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I've had nothing to do for the past few days, so I decided to check the bore on my old Martin. I searched the archives, and found advice saying to measure the inside diameter of the male branches of the 2nd valve slide.
Using that, it came out to 17cm/.669". Without seeing the horn (and assuming no mathmatical errors), would this be about right?
If it is, does anyone know other horns with a bore size of the same that come in front action piston with 4 valves? (or does anyone have a spare valve of this size laying around)
Ideally, I would like to put this on myself, but for the sake of my tuba, I would bring it in to my repairman so if there's any way to save money, that'd be greatly appreciated (for example, if the horn is trashed, but the valves are intact)

The bore hardly is 17cm, which equals the bell flare of a small tenor trombone. 17mm equals 0.669".

This bore may be found in smallish CC and BBb tubas and in medium small Eb tubas especially of older models.

Klaus

Hey, not my fault this country isn't metric...
I meant mm
and I just went back and remeasured again..and it came out to 18mm
So, in inches, that'd be .708

That bore is more likely for a contrabass tuba, yet it for some reasons isn’t as common as the closest larger and smaller bores of 18.5mm/0.730" and 17,5mm/0-689".

As I have been told it, NASA is entirely metric since some years.

Klaus

When I go out tomorrow, I'll see if I can find a set of calipers...I'll also check with my neighbor (he'd likely have some)

I don't know if this is relevant. But... I have a Martin 'medium' Eb sousa here that has a bore of .688" (17.5mm). If I wanted to add a 4th piston to it, I wouldn't have a problem using a casing and piston from a King 1240 or 2340 tuba.

imperialbari wrote:As I have been told it, NASA is entirely metric since some years.

A) You've been told wrong: NASA's scientific, engineering, and technical personnel use the metric system internally; the English system of weights and measures continues to be used by all other departments, including procurement, and for non-research related purposes.

B) NASA's workforce represents less than .5 of 1% of the adult population of the US, so its usage is hardly representative of US usage generally.

pgym wrote:

imperialbari wrote:As I have been told it, NASA is entirely metric since some years.

A) You've been told wrong: NASA's scientific, engineering, and technical personnel use the metric system internally; the English system of weights and measures continues to be used by all other departments, including procurement, and for non-research related purposes.

B) NASA's workforce represents less than .5 of 1% of the adult population of the US, so its usage is hardly representative of US usage generally.

It's interesting you mention this. It's quite true.

I worked with English and metric 'double dimensions' for years in industries involving about everything from hamburger patties to automotive components to pharmaceutical items. But... one thing I've found VERY interesting is the inclusion of English machined components on things I would never have expected. .... Like German tubas! It seems as though much of the 'Western' equipment left behind after WW2 is still being used to make parts... especially threaded hardware.

To my knowledge no significant amount of Western equipment was left in Germany for the Germans to use. The Imperial dimensions found in German made tubas much more likely are there because US equipment and tools were moved to Germany (read Böhm & Meinl) to exploit the then cheaper labour in making “American” instruments. This was the York Master scheme with later influence on some of the Marzan models.

Klaus

imperialbari wrote:To my knowledge no significant amount of Western equipment was left in Germany for the Germans to use. The Imperial dimensions found in German made tubas much more likely are there because US equipment and tools were moved to Germany (read Böhm & Meinl) to exploit the then cheaper labour in making “American” instruments. This was the York Master scheme with later influence on some of the Marzan models.

Klaus

It's really just a matter of terminology, Klaus. The equipment was not abandoned but purposely left in Germany during reconstruction. I'm not interested in the political aspects but only pointing out the fact that there are English machine threads on some German tubas to this day.

On the flip-side.... spark threads in American automobiles have been metric for many decades.

(1) My cousin who restores antique cars told me why spark plugs all have metric threads; it's because the only plugs that early auto makers could find came from France. To this day no one has chosen to challenge that convention.
(2) The front brakes on my 1990 Dodge Caravan are held together with metric-size bolts. I am still trying to get the soot off my fingers from that job.
(3) Didn't Nasa lose a spacecraft on the way to Mars a couple of years ago because of a Metric/English conversion screwup?

I believe the bore of the old large Martin BBb tubas was .710 inches. That is about as close as one can get to 18 millimeters.

I always thought it was @ .730, but whats a couple hundredths among friends?

iiipopes wrote:...whats a couple hundredths among friends?

Half a millimeter?

Art Hovey wrote:Didn't Nasa lose a spacecraft on the way to Mars a couple of years ago because of a Metric/English conversion screwup?

They didn't lose it, exactly; they know it's likely somewhere in this universe...