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Screw Bell Conversion

1. Why a Screw Bell?

Screw bell horns offer several advantages over fixed bell models. The most obvious is portability. The horn can be transported in a compact, easy to carry package that fits easily in a crowded bus or subway or in an airplane overhead compartment. Taking the bell off the horn also reduces damage caused by hard knocks or falls since the thin bell no longer has to bear the weight of the valve machine. The ring itself reinforces the bell at its weakest point.

Attaching the male ring-click for larger imageA less obvious advantage is the ability to add different bell flares to the instrument. An old instrument can be rejuvenated with a new flare. Flares of different alloys, sizes, weights, or hardness, or with features such as garlands can be added as well. (See our Schmid bell section.) Since the flare has about 75% of the radiating surface of the instrument a change here can have a profound effect on the sound and feel of a horn.

2. What Kind of Ring?

We recommend Alexander, Engelbert Schmid and Finke screw rings. Cutting the bell-click for larger imageAlexander rings are often used in screw-bell conversions. They are strong and durable and are used when compatibility with Alexander, Lawson, Conn/King,  Holton, and Atkinson horns is desired. Many small makers (Lewis, Rauch, etc.) use Alexander compatible rings. Alexander rings fit small bell horns without modification. To fit larger bells they must be adjusted to fit the larger taper. Unless the inner diameter is changed to a standard size using replacement bells will result in a "step" where the bells join. Unless otherwise instructed, we fit Alexander rings on large bells to the Lawson dimension at that point to insure compatibility with Lawson flares. (The most common Alex-thread replacement flare.)

Please be aware that several makers use rings that are "Alexander compatible". These copies may or may not fit other instruments with similar "compatible" rings. We use genuine manufacturer's parts only.

Attaching the female ring-click for larger imageWe recommend Engelbert Schmid bell rings. They are slightly lighter than Alex rings and allow compatibility with a wide range of Schmid bell flares. The unique design of the Schmid bell tapers makes it possible to use medium, wide, and extra-wide flares on the same instrument with no step at the ring. Schmid bells are readily available in the full range of sizes and alloys.

As Finke horns have increased in number and popularity we have decided to offer Finke rings. Along with Engelbert Schmid, Finke designs their bell flares so that they have a common inner diameter at the screw ring. That means that owners of horns with Finke rings may use both medium (Brendan) and wide (Americus) with no step at the joint or intonation penalty. Finke is the only maker other than Schmid who offers (and stocks) after-market bell flares. See our Finke Bell Flares section for ordering information.

In addition to the rings listed above, we can obtain rings from Paxman, Yamaha, or any other currently active maker. The bell rings we use are genuine manufacturer's parts. They are not copies. Of course, we can custom make bell rings in any dimension. (We've made screw rings for everything from piccolo trumpets to tubas!) Custom rings are often used to replaced damaged or worn out rings on Geyers, C.F. Schmidts, and other classic instruments.

3. The Process

Finishing the male ring-click for larger imageThe first step in converting a horn to screw bell is the removal of the bell from the instrument. Any major dents are removed and the bell rim and throat are rounded up to accept the bell ring. Next, the lower (male) half of the ring is slid over the bell and soldered in place. Then the bell is cut and the flare is cleaned up.

The upper (female) half of the ring is then attached to the tail of the bell and finished. The last step is reinstallation of the tail to the horn and the trimming and refitting of the main bell brace. The tail and flare are polished and (if desired) relacquered.

Finishing the female ring-click for larger imageThere are other, less expensive ways to install a bell ring but the distortion of the bell entailed results in significant work-hardening of the metal with a strong chance of changing the sound. The cosmetic results are also often less than satisfactory.

 

 

4. Options

Lacquer

We normally relacquer all our repair work. We use a baked on epoxy lacquer finish unless otherwise requested.  We will relacquer the entire bell tail and flare to minimize the "patched" look.  Because of advances in lacquer removal technique, we no longer make an extra charge for UMI manufactured instruments.

Cases

We have a full range of screw bell horn cases and gig bags available from Pro-Tec, Osmun, and Bags Cases.

 

5. Time and Cost

We normally need to have the horn in the shop for two to four days. Please make an appointment at least a week in advance by email or by calling us at 781 646 5756. We can usually turn a horn around in one (long) day if necessary.

A screw bell conversion costs $675 ($600 for Unlacquered horns). All our work is guaranteed. The cosmetic quality of your screw bell conversion will be equal to or greater than that of a factory screw bell installation. Naturally, custom made rings are priced individually, according to the complexity of the job.

How to ship your horn to us

John holding the finished YHR667V with Schmid screw ring

Osmun Music, Inc.

PHONE: 1 (781) 646-5756

FAX: 1 (781) 646-2480

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