The Great Kurath Re-Tubing

[the elephant]

I had a true visionary for a teacher, and he started me on open hole tuba at the age of three, mainly because I had beat up all the other three-year-olds in my Suzuki violin class and was asked never to return.

True story.

[bloke]

[the elephant]

I had not seen that one in years. I always wanted to hear it without the overdubbed "translation". What were they actually saying? Was it gibberish, or was there an additional script that only they got to hear? Or were they just talking about what they had for lunch that day? I am betting that the undubbed original is funnier than the final product.

[bloke]

I would seriously doubt that any of those actors were particularly well-versed in speaking Leutonian.

[the elephant]

DING! Lever's done!

Here are two photos to show what I ended up with, and a video will be in the next post to show why I dislike it and will eventually make it again.

[the elephant]

That video done dropped, baby…

[York-aholic]

Nice triangulation, but yeah, I see your point.

Next time…

[the elephant]

I thought I would try to save some weight because when it is linked to the other 5th lever I think it will be slow and heavy. Maybe not, but I really don't know. Anyway, using such a thin rid stock to build this lever was a mistake. It works very well, but I hate using squishy-feeling levers. I have had a number of tubas with these from the factory, and I swore up and down that any levers I build would be very rigid and have a solid feel to them.

So yeah, this was disappointing, but I am very happy with how the lever fits and functions. The issues are how far out of line the hand position is to the stop arm on the rotor (front-to-back) and the distance from the connection point of the link arm to the thumb pad. I need to really rethink this to see whether I can reduce these two things. A side-rotating lever is one answer (and is what is on the Willson 3200 tubas), but arthritis in my thumb makes levers that roll sideways painful for me to use for more than an hour of playing at a stretch. I really wanted to replace that with a better lever, but given the constraints, I may have to knuckle under and copy Kurath's design. I guess he had the same issues and came up with that design after a lot of fooling around like what I am doing, and decided it was the best option.

I'm still not convinced I can't figure this out to my own satisfaction, though.

I'll keep working on it.

[Rick Denney]

Wade, attach a spline along the length of that rod. Just a flat piece maybe 3/8 inches wide brazed on edge to give it web stiffness. Either top or bottom will work (not front or back). You’ll still have wrist but it will stiffen up the bending.

Use it as a custom nameplate if you think it looks like a bandaid. “Custom Work By Pachyderm” or something.

Rick “round sections are not stiff in bending by design” Denney

[bloke]

Perry Mason was on last night - when I ran your video (with the sound off), but the video portion was demonstrative - and your complaint was pretty clear.

Maybe I'm really lazy (as previously admitted often), maybe (from being old) I have a bunch of misc. crap laying around, or both...
but here's a close-up of the Holton B-flat.

I'm so damn lazy that I reused a not-worn/not-damaged chunk of a single horn lever carriage and one of the actual levers - chopped down to suit the need. The lever arm is tapered/rectangular nickel silver, and is stiff. Someday, I'll file all of this down "pretty" and buff it (etc.), but it's just not my style (ref: lazy) to do any of that before the entire instrument receives a finish (ie. "buffing is buffing"). (Plus, the part that extends downward to the link is going to be simplified/streamlined as 3mm round steel - with threads, a nut, and a riser for the link, anyway, so...)



I didn't even fabricate a flange or arm to attach that lever saddle...
One of the two arms (attaching it to the French horn) was bent, ground, and reshaped so as it would wrap around that valve casing.
It may not seem "mitteleuropäische Manufaktur - stark wie ein Stier", but - in fact - it's plenty damn strong.
The thumb ring support was scrounged (and cut down) from one of those horrid Jinbao 600 Mira-lookin' F tubas, and the already-with-threads-attached nickel silver thumb ring (ridiculously expensive) is for a Yamaha marchin' contra, but - well - no green thumb.

Something that's in a drawer here is a bunch of old Bundy bass clarinet keys.
Unlike sax keys, (yes, they are nickel plated, but) they are fabricated of nickel silver.
If you would like a chunk of one of them, lemme know...but you'll probably want to clean off the plating.
Otherwise, here's a huge chunk (no plating to remove) for $15 and postage:
https://knifemaking.com/products/nickel ... r-barstock

Rick's suggestion is fine, but (yes?) it's probably just as easy to start back at the hinge tube, and just redo...and the angle brace (probably) won't be necessary. (In my view, it's always best to keep mass/weight to a minimum, and - rather than bolster - just redo. I'm pretty sure - having read your posts - that you agree.)

[the elephant]

Thanks for the comments, Rick and Joe!

Wow, if my lever could be that short it would be much easier to make. In fact, it used to be that short and it worked perfectly, without perceivable flex. The issue is the length. It is about four inches long and I used rod stock that is too thin for the application. I like Rick's idea of a spline but would need an illustration as I am stupid.

The distances for this lever are unreal. I have fussed over this for some time. I may have to copy Herr Kurath's Willson design (or spend $$$ for the parts from him).

I have never had to deal with a lever that is this long and "rangy". The photo of it is just after having been in the pickle to remove the silver brazing flux, so it is all pink and gross-looking. It is also before I added the bend between the hinge and the platen. Uh, and the bend to the rod with the screw in it because I mismeasured it. (Whoops!)

The main flaw is that it is round rod that is too thin.

[the elephant]

Joe, I'm eating lunch as I read your and Rick's comments. Your photo gave me an idea about using bar stock. I have some of the needed thickness. After lunch, I am going to see what I can come up with using that stuff.

