The Great Kurath Re-Tubing

[bloke]

What would happen if you just removed that saddle, ground a curve into its side, either added a flange or not, and moved it south to the top of the valve casing. Would the hinge point matter all that much, as long as the end of the lever ended up meeting your thumb?

[the elephant]

Won't work.

A straight rod from that location is way too low to allow for the drop rod, which is a lot more important than the lever itself.


Building a really tall saddle would work, but then the throw length of the platen would be huge.


I'm working on it. I will win. It just will take me some time. The obvious solution is what was on there in the first place, which neatly takes up all that horrible, flexy length: A reverse "puller" lever. But I need the linkage rod's action to be downwards for the eventual lefthand lever. A "puller" is what was on there and I reversed it to be a "pusher" type of lever. In this setup, it needs to be a "puller" — but that would negate the use of a pusher upper lever.

This is the best mechanical solution, but it won't work for my application…


I am beginning to see that I need to delete the RT lever altogether, but I am worried about jumping into a whole new 5th valve world cold turkey. That would require many additional hours of *practice* which I am trying to avoid. I need the 5th to be operable by both hands for right now. This is causing me much heartburn.

I may ditch the right thumb lever for now and rig up the two lefthand levers, then try to scab a temp lever onto the RT. Oh, wait. I already have that, heh, heh. There you go. The answer is to ignore the flexy nonsense, move on, and rig up the LH lever.

[bloke]

The green position is where I attached mine on my Holton. As I described, it’s one of the two beefy-yet-small tapered brass tabs that was originally connected to a single horn lever saddle to solder it to the instrument, and was just reshaped to wrap around that interior curve of that valve casing. It’s easy to be skeptical, but it is strong as a rock.
sidebar:
I truly believe that my innate laziness and lack of industriousness pays off quite often (possibly even in workarounds - to reduce the amount that I have to practice to master “hard licks“, even though I’m not talented…??)
Taking one last look at your pictures, I suppose you could take the “over and down“ route, but I understand that would define a wonky appearance.
OEM Willson thumb triggers are notoriously awkward…and damned expensive for the POS they are. Surely they struggle with all the same issues, based on their “really just designed for a four valve system only” valveset configuration.

[the elephant]

As I said that location won't work at all unless I want to make this weird, curvy, complex lever. The angle of the ring is the only place where I am not in constant pain. The swing from where I am is not good. Where you would put it won't work at all, both with the swing angle and getting the drop bar down to the link rid, which is nearly 4" below/rearwards of the lever itself.

I made nine levers today, None of them worked out for the drop bar or the swing. None. Only what I have now works, but it is very thin and flexy, so I need to remake that design using much heavier materials.

[the elephant]

Yeah, what I have works best, though the swing arc does not line up with the thumb ring all that well. So I will definitely make a new one with more robust material.

Man, I have fussed over this one thing more than anything on any of my horns. The location of the thumb was *that* bad. Now that that is fixed the lever is proving to be a real a$$-kicker of a set of parameters. There literally is *no* good location unless I do major surgery to the horn. Ridiculous.

I'll start on this later. I feel very bad. I played at a local university's graduation on Saturday and am now heading in for another COVID-19 test because I have like eight of the twelve listed symptoms. I have been snuggling and cuddling with two of my cats. I hope I have not killed them. That would suck.

Cross your fingers for me. Of the three times when I thought I might have this crap this is by far the worst. I hope it is just allergies/diabetes/physical injuries/etc. all happening at the same time. I can smell and taste food, so that is a good sign.

Back on topic, I am going to try out something new for this lever. It might be great or it might suck or it might be completely "meh". I have never worked with this material in this context, so I will be learning something from this process, which is one of the main reasons why I bother to do all this extra work.

[bloke]

Is the oem routing impossible with the addition of your 6th rotor-and-linkage?
(I believe I'm seeing that their sprung lever hinge tube is parallel to the bell rim, rather than parallel to the valve casings.)

If - any any way - your plate is any sort of obstacle, might you consider the crappy/bloke lever-saddle-mount strategy for your thumb ring?

[the elephant]

OEM is a puller lever and I redid the stop arm and lever to be a pusher. It has to stay a pusher to work with the new, upper levers.

