The Great Kurath Re-Tubing

[bloke]

bumping more interesting post back to the top ↑

[the elephant]

I can finally take off some of the really crappy work that is just tacked in place, clean everything up nicely and reassemble it as though someone was paying me to work on their horn, rather than me dinking about in my carport "prototyping" (head-scratching, measuring once, and cutting ten times, etc.) and being a pig with the torch.

I can also swap back from the huge 5mm torch tip to the 2mm tip I have used for decades. The big tip allowed me to silver braze easily with an air-acetylene torch. I might get an oxy-acetylene rig one day, but do not want the two huge tanks in my carport where they could blow up. I am afraid of my single B tank as it is. Anyway, swapping back to a tip that is more for detailed work rather than disassembly or heating the bejeezus out of something ought to allow me to once again do clean work.

I am taking a break for a while from this. I need to figure out how to connect the 5th to the upper lever and that will require more farting around and materials wastage, but I'll get it licked eventually. After that, I can tackle the 6th system, which I am sure will be a barrel of laughs…

First, some clean-up. I have a couple of gigs in about a week that are definite F tuba books. And I want this to look more or less presentable for them. Besides, I am sick of this horn looking so dang bad.

[bloke]

re-bump

[the elephant]

The machine is affixed to the bugle using six detachable braces. When I rebuilt the 4th slide circuit I corrected some poorly fit things, some from the factory, some due to my realigning the slide assemblies to work better. (The big hoop is the issue, and I had planned on rerouting the 4th circuit, so I did not correct this back when I first got the horn. Now I have decided to leave the routing as it is, so I had to reconcile my changes to that blasted hoop. I really need to bend my own.)

The main upshot of this is that the side of the 4th circuit that is next to the bell is now farther away from it by about a quarter of an inch. I was too lazy to cut new braces, so I swapped in or moved around what I had on the horn and what was in a bag of used ones. I ended up with one brace that was too short. I thought it would be long enough, but the socket is very loose on these, and it ended up getting wired down and soldered in place with the socket/flange being very crooked.

I decided to make a new one. The posts are an oddball size and I did not bother with this before mainly because I did not want to have to buy an 18" rod just to use 1.5" of it. (It is a size that I never use.) Yesterday, for whatever reason flitted through my empty head, I decided to see what I had in my baggies of rod stubs, et voila! there was a four-inch length of the exact size that Conn-Selmer uses for these braces. Cool. I removed the threaded disc from one of my used braces, brazed it to this rod, and cut it to length. I then screwed the brace together, wired the assembly to the horn, and soldered it in place. Problem solved.



I bought this Roburn MT-770 in 2010 and it has been stored away in a cabinet since then, the package unopened. I stumbled across it yesterday and decided to give it a try. I really like this thing and wonder why it took me twelve years to give it a try. I think most of these butane microtorchs are made in China and mostly work (and break) the same, but some research is worth your time, as apparently some of them are absolute junk. Mine was highly rated by a jeweler tool and supply company that I like. So if you have been wondering about these, do some reading and then get one. Highly recommended for all you Franketuba builders.



I love acetylene. I have never used a butane torch like this one because of Hank Hill.

[the elephant]

Yet another idea for connecting the upper 5th to the lower 5th linkage…

This would obviate the need for the drop-bar from the lever, removing most of the stupid issues with multiple arc swings and angles and greatly simplifying the situation. Running a short rod over from the upper lever to the end of the drop-bar was simply to use what was already present. At that time I did not think I would have to re-do the entire system because I did not understand the complexity of getting these two levers to work together in this manner using the preexisting system. Had I simply recognized the need to re-do everything to get this to work, it would have worked on the first shot, as what I am moving toward is becoming geometrically and mechanically simpler with each iteration.





Doing this will allow me to remake the lever (lord help me) in a way that is much easier to do accurately, much simpler, and much nicer looking. So after these two gigs on Wednesday and Thursday, I will do this, because I won't likely need this tuba again until October. And if something quintet-ish comes up in the meantime I can use the 186.

So I may have to redo the hinge tube at the top of the Z rod and I will have to make another T hinge assembly and YET ANOTHER LEVER. However, this will be a very nice, simple one with no convoluted BS tossed in.

This is like being mentally constipated, I have to say…

[York-aholic]

I sure hope that when all is said and done, having the two linkages connected won’t make it feel to sluggish. That will be a fair amount of mass moving back and forth. On the other hand, you’ll have a spring at both levers helping on the return stroke.

Glad it’s all together for the two upcoming gigs.

