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This rather smells of a horrible translation from whatever language. A 12mm bore of a trumpet would be on the large side, but hardly the largest seen. A bell diameter of 124mm would be very normal.

Klaus

ben wrote:Ex... Bell : "CHORUS" type, diameter 12 mm flare, rounded at 124 mm (silver brass 703)

This is from a Conn-Selmer Trumpet, what exactly is 12mm measuring. What do they mean by rounded "at" 124mm, is that the distance from the leadpipe?

Curiousitys...

I'm with Klaus on this -- a not-so-good translation with odd (and/or misplaced) punctuation obscuring the meaning. I would think that

Bell: "CHORUS" type
bore diameter: 12 mm (0.472 in)
flare diameter: 124 mm (4.882 in)
silver brass 703

might be more accurate (and make more sense).

In your Alexander example, I noticed something that made sense to me -- in

Bell flare Ø 450 mm

the "Ø" likely indicates diameter ... thus becoming

Bell flare diameter: 450 mm (17.717 in)

Hope this helps!

ø really indicates diameter in this context. In my language and in a few more it is as letter often transliterated to oe by others, whereas the Swedes and Germans have it as ö. In international math Ø indicates an empty set.

Why have international English-spoken web forums very few, relatively, members from certain other countries? In some cases because English is horribly badly taught there. In other cases because some governments make it a policy not furthering English as a second language.

Here is the source of what Ben read:
My translation starts right of the mouthpiece:

Instrument
Trumpet in Bb Chorus 80J
Gold lacquer (GO)
Tonality: Bb
Bore: ø 11.74mm (medium bore)
Brass bell with a rim at 124mm
Start of bell: ø 12mm
(The rest isn’t relevant here)

Here is what the French auto-translation offered for for Ben to read, because he, naively maybe, clicked the English banner:
Not that I should be roughing Ben, but I have juggled languages all my life, and I have been confronted by hopeless translations on a daily basis. One lesson is that no translation is better than the interpreter’s technical understanding of the given matter of discussion.

The French original faithfully is specific about the transition from the valve block into the bell, where one would assume the bell to set off at the bore of the block, but where this model appears to have some conicity in the exit knuckle. This is opposed to the old Benge Claude Gordon model, which had a large bore through the block (12mm), whereas there was a slight constriction at the entry of the bell.

Klaus

As a trumpet is cylindrical nothing starts to flare until the bell. I would read this as the 12mm bore on the trumpet. Therefore the small end of the trumpet bell bore size is 12mm.

My mandarin is what you call a tangerine, and I am allergic towards it. I am not allergic towards my Russian, as I don’t have one.

But as we see, not only Chinese do funny translations into English.

Klaus

I work with an Indian vendor on a daily basis for work. We're both speaking English, but man, is it difficult sometimes!

I could not be certain without more info or seeing this instrument but, I would say this is a "dual bore" design. Many trumpets reach their bore size at the start of the tuning slide and stay at that size through the valve block. Some others, and Selmer is a common example, taper the diameter of the bore through the bow of the tuning slide - what could be termed "flare" and giving a second or "dual" bore size.

The French measure the bore like we do, the inner diameter of the 2nd slide, and there is no indication of an increasing bore through the block. The bore is 11.75mm. There is no mention of any flare in the French text. Départ pavillon means, where the bell starts. In the horn community at least the term therefor is bell tail (the tip entered in ferrule).

Klaus

ben wrote:This is the meat of my question... how do manufacturers describe rate of expansion in the bell.

With a photograph.

And sometimes also with an adjective.

Rick "who has never seen a specified measurement for the shape of a bell flare" Denney