I got it. ;-)

[bloke]

If you happen to decide otherwise, I might (??) have an "opposite" stop arm in my junk, and/or might be ordering from them again very soon.

[the elephant]

Thanks. I make those all the time because I can’t seem to stop messing with rotary valves. The issue is not the stop arm. It is the layout of the tubing as per Herr Nirschl’s design.

The photos are quite illustrative; have you looked at them?

[YorkNumber3.0]

.

[the elephant]

That would increase the throw distance of the lever, unfortunately. It is already too long (and at the incorrect angle). I have to scab something together, and my nifty thumb ring base may have to go.

[YorkNumber3.0]

.

[bloke]

push button, connected to blue tooth - with a couple of wafer batteries (or solar panel clamped to the bell)

[the elephant]

Okay, after several days of consideration and many "dummy" levers made to test the swing arc and throw, along with other issues related to the bendiness of the current lever (bendiness?) I think I have all my solutions lined up like ducks in a midway arcade.

Joe, I *can* use the French horn parts for the lever bracket. Your suggestion to place it atop the 1st casing and my idea to place it on the inside of the 1st casing both created issues that would have made either the lever unusable by human thumbs or place it so the drop bar to the link rod on the valve could not be accessed.

I really like the idea of putting a small bracket on the casing now, despite my reticence to do so in the past. However, we both were looking at the wrong location for it.

The bracket needs to be on the BACKSIDE of the 1st casing. This moves the pivot point to where the swing path of the lever does not shove it really far from the thumb, as my current lever does. This will not really lengthen the lever, either, but it will require a much sharper bend in the middle.

The solution for the bendiness issue is to use thicker material. I have not decided on my three at-hand choices, but I have practiced brazing some 5mm 303 stainless steel rod, and it is not all that different than the nickel silver. I am using the same Harris "Stay-Silv" white paste flux and switching from my normal "silver" wire (yeah, I know, not actually silver) to Harris "Safety Silv 45" (BAg-5) brazing rod. It works very well, too. And — so far — it seems to be much stiffer than the 3.5mm nickel silver.

@Rick Denney and @bloke — I know that round bar is a lot more noodly than flat bar, even when thicker, but as far as longitudinal twisting will this 5mm 303 SS be better than the 3.5mm NS? I know it is a lot less bendy, but how about twisty? I have not yet taken the time to build this lever in this material, so I can only guess at the results. I do not have any flat bar SS at all.

My two other alternatives are 1/8" flat bar NS and .25" round NS bar.

Any suggestions from either of you? I am pretty sure I want to use the design in the photo below, as it is the simplest of the nine I tried, and I know I can make it accurately. It has the least change in distance from the thumb tip along its arc of travel, and still allows the original 5th link arm to be used with the modified stop arm on the valve that is already dialed in.

So I am looking for suggestions for changes to the bracket location or lever shape that could improve it, or suggestions regarding the material to remove some of the squishiness after the valve's stop has been hit.

Thanks for all the suggestions so far. Let me know where to mail the milk and cookies in payment for your consideration.

Oh, the thumb ring is supposed to be at about 11:00 but is at about 10:00 in the photo. It will be slightly more upright when I play the horn, which makes a difference when setting up all these angles…

[the elephant]

The lever saddle will be a section from an old beater Conn 4D horn. The horn is toast, but the part looks almost new.

[bloke]

That looks REALLY good...

...but blue tooth is still better.

51000 phosphor bronze might offer near the stiffness of 304 stainless, and might (??) be easier to braze.

(Maybe, ask @Rick Denney...(??)

I also have trouble finding this in small quantities, and it's not cheap.

You can also arc that "best solution", just in case it ends up crowding your valve casing.

[the elephant]

Ah, I have no phosphor bronze here, but I have five 250 mm lengths of 5 mm 303 SS sitting on my bench. So that is a no-brainer for me.

I think the bendiness will go away, and the relocation of the lever saddle will improve a lot of stuff.

[the elephant]

Side-by-side, current and proposed…

1. Yellow circle, at the elbow in the lever, the drop bar travels toward the 1st casing, and as you can see, had to be bent outwards a bit once I made it. I located it based on where it would start its travel, then discovered that *after* the travel the long, brass linkage rod would go CLACK and the valve would not fully rotate. Dammit.
2. Green circle, at the thumb bar, the bar pulls away from the thumb bar as it swings downwards. Dammit. All of this is due to relocating the thumb ring to where my hand needs it to be.



