uh-oh... broken sousa piston

[eli]

So I finally bought a snake and cleaned out my old 1929 Conn 32K.

While I was handling the 3rd valve piston, the center 3//8" or so of the top disc broke away from the top disc of the piston and fell into the hollow at the top of the piston. So what I have is the stem screwed into a lump that is trapped inside the hollow of the piston, with the stem flopping around loosely. Oddly, I can't pull the lump up to be flush with the top of the piston -- the lump's edges, and the hole's edges, are somewhat rough.

The easy answer for a repair would be to simply buy a new piston, but how likely is it that a new piston would fit this old girl? Can the piston be repaired? I'll be happy to send photos offline to anyone who has any advice at all.

Thanks,
-- eli

[iiipopes]

If it's a standard .734 bore, it's the standard block that has been made for over a century and a quarter, and there should be lots of used pistons out there that would "fit." Being used, of course, wear patterns might be different, and it might need to be replated and lapped in anyway.

All of the repair & restoration forum members who know more about this than I do should post and correct me on this if I am wrong.

But the main reason I posted is I feel for you -- I'd feel horrible if anything like that happened to my souzy! Good luck!

[eli]

The quote at the Conn Loyalist says the 32K is essentially a lightened-up 38K, so perhaps there's hope for me!

Anybody have a 3rd piston they could part with?

[WakinAZ]

I would PM TubaTinker, bloke and maybe e-mail Matt Walters through the Dillon Music website http://www.dillonmusic.com/

[eli]

tangent comment: The 32K is more of a "beefy" 14K than it is a "light" 38K... The 32K has the "4/4" body, whereas the 38K has the (like 20K) "6/4" body.
_____________________________________

Wow... honored by a direct response from the one and only bloke!

Not arguing with you (wouldn't dare) but here's an excerpt from the Conn Loyalist site, which is itself a quote of Conn's literature:

"What Conn said in 1936:
The 32K Lightweight Sousaphone is the newest thing in sousaphones and was designed for a light-weight sousaphone possessing the same general design and quality of performance as the 38K Sousaphone Grand. That this model fulfills this demand is fully evident because it has jumped into immediate popularity. Magnificent tone easily produced, combined with lighter weight than found in the average BBb sousaphone, makes this instrument ideal for professionals with long and tiring engagements... Although of the same bore through the valves and major portion of the tubing as the famous Conn Sousaphone Grand 38K, our engineers have ingeniously designed the instrument in respect to rings, bracings, ferrules and valve caps so as to reduce the weight by more than two pounds, making it weigh about 26 pounds. The bell is 24 inches in diameter."

I can see from the photos at the Loyalist site that my horn's body is indeed smaller than the 38K's (most apparent at the upbend to the tenon). On (yet another) tangent, I've been assuming that my horn's valve section bore was the same as a 38K, which (again according to the Loyalist listing) is a #10 bore, or 0.7188". Am I mistaken? I happen to have my horn with me at work today and am surrounded by engineers with micrometers. Is bore properly measured at the inside diameter of the 2nd valve tuning slide?

Thanks
-- eli

[WakinAZ]

Is bore properly measured at the inside diameter of the 2nd valve tuning slide?

Yes.

As far as the relationship of the 32K to other Conn horns, Bloke is saying, I think, that in reality/practical application, the 32K is a more strongly braced 14K (same wrap, bell size, valve set) regardless of what the Conn sales lit said in theory.

Eric "former 32K owner" L.

[iiipopes]

OK, please keep these bits (pun intended) in mind:

1) #13. Remember, bloke has worked on more horns than some workers, even long term workers, at the musical instrument factories have ever made.

2) After MacMillan bought Conn, they destroyed all the old corporate records so they did not have to be moved. As good as the Conn Loyalist is on finding pictures and other resources of historical information, remember that the web site is an attempt at reconstruction of lost historical data, and as are all such attempts, variable in its success, and open to revisions as new data becomes available.

3) Remember further that facts will always take a back seat to marketing literature, Conn included, and especially so now that Conn is an assimilation of the cyborg.

4) Conventional wisdom is that the standard Conn souzy block is .734 bore on almost everything BBb, regardless of what other sources may say, and irrespective of how index bore numbers may have been labeled or derived.