Laubin English Horn Hinge Tube Insert

This is the C key from the upper joint of a Laubin english horn, in for an overhaul. Since tight key fit is essential to stable padding when working with cork pads, I spend a lot of time in my overhauls fitting keys to remove any "slop" in the mechanism. A lot of times that involves sweding the tube on the key to shrink it a little bit, and make it fit more snugly on the hinge screw. However, this is one of several keys on an oboe that can't be swedged, because of the long arm that's attached along its length. There's not a good way to get a tool in there to shrink the tube if you don't have access to the entire circumference of the tube. If you look at the end of the tube on this key, you can see that it's been "wallered out" somehow, so the diameter is way too large on that end. That allows the key to wobble on the hinge. The normal way of dealing with this would be to make an oversized (greater diameter) hinge screw and ream the inside of the tube to fit it, thereby enlarging the tube enough to cut out the "wallered" section. However, I'd already made an oversized hinge screw for the entire left hand section on this instrument. There were other keys in that stack had also been loose, and they all fit beautifully after reaming and lapping to the new screw. However, this one was still loose. Not wanting to make an even larger screw and ream all the other keys again, I decided to make an insert for this tube that would allow it to fit snugly. 

The rough surface on the inside of the tube is where it was still loose on the oversized screw. The reamer that I ran through didn't even touch that area because it's so blown-out.

This thick-walled brass tube has a very small center hole, much smaller than the diameter of the hinge screw. After the insert is installed, that hole will help guide the reamers through as I gradually enlarge it to the correct size. It's being turned down to a diameter that will fit in the tube on the key.

Here's that same piece after being cut off and cleaned up in the bench motor.

The piece was "tinned" to make it easier to solder in place. The whole part was heated and solder flowed over the surface, then the solder was wiped off while still liquid, leaving a thin layer on the surface. When soldered in to the key, solder will flow much more easily over this surface than it would the raw brass underneath.

After soldering the insert. The end of it sticks out beyond the end of the key tube, and will be trimmed off later. The finished insert was intentionally made larger (greater diameter) than the hole in the key, and the key was reamed up to match it. That created a nice clean surface inside the key for soldering, and the inner diamter of the key tube was made uniform to match the outer diameter of the insert.

Reaming the insert up to size. Progressively larger reamers are used, each one removing a few thousandths of an inch of material.

The last reamer sticking out, having passed all the way through the insert. The chips of material it removed are visible on the end.

The interior surface of the insert is much smoother and more uniform than the original key tube.

After a little bit of lapping to remove to make the fit smooth, the hinge screw fits nice and snug in the key now, with no wobbling on either end.

Loree Oboe Overhaul Time-Lapse Video

I've been wanting to do a time-lapse of a major repair for some time, so when this oboe came across my bench it seemed like the perfect opportunity. This is an AZ series Loree oboe from the late 1950's that hadn't been serviced in some time, so it needed a lot of attention. 6 minutes is probably a bit too long for a time-lapse, but the job took 20+ hours so I cut out as much as I could. That means a lot of little steps have been left out and some of the tasks that are shown will appear simplified. This video doesn't begin to show the amount of fussing and fiddling that goes in to every part of a comprehensive repair, but does give an idea. Most of the steps are directed toward ensuring that the pads are dead level to the tone holes and that they will close exactly the same way, in exactly the same position, with exactly the same relationship to other keys, every time for hundreds of thousands of repetitions.

That baking soda bath to remove tarnish was somewhat effective, but this was my first time trying it and I'll need to tinker with the process to see if can be improved. There was still a lot of polishing to be done after that.

The musical accompaniments are Perpetuum Mobile and Trish-Trasch Polka, both by Johann Strauss II.

Oboe Octave Touchpiece Extension

This Loree oboe belongs to a local university, and is in use by a student who has difficulty reaching the thumb touchpiece for the octave key. Her professor asked if an extension could be made to improve the ergonomics, based on one she'd had made by another technician for another oboe. Making an extension plate is simple enough - it's just a piece of nickel sheet with the edges rounded over to remove any sharp burrs, and curved a little bit to match the contour of the body and fit in the case. In most cases, it's then soldered or brazed on to the original touchpiece. However, with this being a school-owned instrument, the extension will need to be removed at some point so that another student can use it. Removing a soldered or brazed part would require bringing it back to the shop and would leave residue that would require some amount of cleanup. So it made more sense to manufacture an extension that could be affixed mechanically, in this case by screws.

The extension needed to add at least 3/16" to the left side of the touchpiece, and I chose to make it a little longer than that just to be safe.

