make threads, it can snag and break the rod. That happened to me twice, and fortunately both times I was able to extract the broken part of the rod from the die plate.

Once the rod was fully threaded I cut off the excess and smoothed out the head of the screw, then cut a slot with a jeweler's saw. This was most easily done with the screw threaded into the correct sized hole on the die plate.

  
Here's what the finished screw looked like. I didn't make the penny. That's just to show how absurdly tiny the screw is.

After that, it was just a matter of installing the screw in the hole, which was a little harder than expected because I used a pretty cheap tap and die set and the hole didn't exactly match. But by threading the screw in nice and slow like, it all got trued up and now everything fits together quite nicely.

And that's how I made a shaft lock screw. It was terrifying!

Buffet English Horn Day 6 - 2/18/14

Today I was stuck at home waiting for a guy to come fix our washing machine. With all my tools at the shop, there wasn't much I could do, which is a shame, because I had a buttload of free time. However, between making oboe reeds and domestic stuff, I did find time to polish the keys. I'm really amazed at the condition of the plating. There are five or six keys with any noticeable plating loss, and on the others the plating looks really great.

Here's a pic of the keys, post-polishing!

Buffet English Horn Day 5 - 2/17/14

Today was a busy day between work and rehearsal, so I only had about a half hour between the two to work on the english horn. But 30 minutes is more than enough time to get caught in a quagmire. I'm pretty efficient at that.

I was doing the last of the swedging that I didn't complete yesterday on the Eb lever. It goes on the C# lever hinge rod, between the two ends of the C# lever. It's a key that gets used a lot, and has force exerted on it at kind of a weird angle, so it was severely worn and needed a lot of swedging. Like, more than I've ever needed to do on a key. You can see on this end how much of a gap there is between the tube and rod.

So I was doing working on that and things were going alright, but I failed to take one factor into account: As metal is worked, it hardens. So as I was swedging, repeatedly squishing and deforming the metal of the hinge tube, the metal was getting less and less flexible, until finally it couldn't absorb the stress being placed on it. That caused the end of the tube to crack in two places. This is something I should have foreseen, but thankfully all is not lost.

To fix my mistake, I first cleaned out the cracks with a fine jeweler's saw, then filled them both with silver solder. In this picture you can see that the left side of the hinge tube looks a little weird. That's the end that cracked, and the slightly darker color is the silver solder that pooled on the outside of the key.





In this next picture, you can see the end of the tube where it split. I didn't bother making the end of the tube look perfect, because that area is going to get cut off when the tube gets shortened in a few steps.

The next step was to file away the excess solder and sand the outside of the tube to restore a smooth finish and remove the distortion from the excess silver solder. It's difficult to see the color in this picture, but filing and sanding also removed the silver plating and exposed the base metal of the key - on this instrument the keys are made of brass. I'll need to buff and spot plate it later to fix that.

Next I needed to ream out the inside of the tube, which got a little bit of solder in it. That's not necessarily a bad thing, since now I can ream it just to the diameter I need so it will fit snugly on the hinge rod, thereby creating a new bearing surface in the tube out of silver solder.

Finally I shortened the tube a bit, since all that swedging made it a good bit longer, and it was no longer fitting between the two sections of the C# lever. This is when any of that nastiness at the end of the tube got removed.

Here's the whole assembly put back together. The Eb lever fits perfectly between the two halves of the C# lever, and fits snugly on the rod. Once it's spot plated, there should be no permanent damage.

Buffet English Horn Day 4 - 2/16/14

Today was devoted to swedging. There's not much to say about that. I did get to use the pliers I made yesterday, though they needed to be thinned out some more to fit some of the upper joint keys. More on that tomorrow. Mostly I try to use my swedging collets wherever possible, as I find them much more consistent and easier to control than the pliers.

The nice thing is that none of the keys were really mangled or completely blown-out, so the amount of swedging I had to do was pretty reasonable, and I'm very pleased with the results.

One consequence of swedging is that it makes the tubing longer. As you squish the tubing, the metal you're displacing needs someplace to go, like rolling out a log of Play-Doh. That means that later some of the tubes will have to be shortened to make them fit between their posts or between other keys. Done carefully, that allows a technician to shorten them just enough that they fit tightly, with no side to side movement at either end. That's how you get really well-fit keys, which move only in one direction - up and down.

Tomorrow is the last of the swedging, and a minor catastrophe.

Buffet English Horn Day 3 - 2/15/14

Today the first day for the body of the english horn to humidify in my super-advanced humidifier - a garbage bag with a wet sponge in it.