[bloke]

I sure hope that when all is said and done, having the two linkages connected won’t make it feel to sluggish. That will be a fair amount of mass moving back and forth. On the other hand, you’ll have a spring at both levers helping on the return stroke.

Glad it’s all together for the two upcoming gigs.

https://weisbergsystems.com/

[the elephant]

Yeah, I'll look into that, Joe…

[the elephant]

I sure hope that when all is said and done, having the two linkages connected won’t make it feel to sluggish. That will be a fair amount of mass moving back and forth. On the other hand, you’ll have a spring at both levers helping on the return stroke.

Glad it’s all together for the two upcoming gigs.

The second rod is straight and would not have to withstand any weird stress beyond the small bit of longitudinal compression normal for such a thing. I might use hollow nickel hinge tubing for it. Also, I might remove my homemade lever base from the valves and make one that is wide enough to use the original, heavier tuba spring that worked great.

Regardless, if the second rod is hollow it might be light enough that the two springs together will even that feeling out.

I am thinking ahead right now, and what is bouncing around inside my skull is how to make the throw length of the upper 5th and 6th match. Hmm…

I love thinking about this sort of puzzle unless it takes me too long to solve; then I get ticked off at myself. This lever is one of those cases. I have had to solder down and then remove things so many times that I no longer try to be neat or to clean anything up. The tuba looks dreadful because of this. So my big motivator now is to finish so I can make it look nice again. I believe I will be trying to lacquer the bugle. I am sure it will look like crap up close, like a so-called "ten-foot paint job" on a car. HAHAHA!!!

[bloke]

With the fifth and sixth rotor assemblies on B&S F tubas not being in the same plane – yet their finger spatulas being in the same plane – the travel of those spatulas is not identical, but it is not an issue… At least, I don’t sense it as one.

[the elephant]

I have decided to keep the short throw of 5 where it is, as it will be much easier to duplicate it with 6th. I made it so that 5th is exactly 1:1 (It came to me with a factory throw of about 1.75:1 and my previous new lever was more like 2:1 and a little longer than the piston throw, which was aggravating. I think I can get used to just about anything, so since the current 5th lever moves exactly the same distance that the linkage rod moves (the pivot point is at the tip of my thumb) it ought to be easier to match that with the 6th, once I have an upper 5th lever to compare it to. I think that if I keep what I have that any differences ought to be pretty minimal. If I try to improve what I have, another layer of needless complexity will be added, and I am done with that nonsense.

It'll be fine, I guess. Thanks for the observations…

[bloke]

' sound like you have figured out how do do what you would like to do...

If the 6th throw was shorter than that of the 5th - and you desired a match, simply moving the point at which the link attaches to the #6 stop arm would define a longer #6 throw.

Otherwise, increasing the #5 throw (in the same way) to match a shorter #6 would risk your "just-misses-everything" #5 action arm - once again - clanking against something.

reason for this post: too much caffeine

[the elephant]

The 5th RH thumb lever system is now fully sorted and works really well! I lapped all nine slides (which had not yet been done) and trimmed two that ended up being 1mm long on an inner leg after the assembly had to be shifted a little to line up better with the other slides, and lightly lapped the first two pistons due to the high heat I had to apply to 1st to mount the lever base.

I spent about three hours heating and wiping, scraping and sanding, and polishing a lot of the worst cosmetic crap, so when I actually do this completely, a lot of it will already be out of the way, or at least much less work for me at that time.

The horn plays great, too.

Once I am done with these last gigs going into our summer hiatus, I can then sit down and work out the two upper levers. Then I can get back to enjoying this tuba.

[bloke]

mouthpipe reddish from heat, tarnish, angle of light, or 80:20 brass aftermarket ?

[the elephant]

mouthpipe reddish from heat, tarnish, angle of light, or 80:20 brass aftermarket ?

I had put it in a white vinegar bath to eat up the bit of lime that had built up over the past six years. I think it is 80:20, but that would be out of character for Herr Kurath, who used the cheapest metals he could get, it seems.

As spendy as the Willson tubas have traditionally been, they have usually used plain yellow brass for everything — no nickel silver trim, leadpipes, or bearing surfaces. I think they might use that stuff a lot NOWADAYS, but back in the day, Willi-the-elder did not, as most of his Willson stuff (and almost *all* of his earlier Kurath-branded tubas) were plated. The early 3200s I saw back when they had the Rotax added and were rebranded from "Kurath" to "Willson" and that were lacquered, were 100% yellow brass.

