188 repair, today

[bloke]

arrived at 10 A.M. with three ziplocks of little parts and the tuba in its bag.

The tuba had been knocked over at a church service.

The #4 top (fixed) bearing (engraved nickel - normally lead-soldered permanently in place - the one onto which the cork plate is screwed) was in one of those bags, and the other bags contained various other 4th valve (LOL...designed to be removable) parts.

After checking the rotor body in the casing (awkward to test, but seemed basically OK), I put the top bearing in place (WITHOUT soldering it back in place) and did a bit more testing. It wouldn't turn easily.

best guess: everything pretty much OK...Just solder the bearing back in place and (likely) straighten a slightly bent stem.

...so yes, that's exactly what was wrong. The impact knocked the bearing's solder loose (it was only soldered on halfway around at the factory, but (realize this) that's not any sort of "air-seal" location...It just needs to be there and be secure.

I borrowed some of Mrs. bloke's super-tiny-gauge solder (I hate that crap, but - sometimes - it's what is called for), and soldered the bearing back in place (making damn sure it was squared up). Yes, I burned the lacquer a little bit (not bad), as BOTH the bearing AND the casing are pretty massive (not just sheet metal, slide tubing, or ferrules), thus requiring more time to heat up to soldering temperature.

Once it cooled down (to lazy to get up out of my chair, go over to the tub, and cool it with water...easier to sit there and chat with the customer), I inserted the rotor (again, fully expecting the stem to be bent)...Yeah, the stem was dragging...I could rotate it with a fixture, and pliers, but otherwise it wouldn't turn freely via finger-force.

Looking straight down at the stem (with my reading glasses) I detected a subtle shadow on one side of the stem (where it enters the casing), so I tapped a few times on the OTHER side of the stem - knocking it towards the shadow. ,
Relying on "bloke-luck" (which seems to follow me around fairly often) that did the trick. I could turn it with my fingers...but it wasn't quite "there" (probably would have worked but POSSIBLY would have occasionally hung...

...so I pulled out the trusty LAVA Soap suds and mineral oil (both on the rotor body) put the rotor back in, spun it this-way-and-that (with the fixture and the hand drill), took it back out, cleaned it, and it was fine.

The final test was to install the removable bearing.

After cleaning out my home-brew lapping gook, oiling (lamp oil on the rotor body, and mineral oil in the rotor stems), and putting everything back together, (luckily) everything works smoothly...and the lapping was only about five seconds in both directions, so (again) it was already really close to dialed in before doing that.

Other damage: The only other thing that happened were a couple of "poke" dents on the upper bow's nickel cap. I have this behemoth white-acorn-shaped (oblong) solid dent ball (very strong magnetic pull) and a double (2-inch) magnet (with a greased rag over it) and that huge ball smoothed out those double-layer dents.

This tuba is ready for next Sunday's rehearsal and church service. (This guy is a really good player, who has overcome having to have 100% of his teeth removed, and learning to play again from scratch.) I enjoy his visits...nice guy...and (unlike many locals, because - you know - "That's just ol' bloke") he's bought a few of my mouthpieces.

[tubatodd]

You know the rules. Picture...or it didn't happen.


We are simple creatures and pictures make us happy.

[bort2.0]

I miss my old 188. Now that my current playing has shifted to orchestra again, I'm wondering if I'd still love it as much as I used to. Or if I'd still want to chase down "188 but a little larger" (which I can assure you, does not exist in the way I'd like it to exist)

Joe, as much as I think you'd hate having an apprentice, I also hate to think that this amount of repair knowledge might not be fully put forth to the next generation. So, thank you for taking the time to write all of these things out.

Fast typist or not, it takes some time to do it.

[dp]

I've never seen that top bearing plate knocked off of a rotary horn, but then I'm not a repair guy. Tough repair to take on, when as a finished and functional assembly, that top bearing plates centerline and bore function as the reference features for the whole damn assembly. When knocked loose it has to be replaced without those nominal reference features...so the bore of the casing and then the back plate have to become reference features for re-establishing the centerline within a pair of very closely-toleranced cylindrical features (the in-line bearing bores and the casing bore). Kudos to "the OP" for pulling it off (sounds like anyway) and being able to use ... mere words ... to describe "the process."

cylindricity.png (39.74 KiB) Viewed 661 times

[bloke]

You know the rules. Picture...or it didn't happen.


We are simple creatures and pictures make us happy.

Imagine if you will, a normal put-back-together 4th rotor casing with a tiny trace of solder next to the top edge and some not-too-badly burned lacquer...

[bloke]

I miss my old 188. Now that my current playing has shifted to orchestra again, I'm wondering if I'd still love it as much as I used to. Or if I'd still want to chase down "188 but a little larger" (which I can assure you, does not exist in the way I'd like it to exist)

Joe, as much as I think you'd hate having an apprentice, I also hate to think that this amount of repair knowledge might not be fully put forth to the next generation. So, thank you for taking the time to write all of these things out.

Fast typist or not, it takes some time to do it.

As I've said, I type crap on here when I need to come in the house and get away from the shop, the dirt, to temporarily escape the odors of the various repair-related stuff out there, and (often) when I've come in to text/email/message someone about something important and (hopefully) awaiting a prompt response, so I know what to do next (or hoping for an immediate ePayment for this/that/the other), etc., etc...

@dp
My strategy for getting the bearing right "smack dab" where it was before was to NOT heat and wipe away solder NEITHER from the top of the casing NOR from the underside of the un-soldered bearing. I added (water-like, not paste) flux to both surfaces, gingerly tapped it "home" (using a f.u.b.a.r. trombone mouthpiece and tapping on it with a mallet), and then soldered it back in (again) with Mrs. bloke's small-gauge solder (so as to greatly decrease the chances of it elevating itself via an added layer of solder. (She uses it underneath saxophone posts for the same strategic reason: to prevent solder from elevating a post, and thus creating tension by de-aligning a long steel screw rod.)

Is this sort of thing that probably not too many others could do in a half hour?
Maybe, but there ARE OTHERS who could - I'm quite certain of that...but (were that tuba mine) I wouldn't want anyone else (not anyone else right around here) fixing it.

again: I'm a "results" person. I don't particularly relish "the journey". (ie. I don't live in the moment; I tend to live in the future.)

Does it HELP to be accustomed to (for 46 years, since I first began staring at them, and having not had a clue) staring at barely-bent piston valves and barely-bent rotor stems? ...and does it also help to have had a Mom who was a commercial artist who taught me about seeing/drawing straight lines and circles "free-hand"? of course...all of that..."life experiences".


skills: We trade them back-and-forth, don't we?
(a better idea that trading Chinese crap back-and-forth)

To me, this isn't "interesting".
To me, the "interesting" part is that it was NOT a hassle.
The MORE interesting part was that this guy (someone I like) had a reason to come see me.

[prodigal]

We find it fascinating!

Thanks for getting a great tuba back in shape!