1. Blue circle, at the elbow in the lever, yeah, I did these at different times, so my colors got messed up. Whoops! Anyway, the arc of the drop bar now takes the brass linkage rod away from the piston casing, and locating the drop bar will be much easier to get right the first time.
2. Yellow circle at the thumb bar, the bar now travels much more closely to the angle the thumb moves. Note that the thumb ring is not as upright as it will be when I play the horn.

[Rick Denney]

Stainless steel (depending on alloy) has a stiffness of about 28,000 ksi, and bronze is only a little better than brass (19,000 ksi versus 18,000 ksi).

Again, regardless of strength. Chrome-moly steel has two to three times the strength of stainless steel, but is only slightly stiffer at 30,000 ksi. Heat-treating and cold-working would both harden the CroMo, making it stronger, but would not increase its stiffness at all.

Ksi = kips/in^2 = 1,000 psi. The above numbers are the modulus of elasticity, or the ratio of stress to strain. 25,000 ksi means that 1000 psi of stress results in 4% strain, or a deflection of 0.04 inches per inch (only meaningful as a dimension in tension).

But comparing with nickel-silver depends on the alloy. Monel, for example, is only slightly less stiff than stainless steel. Leaded nickel-bronze is close to brass, but stainless steel is often a nickel-steel alloy.

Stiffness in bending varies as the fourth power of the diameter for round sections. 5mm rod will be more than 4 times as stiff as 3.5mm rod of the same material. If the material is 1.5 times as stiff, make that over 6 times as stiff.

Torsional stiffness varies by the cube of the diameter, so 5mm rod is a bit less than 3 times as stiff as 3.5mm rod of the same material, or over four times as stiff if the larger rod is steel and the smaller brass.

Diameter has a bigger effect than material.

Rick “why fat-tube bicycles of low-stiffness aluminum can be stiffer than narrow-tube steel bikes” Denney

[the elephant]

Tasty stuff to chew on, Rick. Thanks!

If I go the route of 6mm NS or 5mm SS I will consider drilling it out to make the hinge tube of the same material/OD. I think one of the weaknesses of my current lever is that I am using a generic woodwind key hinge tube and drill rod from Allied. I think they are simply too thin for tuba levers unless they are quite short in span. This tubing is smaller than what Miraphone uses, and the drill rod is a lot smaller. I have no flex issues on short levers, but this has been an issue in the past on anything longer than about three inches, so I obviously need to source a heavier tube paired with a heavier drill rod. I will see whether Miraphone will sell me a couple of feet of what they use. Sometimes they sell me raw materials that I have trouble sourcing here in the US. Until then, I will give the 303 SS a shot first. (If you do not know this alloy offhand, to prevent you from having to look it up, it is essentially 304 with some added sulfur to make it very machinable.

303 stainless is composed of 17% Chromium, 8% nickel, and 0.15% Sulfur.

This makes it brazable by mere mortals using air-acetylene (rather than oxy-acetylene). I considered 36 SS but I think it is a lot harder to braze. So 303/304 is not as tough or as corrosion resistant as 216, but I can work with it using the tools I already have. I can bend (with great effort) my 5mm NS rod by hand if it is about 12" long. (I can bend the 3.5mm stuff pretty easily if it is only 6" or so, by comparison.) I cannot bend the 303 SS at all in the 8" lengths I have; I cannot even flex it much. I see that as a good indication that my lever will be much improved using this material and size. Being that is supposedly very machinable I am hoping to be able to center drill a 20mm length to make a hinge tube.

Will the cheap, Chinese drill press and cheap Chinese drills be up to the task? Tune in tomorrow to find out!

EDIT: Looks like 500 RPM on the press with a very light touch (like .004" per rev feed rate, but I have to use my "eyecrometer" and "feel" to get that). I was told to watch out for a dark red heat color to the chips to gauge my feed rate, but not to "peck", or the SS will work harden and break the drill bit. I also need a better drill bit. Heading over to McMaster-Carr and Grainger to see what I can find.