Bell design

[BflatBass]

I have a couple of totally noob questions here.
What is the difference between a one piece and two piece bell?

Also, I've noticed that the bell wire is a separate piece added to the bell flare. Is the bell wire soldered all the way around when added and if a trombone is made with an 'unsoldered' bell does that mean it also has no wire?

Thanks,
Robert

[paulyg]

A one-piece bell is one piece of sheet brass that is brazed longitudinally, and spun-form. A two-piece bell is generally where the bell flare and the bell throat are each brazed from a single piece of sheet brass and joined with a circumferential braze.

Most bells have a rim wire, be they soldered or unsoldered. An exception to this is the conn vocabell model. A soldered rim wire means that molten solder is introduced to bond the rim wire to the bell bead (the folded brass enclosing the rim wire). When manufacturing an unsoldered bell, this step is skipped.

To tell if a bell is a one-piece or two-piece bell, look for the braze where the flare begins. On some two-piece bells, this seam is nearly invisible, but it is there. To see if a bell is soldered or not, inspect the rim of the bell. If there is gray material (the solder) around the rim, the bell is soldered. If this is not visible, chances are that the bell is not soldered.

An additional variation is called the french bead. I myself am a little confused as to whether this simply involves adding more solder to the bell rim and hammering the rim flat, or if a flat rim wire is used in addition.

Examples of the two approaches would be the Conn 8/88H and the Bach 42. The conns have two-piece, unsoldered bells. The bachs have one-piece, soldered bells. The differences between the two models go beyond just the bell construction, but the differences in how the bells of those instruments are designed goes a long way in determining the differences playing and sound characteristics between those instruments.

[rptbone]

Is there much difference between the two bell construction methods regarding manufacturing labor hours? Which one is “easier” to make or takes less time?

[harrisonreed]

NB: Conn stopped doing unsoldered bells quite a long time ago. Still two piece though.

The 88H is now a thicker two piece bell, soldered rim.

[Kbiggs]

One or two other things (of a million or more) about bell design:

For American horns, there are three basic profiles or tapers, which I call Bach, Conn, and King.

Bach: taper starts earlier, creating a larger throat and spout, and a more gradual curve leading to the bell edge.
Conn: taper starts later, narrower throat and spout, and a more abrupt curve leading to the bell edge.
King: more pronounced than the Conn.

Other nations with a strong history of brass manufacturing include Britain, France, Germany, the Czech Republic and nearby countries. They have their own “national styles” of design and rims.

When you combine taper and bead rim with one vs. two piece construction, gauge, material, and manufacturing process, along with any secret sauce of the individual makers, you have an infinite number of possibilities.

Bear in mind that the bell designs we currently see are the result of historical experimentation. Some designs are tried and true—when played by similar players, they will tend to sound similar, and they will produce a type of sound that is desired at that time and place. Hence the tendency of many trombone sections to use instruments of similar make or even the same brand—but there are many exceptions to the rule (so to speak).

As to how those different designs influence a player’s sound, you’ll find some descriptions on manufacturer’s websites, esp. Edwards and Shires, which make a wide variety of different bells.

[elmsandr]

Is there much difference between the two bell construction methods regarding manufacturing labor hours? Which one is “easier” to make or takes less time?

The answer is, like everything else, “it depends”. You could make a 2 piece with a near net stamping for the flare popped out of an automatic press at 55 strokes per minute… but I don’t think anybody is doing that. Maybe on average the one piece takes more time as they are making a more severe change to the material to get it to net shape, but I haven’t tried to figure that.

I’ll bet the current Conn Selmer plant in Elkhart knows this exactly. I’d also bet they would never tell. That said, their student and intermediate horns are often 2 piece instead of 1 piece….

Cheers,
Andy

[rptbone]

Thank Andy. That’s an interesting observation.

[Burgerbob]

It was my understanding that one piece bells have a higher rate of failure when being made.

[Dennis]

A one-piece bell is one piece of sheet brass that is brazed longitudinally, and spun-form. A two-piece bell is generally where the bell flare and the bell throat are each brazed from a single piece of sheet brass and joined with a circumferential braze.
---Snip---
An additional variation is called the french bead. I myself am a little confused as to whether this simply involves adding more solder to the bell rim and hammering the rim flat, or if a flat rim wire is used in addition.

There are two approaches to the flare of a two-piece bell. The older method involves forming a larger, truncated cone and hammering/spinning it into shape. More recently, the flare is spun from a single sheet of circular brass. Bells formed by the old method display an X-seam.

The stem of a two-piece bell is formed in the same way as a one-piece bell is formed. Two piece bells give the designer more flexibility in manipulating the final bell gauge in that difference sheet gauges can be chosen for the stem and flare.

I believe that a French bead is formed with a flat bead wire. The only French bead rims I've seen were soldered, but I'm not sure if that's part of the requirement for French beads.

[Dennis]

It was my understanding that one piece bells have a higher rate of failure when being made.

One of the big differences between one-piece and two-piece bells is that one-piece bells are much thinner at the rim than they are at the stem. I'm sure that it's much easier to ruin a one-piece bell when spinning the flare.

[BassBoneBrian20]

One piece bell is essentially one piece of metal formed the bell with one long seam that runs parallel to your hand slide.

Two piece is 2 separate pieces of metal that form the bell, with the bell being separate from the bell stem section.

[Doug Elliott]

I have a Conn from the very early 1900's that has a triangular insert in the flare, so the seam is an upside down Y.

[Blabberbucket]

An additional variation is called the french bead. I myself am a little confused as to whether this simply involves adding more solder to the bell rim and hammering the rim flat, or if a flat rim wire is used in addition.

A French Bead traditionally uses a half-round wire instead of a full-round wire that you would see on most modern bells. French Beads can be either soldered or unsoldered as far as I am aware.

Is there much difference between the two bell construction methods regarding manufacturing labor hours? Which one is “easier” to make or takes less time?

Two piece bells are easier to manufacture as the stem can be drawn separately from the flare, and the flare can be spun separately from the stem before they are brazed together for final spin and beading. This requires less working than a one-piece bell and less skill in the spinning stages.

One piece bell is essentially one piece of metal formed the bell with one long seam that runs parallel to your hand slide.

The seam does not necessarily have to be parallel to the handslide, though instruments are typically built in that manner.

I have a Conn from the very early 1900's that has a triangular insert in the flare, so the seam is an upside down Y.

That's called a gusset. Typically you see it on larger bells like tuba and euphonium where there simply wasn't large enough sheet metal available to make a bell of that size, so an additional piece is grafted in to reach the desired dimensions. On a trombone bell, I would suspect that it was made in that way to limit the amount of scrap metal produced per bell. I may be wrong about that, though.