ALTERNATIVELY…

I have a bunch of very nice 303 stainless 5 mm rod and the silver brazing rods (45% BAg-5) and flux needed to make a lever out of that stuff. It is a good bit thicker than what I used, and even though SS is pretty soft, I think that 5mm SS rod would be a lot more rigid than 3.5mm NS rod. (I am running out of rod stock in all sizes and it will be a while until I can get more, so the SS presents itself as a possibility, as it was purchased for some other project and then never used: it is literally taking up drawer space for no reason other than I won't toss out brand new stuff.

Round rod — problem
OD — problem

Switching to a stronger material, using thicker rod stock, or switching to bar stock of the same material could help this.

Also not considered — I likely over-annealed all this stuff in the process of silver brazing it together, as there are five joints in a small space. That would at least partly contribute to the lever being visibly flexy.

[Rick Denney]

It makes sense to use one piece when the thickness needs to be consistent across the piece. But the stiffener I'm talking about doesn't need to be 1/8" thick or thicker. It can be quite thin and still do the job, and will be lighter than a single piece (if weight is really the concern).

But this is a problem with lots of solutions.

Wade, the principle in both our suggestions is to use something that is wide in the direction of bending but narrow otherwise, meaning that thicker rod will not be as stiff as a rectangular or web-reinforced design unless it has the same width in the bending plane, and that really will be heavy.

Rick "round sections are not efficient in terms of stiffness/weight" Denney

[Rick Denney]

...
Also not considered — I likely over-annealed all this stuff in the process of silver brazing it together, as there are five joints in a small space. That would at least partly contribute to the lever being visibly flexy.

Disagree with you here, Wade. The annealed state has no effect on material stiffness--it only affects the yield strength. If you can't deform it permanently by aggressive use of your thumb, it's strong enough, even though annealed, and even though it is not stiff enough.

Rick "stiffness and strength tain't the same thing" Denney

[bloke]

' no need to pile on Wade, but - just in my personal experience - nickel silver (aka nickel brass, or whatever someone chooses to call it) doesn't soften very much when the same process is undergone which typically softens yellow brass.

bloke "I don't know very much...I've just beat on too damn many horns. "

[the elephant]

Well, that was six wasted hours and I don't know how much wasted materials and supplies.

I hate how bar stock levers look. This ain't no student model Amati. Ugh…

I am ready to order some quarter-inch rod stock and start afresh. I think I am going to try a fat-boy lever to match the fat-oy ring and bracket. It would only be in keeping with the rest of the horn.

The lever I came up with still flexes, and I SWEAR it is not flexing. The answer? The upper end of the hinge bracket is still floating in space, not tacked down to anything, and it is a very flexible grade of brass. Its flexibility was a major issue in trying to get it back onto the slide, as documented earlier in this never-ending tome.

So at least part of the solution is to replace that bracket and cut one that better matches the distances and angles I have to work with. I am in control, so I need to stop allowing this inanimate object repeatedly tell me, "No." Making a new bracket for the lever hinge will neaten up several of my issues and make going forward much easier. Until then, I will retain my Gumby lever and keep my blasted mouth shut until I have what I need to do this correctly. I have been half-a$$ing all this to save a buck or two. But that bracket is possessed and needs to be melted.

Here is a pic of the most Soviet Bloc-esque thing I have ever made. I can hear the Czech accent that it must speak with…

It went together very nicely, especially the hinge tube. I was pleased with that much. But then I tried to make it "nice" by putting a curve to it. I have neither the tools nor the skills to eyeball that shape with a Dremel tool with a sanding drum on it. I just don't.


The red circle shows where I had to hog out more material once I had it on the horn to check its fit. The lever could not go downwards enough, so I had to sand that notch out. The whole thing looks like crap and I hate it. ONWARDS!

[bloke]

Sleep on it.

We can't be completely pleased with everything we do.

After all: It's not a tube, so it's off-topic.

[bloke]

What you REALLY need are some curved pistons with curved valve stems.

That way, this lever wouldn't need to be so long.

bloke "Don't forget to drill curved holes in the top valve caps, and tap the top valve caps with curved threads."

[the elephant]

I slept on it. I am currently sitting through a university graduation gig. The processional is done and I have like an hour of sitting here to think and type.

My solution is based on the twin factors of the flexibility of the soft brass lever bracket and it’s distance from where my thumb now lives; there really is no good solution using this bracket in its new location. The spacing of everything dictates that what was on the horn is the best solution — if you don’t have terrible pain in your right thumb. But I do.

That leaves me with two options I strongly dislike, and of those, making a bracket to mount to the 1st casing seems to have some merit, though having ANYTHING mounted to piston casings is something I dislike so much that when I have bought tubas with that setup I immediately replaced it with something else.

Anyway, IF the space exists I will consider that as the better option. After my gig I’ll take a look at it.

The other option is to build a thumb ring “wing” with the lever below it, as the Wilson tubas use. I might just buy a complete set of the needed parts so they don’t look homemade.

I don’t know. I’ll have to think about it. Regardless, I am NOT moving the hugely improved thumb position, which is making a tough situation even worse.

[bloke]

When scrolling back and taking a second look (based on your "possibly-not-braced-enough-saddle" situation), It immediately occurred to me to additionally brace it to the #1 casing - just as has occurred to you. It's a pretty obvious solution.

Though slightly bulky, you could lead-solder-or-silver-braze a matching geometry solid brass rectangle on to the back of your saddle (grinding a curve into it, to fit against the casing...I really don't believe that you would want an additional sheet metal flange against the valve casing, correct?)

As far as looks are concerned, I promise to not look at it, and - I suspect - nor will your music director nor (though devoted, and wishing to know absolutely everything about you) your devoted patrons.



Otherwise...
Why not remove some a pair of those Jinbao rotor bumpers off a junk-box Jinbao rotor, and install those bumpers into to that Miraphone 5th rotor's cork plate? That way, you won't be able to determine the exact source of the mushiness.