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When I posted (a while back) about doing the best I could manage Minick-influence Conn bass trombone restore job, that was the FIRST of six trombones pulled away from the band dept. by the new-ish (former assistant band director/trombone professor) dept. chairman trombone/professor. He was MOST interested in that particular instrument, being that he himself is mostly a bass trombonist, these days. Being that it was at least forty years old and marched with, it presented me with a good challenge. (Hey...I'm MOSTLY a contrabass tuba player, these days, and I DOUBLE on bass guitar.)

Now that @catgrowlB has properly defined modern-day (B-flat) bass trombones as simply fat tenor trombones with an extra auxiliary valve (congrats on that ), it's time to move on.

I set aside the other five and am working them in between all of these high schools (which are all sort of like baby birds urgently peeping for - instead of worms - repairs).
- as of now: DONE AND DELIVERED two not-very-old Bach 42B trombones (which I used to begin to teach my friend how to repair trombone slides - another thread)
- one RATTY OLD has-been-re-lacquered-and-yet-most-of-that-is-worn-off Bach 42B
- two not-particularly-old Bach 50X (two different config's, but were bought NEW with OLD style "sliding thumb" linkage). He also has asked me to "split" the linkage on these.

Right now, I'm working on the ratty 42B.
I thought I was going to have to replace the (long/lower) inside slide tube (out of stock everywhere), but (the tube was BADLY ovaled right in the middle, and wasn't responding to traditional methods) I tried something sorta crazy which was SUCCESSFUL, so the beat-up old playing slide is now "floating", gently-polished (lots of wear and scratches), lacquered, and back in the case.

The bell AND bell section were totally "jacked", so I'm taking it all apart. The only real dents and creases were in the bell (a few easy ones in the main slide bow) but the bell section was all cattywompus and (well...) some genius had buffed the crap out of the rotor body, so I'm looking at the random Bach rotor bodies I have around here and will fit one of those to the oem casing. ...and the bell section (with gentle polishing - leaving wear and scratches in place) is going to get hit with new lacquer as well.

My (1970's lessons) guitar teacher died, and his funeral is this afternoon (Mrs. bloke grew up four houses down from his wife, so both of us are connected), but I managed to get the bell "looking like a bell" again...but it's now time to get showered and grab a hamburger before jumping in the car.

oh yeah: The bell formerly had a nice curve to it at the main brace AS WELL AS up at the small end (whereby the main slide outside tube was cocked sideways.

I got the bell section put back together, today.
The trick is to take apart as little as possible, because it's really easy to end up with a bunch of tinkertoys...aka IKEA...a trombone bell section KIT.





The main tuning slide legs' alignment was out .030" or so from end-to-end but - at least - coplanar.
I messed with it for a few minutes until I managed (playing with the cross brace) to hit parallel on the nose.

I COULD NOT go any farther without FIRST doing the previous, because EVERYTHING hinges on the main tuning slide.

OK...to remount the bell FIRST, I had to get the zigzag out of ALL of these parts (ie. all in straight line, because the MORE stuff that gets mounted back ONTO the bell section (certainly the bell itself) the more difficult it becomes to head and move other things to where they should be.





Next, the bell needed to be mounted, but the cute little signature Bach diamond braces had to be removed, because the MAIN TUNING SLIDE must determine how the bell is mounted, and NOT those little non-adjustable braces. (Remember, YESTERDAY, and straightened out the bell and aligned it's OUTSIDE main tuning slide tube.)
oh yeah: BOTH ends of the main tuning slide must hit simultaneously (duh) UNLESS someone wants their trombone to look as if it was stuck back together in the back of a music store.





It was now necessary to measure the widths of the two spots for the two diamond braces (bell to F-attachment tubing), and then bloke had to look through his random-spacing Bach diamond braces and find TWO DIFFERENT ONES (not necessarily the ones that came off the instrument) that fit the two places where they belong. (I was able to use the narrower one on the wider space, and I found a narrower YET one in a drawer to go in the other spot. The widest one (from the instrument) was too wide for either spot, so I tossed IT in the drawer. (Remember, the entire bell section is spaced on the MAIN TUNING SLIDE, and NOT on some existing non-adjustable braces.)