The process of making the extension isn't very interesting. A template was marked out on a sheet of nickel, cut out, and the edges sanded to achieve the right shape and contour. Then it was formed into a curved shape to somewhat match the curve of the instrument body. Holes were drilled in the plate where it would meet the underside of the touchpiece, then matching holes were drilled and tapped in the touchpiece. A couple of 2.0x0.4 metric screws were modified to fit, and the part was ready to install, which was as simple as screwing it on. That's it! The next few pictures just show the completed part.

The extension in place. It's thinner in the area that sits under the touchpiece, to allow for adequate travel of the key.

A view from under the key. The extension can be removed by anyone simply by unscrewing it.

With a cork on the extension, the screws are hidden. The cork contacts the body when the touchpiece is depressed to control key travel. When the extension is removed, a piece of cork affixed directly to the bottom of the touchpiece will serve the same function and cover up the screw holes, so there will be no visible evidence that the extension was ever installed.

The touchpiece with extension mounted on the instrument. 

Resetting a Buffet Clarinet Post

This Buffet clarinet came to me twice in the same year because the hinge screw on the Side F# key had snapped off at the threads. The first time I simply manufactured and installed a new screw, but I did notice at the time that it felt a little tight going in. This time I investigated further and discovered that the underlying problem was a misalignment between the holes in the threaded post and the unthreaded post, which hold the screw. The hole in the unthreaded post was angled too far downward, so that when the screw was fully inserted, that post pushed down on it while the threaded post pulled up on it. The screw broke at the end of the threads because that's where the diameter is thinnest and weakest. The fix would be to change the angle of that hole.

The way I saw it, there were three potential ways to address the issue:

1) Raise the unthreaded post so that the angle of the hole was in line with the threaded post. 

2) Drill out the hole in the unthreaded post, then solder in a bushing at the correct angle, using the screw as a guide. 

3) Completely fill in the unthreaded post with a soldered plug, then re-drill it at the correct angle using a post-drilling jig.

At the time, I didn't have a post-drilling jig (I do now!) so option 3 was out, but I did have a drilling jig for the body, as detailed in a previous post, so I chose option 1 to give that tool a workout, though option 2 would have been just as good.

The first step was to remove the post and drill out the post-hole in the body to remove the threads. Because the post's height and radial alignment are both dictated by how far it's threaded in to the post-hole, and because both of those variables have to line up at exactly the same point, new threads would have to be cut into a bushing, then aligned on the body.

The small hole at the center of the picture was the post-hole. This is after it was drilled out.

Below is the bushing installed on the post. It's just a piece of ABS plastic, turned on the lathe and threaded.

The post was threaded into the bushing before installation.

The bushing and unthreaded post were glued in to the post-hole in the body together, using the screw to properly align things with the threaded post. Once the glue set, the pad had to be replaced to account for the slightly different angle at which the key now meets its tone hole, and the problem of the broken screws should now be permanently resolved.

The repositioned post is at the center of the photo. Looking at the base, you can see that it's now raised slightly off of the body. It's not cosmetically perfect, but probably not the kind of thing you'd notice unless you were looking for it.

Holton Alto Horn Leadpipe

This Holton alto horn, circa 1913, came in to the shop with a leadpipe that was not only damaged, but mostly sheared off. That necessitated replacing the leadpipe and mouthpiece receiver, but the age and obscurity of this instrument meant that no replacement parts are available. The only option, then, was to custom bend a new leadpipe. 

The remnant that was still on the instrument appeared to have been a replacement, so I was already two degrees removed from being able to replicate the original. Because mouthpiece shanks weren't yet standardized in the first few decades of the 20th century, it's almost impossible to know what sort of mouthpiece and receiver this instrument was designed for, without seeing an original. Further, without those pieces of information, it's even more difficult to determine what the original leadpipe dimensions would have been.

However, we work in the real world, and one has to learn to work with situations where incomplete information is all that's available. What we did know were the dimensions of a modern alto horn mouthpiece (not quite the same as a trumpet, or a mellophone), and of a modern mouthpiece receiver. Having secured one of those, it was possible to figure out what dimensions would be needed for the leadpipe. In an ideal setting, we could have gotten a piece of tubing drawn to a custom taper to fit those dimensions, but within the owner's non-infinite budget the best option was to use a section of a universal cornet leadpipe that matched pretty closely. They wanted an instrument that would work reasonably well, and not a museum piece, so I had no qualms about making that compromise in the interest of efficiency. 