As with Bach trumpets: why spend twice as much on materials if no one can see them under all that glorious silver? So if this leadpipe is of a different alloy it was probably the cheapest tubing of the right dimensions that his supplier had in stock that day.

[Sousaswag]

I think you’re right… my (what I believe to be) early 3200FA-5 is lacquered, with the most terrible lacquer I’ve ever seen, and there isn’t a spec of nickel silver on it, EXCEPT for the leadpipe. Replaced? I don’t know. It is nickel silver, though. The top slide crooks of 1, 2, and 3 have some rot. I anticipate replacing those or patching them when the time comes. Thanks, Willson

If the tuba didn’t play so well I’d complain more… In somebody else’s thread

I’ve very much enjoyed reading your thread here. I look forward to more updates!

[the elephant]

My danged 1st valve was hanging fairly often after I put the horn together yesterday. After some inspection work, I discovered that it has reached the end of its life, lapping-wise. (It had had a ton of work done to it before I ever owned it. The horn had been in a car wreck or dropped downstairs or something to screw it up so badly. And both 1st and 4th suffered damage to the knuckles that enter/exit the piston block. Someone had lapped the snot out of both valves rather than doing the more tedious work of correcting the two knuckles, so a lot of metal was sanded off by them. I remember discovering that many years ago, and I was pissed off about it. Well, they work so well after all that work I did to them that I forgot that they are starting to become loose.

I added a bit of 3-in-ONE oil to the lamp oil I use on these valves and that helped some. However, my inspection also revealed that the plastic valve guides all need to be replaced at some point and that 1st, specifically, had some crud jammed into the little notch with the plastic guide, so it was sitting a bit proud at the bottom (at an angle). I removed it and spent about 10 minutes cleaning out all the gunk, the screw head and threads, and the guide itself. I reseated it and screwed it down and now everything is good.

It makes me wonder whether I like this tuba enough to spend the cash to have the valves rebuilt, and how long I would be without an F tuba while the work was being done, as this would require complete disassembly of the valve section.

Well, rats.

The thing still plays very nicely, so I will probably opt to have this work done, but not for a few more years — it ain't cheap, let me tell you…

[bloke]

Typical honing machines used for this operation can accommodate a front-action valveset with about a foot of tubing or whatever extending out >laterally< in any direction.

It is the top action valvesets that must have all of their tubing removed, because the tubing extends out vertically, rather than laterally.

People who specialize in this work are not ham-fisted, and typically return valvesets with slide tubes still aligned as nicely as when they were sent.

They also charge by the valve, so if there’s no reason to do pistons/casings #’s 2 or 3, you probably shouldn’t have them done…if you’re like me, and it’s not raining money, right now (and the little money that we do have has been rendered virtually worthless by our rulers).

need for an F-tuba:
You’re the guy with the overlapping-purpose tubas; I’m thinking that I remember that you own a couple of 186’s…

[the elephant]

Overlapping purposes: yes. However, I am stupid, so I have a very bad time playing in a quintet on a CC as I have played that same folder of music only on F for 28 years, and the times I have to use a CC require a lot of practice by me, meaning that if it is a milling music gig there will be no set lists until we get to the site, meaning that I have to prepare about 50 tunes that could be called. It is HOURS upon HOURS of work for me to prep for a CC quintet gig that lasts about ninety minutes for an audience who is actively NOT listening to us. It is frustrating to be dyslexic. Sometimes it is worse than others, and I have been in a bad state for about a year now. (These cycles — for me — last about two or three years at a stretch.)

Regarding the hones machines, I will ask Dan O. what he usually needs, spatially. It is very nice that my valve sections come off in one piece, I guess. I could just box up the machine complete and ship it off to whoever will be doing the work.

That is some very useful information, Joe. I had heard that for large tuba valves it was normal to send a bare piston case set with all the valve parts, denuded of slides and ferrules. My valve set for this tuba is too long, so I would likely remove the 5th/6th/small side MTS stuff from the 4th exit port, but I think everything else would fit in that space.

The Holton (same valve maker, two years newer, so also a candidate for a rebuild) would have to have the 4th slide circuit at least partially removed.

[bloke]

yup...always some stuff that needs to come of but - often - easier to take-off/put-back-on that the stuff closer in.

F tuba, then...
Is Jackson a large-enough town whereby there's some sorta-wealthy/really-friendly amateur/hobbyist who bought themselves (hopefully: not a jimbo 600) an F tuba?
...or a 30-something-year-old Southern MS grad (etc.) who still has theirs, yet it's sorta collecting dust...(??)