WHILE mounting those two little braces, it's ALSO important to pay attention to OTHER geometry, as it's really easy to allow the two F-attachment outside slide tubes "sag", in relation to the main frame of the bell section.





...and when someone RUINED the rotor body when it was refinished previously (30 years ago...??), FORGOT that they left the rotor body in the "bright dip" (chromate solution) and THEN buffed the sh!t out of the rotor surface (to cloak the etching damage done by the chromate), it's time to look through my box of rotor bodies, and pick out one to put in place of the one that's "toast". The one that I put in there turns (but not nicely...YET) and it does NOT rattle in the casing, so that's what they're getting from me as a freebie.
Here's the ruined one... oooooh...SHINY !!!!! (ruined)





Something else is to pull out the PLAYING slide, mount it and make certain that the bell rim clearance is appropriate.
Tastes have changed over the years, so I set the bell rim clearance (playing with the receiver end of the bell section's main brace) slightly farther out than it was originally. I hate to go as far as a FEW people seem to prefer, because it just makes the instrument look (well...) damned UGLY (unbalanced...just wrong).

Tomorrow, I'll fit that rotor to the casing and get to shining everything up. I'm OUT of nitrocellulose lacquer (the proper type for Bach Stradivarius instruments), so I'll probably polish it to a first stage level, stick it in the case, and then polish it to the final stage when a gallon of lacquer arrives.

see...?? It's simple as pie...and all ya's gots to do is do all these stuff as close to perfect (considering that it was beat to hell, the rotor body was ruined, and it was put back together wrong in the past) in a short enough amount of time to (hopefully) make as much per hour as the car repair shops charge.

- the main slide can be moved in-and-out with one hand.
- same for the F-attachment slide
- the thing looks "right" from all angles.
- the rotor - once I get the donor one spinning - will offer a respectable vacuum/compression release (significantly better than some of those gimmick valves for which people pay a lot of dough)
- this one features the old-school (adjustable) rotor linkage, but - of course (from adjusting bike axles when I was a little kid) I know how to adjust it, and I also have the missing lock ring it needs.

I just hit the F-attachment area with a quick pass (much hand-polishing left to do)...It should look pretty nice when I'm done, there are two or three really small dents in the F-attachment tubing left to remove. I didn't chemically strip the lacquer, as it's buffing away effortlessly, so I'm simultaneously (via a quick pass with one of the buffing machines) stripping the old lacquer and knocking off most of the excess solder (from my own repairs).





I fit that donor rotor body into the casing and I'd rate the blow-by as "excellent-for-used" (again, less air leak than with some of those new-fangled trombone valve systems). Check out where someone beat the hell out of the rotor casing. The donor rotor kept catching right there (duh), so (rather than wearing the perfectly round rotor down to clear that spot), I resorted to SANDING (and fairly coarse paper) that spot on the interior of the casing (and then smoothing out the surface with finer grades of sandpaper). I'm pretty sure that's why someone - in the past - buffed the sh!t out of the original rotor body and (though they got it to turn) ruined it. (I'm not charging enough to replace this entire rotor assembly. I do know - however - who has a bunch of low-cost ones though, left over from when they made them for the old USA Blessing company.)





I'm not trying to make this instrument "look like new". I'm striving to completely REPAIR it (while also re-lacquering it, yet with minimal aggressive polishing).

The "rat" 42B is done.
The slide works very well.
The valve is very quiet.
"That old style linkage is always so noisy.*
(People don't understand how to adjust it.)
Everything is lined up.
All the dents are removed.
It's shiny.




I'm tired, and my clothes smell like lacquer.

Remaining from their pile of "professional quality" trombones are a couple of Bach 50x bass trombones.
They just need their slides taken completely apart, straightened, put back together, and their old style "sliding thumb" linkage "split".
These are not old instruments, but newer instruments which were ordered with old style linkage by a former head band director who's a percussionist.

I tried to do two things at once, today.