There are no pictures of the process, but below you can see the before and after. The new pipe came straight and was filled with pitch, so fitting it required bending by hand over wooden forms to acheive the necessary curves. The pitch prevents the tube from kinking, though it doesn't prevent any distortion around the bends, so after draining the pitch and cleaning the tube, it had to be rounded out by pushing through graduated dent balls. For that part of the process I always solder several braces across the tube to preserve the angle of the bends while working. After rough-buffing, the part was soldered on, then it got a color buff and a coat of lacquer. Why lacquer a brass part on a heavily tarnished silver instrument? I don't have a good answer for that, except that I thought it looked better than leaving the part raw and I took some pride in the final product. 

The instrument as it arrived, with the remnant of the old mouthpipe still in place. 

The new part installed, buffed, and lacquered.

Another view of the final result.

Tone Hole Bushings

About once a year, a co-worker brings me her Eb clarinet and asks to have it looked at before she uses it in a performance. I've worked on it several times, but it's always a last-minute thing so I can only devote enough time to get it to limp along for a few weeks. Then it goes back into storage until the next emergency. This time was no different, except that things had deteriorated to the point that I couldn't let it go any more without doing some major work. The top of the body has a few cracks in it that had been previously repaired by someone else with little success. In addition, because the cracks ran through the top two trill tone holes, they'd attempted to seal and rebuild the tone hole rims with superglue. The result was pretty gnarly looking, and was still leaking. I thought this would be a perfect opportunity to give my new drilling jig a workout by replacing those two tone holes. I did a lot of other work, too, filling the cracks and banding the top of the joint with carbon fiber to repair it in a more permanent fashion than the previous technician. Those tone hole bushings, though...

Because she needed the instrument back in a hurry, I didn't have time to order a tool for cutting out the old tone holes. So I made this one by turning, drilling, and tapping a piece of steel. Then I filed and sharpened the twin cutting edges by hand. The two brass pilots thread into the cutter to keep it centered in the tone hole while cutting. The tone holes are different diameters, thus the need for two pilots.

You can see the previous work on the tone hole in the center of the photo and the one to its right. The rim is just superglue that's been layered on and then filed to something resembling flat. The rims are very wide, making it difficult to get a pad to seal. Not that it would have mattered, because the tone holes still leaked through the cracks. The tone hole in the center is about to be cut out on the drill press in this picture.

I turned these inserts on the lathe out of ABS. They'll be the new tone holes.

After drilling out the old damage, here's what's left. The inserts will drop right into those holes, with some fitting and adjusting.

The inserts are installed with epoxy, then dressed to make sure they sit flush. It's not a terrible result for my first time at this.

In order for the pitch and timbre to be correct, the inserts will need to be reamed with a tapered reamer. The straight holes I made in these are a little undersized to allow for that. I wasn't able to ream these before returning instrument so things are a little wonky, but it's a vast improvement over the leaky mess it was before, and I can complete the job by reaming them after my coworker is done with her gig.

Drilling Jig

Larry Mueller, who is an outstanding oboe technician and an equally skilled tool maker/designer, let me try out this prototype work fixture for holding clarinet, oboe, and english horn joints for drilling. He does a lot of tone hole replacement, a skillset I've yet to develop, and this tool is ideal for doing that sort of work when one doesn't have access to a mill with an indexing head (which I don't). But we've both worked separately on installing Left F mechanisms on oboes, and the jig is also well-suited to drilling holes for new posts, so I got to check it out with that purpose in mind. Unsurprisingly, it's well thought-out and well made, and easy to use. I tested it out on a junker clarinet body and was pleased with the results.

I don't have a mill (yet) but I do have a decent drill press, and the jig is useful even with this simple set up. A compound slide table allows the joint to be lined up perfectly under the chuck, and the jig itself allows you to rotate the instrument without losing your X and Y axis alignment. It's also rigid enough to hold that alignment during and after drilling.

Drilling test holes with a homemade cutter, based on a design that was also shared by Larry. The cutter makes a hole for the post threads and puts a relief at the top to fit the flange (base) of the post. The cutter is visible at the top of the photo, and in most of the other pics.

The jig also allows cuts to be easily repeated. I wanted the relief at the top of this hole to be a little deeper, and was able to line it up in exactly the same position under cutter to do that, after having rotated it out of position to check the finish on the holes.

I threaded these posts into the holes without tapping them first, to see how it would go. The left one is almost straight, the right one isn't close. The radial alignment is off on both of them, because these posts were pre-drilled. A functional post can only be drilled after it's installed to insure the alignment will be correct. We're just messing around here, though, and I had these pre-drilled posts laying around.

This hole did get threaded, with a spare post that I turned into a rudimentary tap.

See? Just cut some notches into the threads and you've got a simple wood tap that will work in a pinch.

It was much easier to get the post straight in the threaded hole. This one came out beautifully.

This is the kind of tool that could vastly expand the work you can do.