In the meantime, I made these swedging pliers today out of an old set of side-cutters that never really cut all that well. Swedging is the process of fitting a hinge tube to its corresponding rod by carefully squishing the tube to reduce its diameter. The idea is to make it so that the tube moves freely on the rod, but with no slop in the hinge. That way the keys can move smoothly up and down without having any wiggle back and forth. It also ensures the mechanism will be as quiet as possible. Over time, the repeated movement of the keys wears out the soft metal of their hinge tubes, reintroducing slop into the equation. However, keys that are swedged properly can go a long time before any slop is noticeable.

They'll be very helpful when I do key fitting tomorrow. I made them especially to get to the short hinge tubes on the upper and lower stack keys where it's difficult to get access.

Buffet English Horn Day 2 - 2/14/14

The universe's gift to me for Valentine's Day was a late opening at the shop due to snow, which meant I could still go in at my regular time (through some less-than-ideal driving conditions) and get some work done on the english horn. Today was a day just for cleaning. I cleaned both the upper and lower joints, then did some light polishing of the bore on the upper joint, which has some gouges in it. It looks like someone may have pushed a sharp implement up there, maybe in an attempt to remove a stuck swab. The damage isn't too severe, and after dressing and polishing it looks a lot better. The wood of the bore on the lower joint is pristine - I almost can't believe how nice it looks after cleaning.

Cleaning the keys was next. I simply ran them through an ultrasonic cleaner for a few minutes, rinsed, then immersed in silver dip to remove the built-up tarnish. This cleaning process is the reason I had to separate all the steel screws from the silver keys before cleaning, as the chemicals in the ultrasonic and the silver dip cause steel to rust very badly within a few hours of exposure. The keys came out great! 

Actually, in the right side of that picture you can see one steel rod that's pinned to its key (the C# touchpiece) and the little bit of rust that started to form after it was cleaned. Fortunately, that will come off.

Here's another shot of what they looked like pre-cleaning, as a comparison (though this one was taken without flash, d'oh!)

Buffet English Horn Day 1 - 2/13/14

As an oboist, I get occasional calls to play in musical pits, and the books often call for english horn. In the past when I've played those engagements I've always borrowed an english horn, but it's about time I have my own. So this post is about a personal project instead of a customer repair. It's a Buffet english horn that needs an overhaul and I intend to play in a show in exactly 3 weeks. Every day over the next 21 days, I'll be posting about the steps involved in this type of comprehensive repair, and chronicle its transition back to a fully functional instrument.

Aside from needing all new pads and corks, a lot of key fitting, and a good cleaning, the instrument appears to be in fair condition. The wood is free of cracks and has good tight grain, and the keywork hasn't sustained any serious damage. The plating is missing in the spots you'd expect, on touchpieces and the tops of keys, but even then it's probably over 95% intact. There is a lot of work to be done facing the tone holes to remove chips and defect from grain, but that's to be expected on an older instrument that's been sitting unused for a long time, as this one has.

There are a few problem spots. One post on the lower joint has had its face filed back, to the point that it will need to be replaced. The outer ring on the D key is split and slightly out of round, so the split will need to be filled and the key rerounded. Then there's this:

The Eb/B lever on the lower joint is bent, and it looks like the impact that bent it also knocked the lower post out of alignment. The threaded hole in the above picture is where that post was installed, and when the post moved it split the wood on the surface. The fortunate this is that the crack doesn't extend into the bore. Hopefully it will all fit back together nicely and make for an invisible repair. Here's another picture, this time with the post inserted. You can see that it's slanted slightly toward the left of the picture.

Day one involved taking a lot of notes, snapping a lot of pictures, and making some drawings for reference. Then it was on to disassembly. Everything came apart with very little resistance. I removed all the keys and springs, then removed all the regulation and adjustment screws from the keys. The silver plated keys and the steel screws can't be subjected to the same cleaning chemicals, so it's necessary to remove every single screw. By the same token, the steel springs on the body shouldn't be subjected to too much moisture, and since I'll be cleaning the body it was necessary to remove them. Plus it's easier to work on the body when it's not covered in tiny little needle springs.

Here are the keys after disassembly, and with the pads removed. They're pretty tarnished, but should clean up nicely. Aside from a few bent parts and one stripped shaft lock screw (for which I think I can make a replacement), things look good.

And here's the body after disassembly. Oof. I need to play this thing in three weeks.

Here goes!