A college buddy (you know, from the way-back machine), Tony Hudson, asked me to refinish his trumpet before Easter.
I've been putting it off FOREVER, because - probably thirty years ago - I refinished, it, and it still has about a 92%-nice appearance, and (because of the care I took) does not look like a "RE-lacquer" job...but (OK), it's getting too close to Easter.

I used some industrial stripper on it (not that EPA dumbed-down hardware store worthless crap). That stuff separates epoxy from brass (like a loose layer of Saran Wrap) and totally dissolves nitrocellulose lacquer.

OK...I got it stripped, and about 7/8th of the instrument preliminarily buffed (I've done NO hand-ragging, yet...just a quick pass). It's going to be easy, because he hasn't put a dent (not even a scratch) on it. Tony's a great person, and (obviously) remarkably graceful.





AT THE SAME TIME (while the stripper was working on Tony's trumpet), I took apart the first of two of this university's two Bach 50x bass trombone's slides. (These are the last two of a batch of six 'fesshunul-grade' trombone I was handed.)

Before dinner (well...actually a half hour LATE for dinner, but that's not too bad), I got the playing slide back together. I'll polish burned lacquer tomorrow, and I might do some freebie polishing, because (even though this trombone is only a few years old) the lacquer on the slide is VERY spotty. I tend to suspect that some genius (with an ultrasound tank, who felt obligated to use it - due to its cost) decided to put it in there sometime in the past and left it in there too long. (There were a couple of years when a new band director didn't use us to do their summer repairs.)

I was surprised at how many dents and dentletts I found on the outside slide tubes, and how (not terribly, but significantly) bowed the outside tubes were. Both inside tubes (once spun and examined) are judged as "perfect".


This end measures 3.9775 inches:



This end measures 3.9770 inches:



The middle (notice my Sharpie marks, detecting the bowing of the tubes...I'll get rid of those marks with either gasoline-and-a-rag or buffing) measures 3.9770 inches as well:



It wasn't a "terrible" slide, but it's now extraordinary, which is why the trombone 'fesser/chairman sent all these 'bones here.

I went ahead and relacquered most of this playing slide today.

The bell section of this Bach bass trombone is open wrap and dependent rotor with the modern split linkage.

The tuning slide alignment is ridiculously bad and the inside outside tuning slide tubing fit is ridiculously loose. (I'm pretty sure this instrument was built within the last decade, and is reflective of things I've heard others say.)

It appears that at the factory they flared out the ends of the inside slide tubes to reduce the amount of air leakage.

As short as the main tuning slide is, it's out .010" over its short distance of travel. I was unable to pull the second rotor's short slide due to its alignment, so I did some heating and moving around of things so that I could at least make that slide parallel and get it to moving. The long F tuning slide is out about .035" from end to end, but it slides anyway due to it being so flexible and not having any braces. Were I to get all this stuff straightened out, I'll burn all the lacquer in this entire area of the instrument, I didn't quote on this, and no work was requested on these slides, so it's going back the way it came other than the one slide that I did fix (so two freebies include re-lacquering the outside playing slide and aligning the second rotor tuning slide). At least those tuning slides won't fall out or slide in while someone's playing this instrument.
The playing slide really does work beautifully now, and that's what really matters.
Okay, I've only got one more trombone left to go for this very patient customer. It's the one where I have to split the linkage.
I might take a very few pictures...
I like the instrument innovations mom and pop business, but I never find that any of their stuff is useful to me on jobs like this, because I can reuse so much stuff from previous configurations and I can fabricate all the stuff that they would send to me, and their stuff is only partially fabricated anyway.
... I did purchase a first valve slide trigger assembly from Miraphone to put on a 184 (another thread). I knew it would be way over built because they are Germans - and it was, but at the time I just didn't have both the time to precision align that slide, get all the dents out of the slide tubes (because it was an brought back from the dead school instrument that a friend of mine bought) and also design the trigger system and fabricate it
... and I knew - if I bought something from Miraphone - it would be ready to install, instead of like buying all the lumber that I would need to build a house but I'd have to cut every piece.