Oboe Bell Rebuild

This Jardé oboe came in for an overhaul, and already needed a bunch of extra work beyond a “normal” overhaul. New screws for both the right and left hand key stacks, a replacement post ball for the trill touchpieces, a sleeve on the middle tenon to prevent it from wobbling, plenty of new springs, and a new pad cup for the Low C key. But the most daunting job was repairing this badly damaged bell. The reinforcing ring at the bottom was gone, it had four large cracks extending halfway up from the bottom and at some point someone did some kind of the work on it, the goal of which I can’t determine. But they removed material from the bottom of the bell opening - unevenly, so it sat crooked and had a wide flat spot all the way around - and aggressively sanded material away from the bottom of the opening. In the “before” pictures, you can see sanding lines extending halfway up the inside of the bell. 

The solution I came up with was to remove some more material until I had a nice even surface to work with, then make an insert that could be installed to replace the missing wood. The process started with facing off the end of the bell on the lathe to make a smooth, flat surface. Then material was carefully removed from the inside of the bell by boring it out, until the most heavily sanded areas had been removed. Next, a roughly shaped insert was cut out of a large piece of grenadilla - in this case, a blank used for making a clarinet bell was the handiest piece I had. The insert was made so its exterior surface would precisely fit the area that had been bored out of the bell, but it was left longer than needed, and with a narrower opening, so that those dimensions could be shaped to the contour of the bell after it was installed. The insert was glued in with epoxy and allowed to set, then the work of shaping began in earnest. Without another bell from the same manufacturer to use as a reference (not that it might have been any help - Jarde oboes can be somewhat inconsistent) I had to rely on the existing shapes and lines of the bell to contour the insert. By extending the lines that were already there, I was able to remove the excess material so that the insert is largely undetectable except when viewed from a couple inches away. Of course, the shape of the bell also influences tone and intonation, especially for the lowest notes, and I’m happy to report that the restored bell plays with an even tone and relatively good intonation, far better than it did when it came in.

After everything was properly shaped, I still had to fill the cracks and clean them up, then do something about the missing bell ring. Without a ring press or the ability to fabricate a new metal ring, I elected to enlarge the groove and install a carbon fiber band. The band will provide at least as much reinforcing strength as a metal band would, and it gives a nice two-tone effect, like a faux inlay.

This was an intimidating job, and because of the time I invested it wasn’t a hugely profitable venture, but it was a learning experience, and when you work on vintage oboes with a certain regularity, the ability to mend a damaged and obsolete bell is a skill that may be required from time to time.

These first few "before" pics show, first,  that the bell listed to the right instead of standing up straight, because of the material that had been unevenly removed from the bottom. Second, one of the long cracks from the exterior. And third, the interior of the bell, showing the cracks from the inside, the wide flat spot around the opening where material was removed, and sanding marks extending up into the throat of the bell.

The cracks have been filled but not yet dressed or finished, and the bell is placed on an arbor in the lathe to allow the bottom of the bell opening - where the damage is worst - to be cut out.

After removing the most damaged section of wood. You can also see some of the sanding marks further up the bell from where it was aggressively sanded by the last person that worked on it. Those will later be cleaned up and made smooth.

This picture and the previous two show the insert being cut out of a clarinet bell blank - a large, rough cut piece of grenadilla that could be turned down into a clarinet bell. The insert is tapered to match the cut that was made on the inside of the bell, and is left longer and wider than it needs to be at the bottom, so it can be shaped later.

The insert was glued in, and a jig applied consistent pressure while it set.

The inside of the bell with the insert glued in, before any shaping. Lots of adhesive to be cleaned up!

After the insert was shaped to match the contours of the bell, it was sanded by hand on the lathe with progressively finer abrasive (second photo) to give a smooth finish. Then a carbon fiber band was installed in the groove for the old bell ring, both for reinforcement and aesthetics.

The interior after finishing. This isn't the best picture, but there are no more sanding marks, and the cracks no longer stand out from the inside. If you look closely at the left and right sides, you can see where the insert ends as the grain shifts slightly.

A close up of the exterior, showing that the insert is effectively invisible.