Kurath F — Reimagined 6th Slide

[the elephant]

My approaching blindness is due to diabetes.

And yes, I use a member of magnification devices, including a large magnifying glass, a set of ancient specs I "liberated" from my bench at the music store when I left in 2004 that were made in the 1960s and that no one else wanted, and this headband with an LED lamp and snap-in lenses of varying magnifications that can be flipped up and out of the way, but that I frequently forget I own, sticking with the old-man, 1960s specs. <sigh> I'm a little stupid in that regard, I guess…

[the elephant]

I had a very happy moment of clarity as I was working yesterday.

I no longer have to make the linkage rods from that damnable stainless steel stock I had been using. The erstwhile 6th linkage was this horribly complex shame that was prone to flexing, so I used the SS because of its rigidity-to-weight ratio, and it worked well for that. But that very rigidity caused it to snap when I was making the rods, and it took a LOT of physical labor to bend them. I would bruise my palms and fingers all the time when I was prototyping these rods until I came up with one that worked. And it was costly stuff, too.

Now I can use plain, old brass or nickel silver, as the rods both can be either straight or almost so. This will be much better. I love Rube Goldberg, but I do not want to be Rube Goldberg.

Replace this mess with a straight rod? SIGN ME UP FOR THAT, BOY!

[the elephant]

I am sick today, so I only did a little work. I reassembled the pistons to the bugle and installed everything that affects the alignment at the MTS, so I even installed the 5th/6th levers as the bracket serves as the bell-to-1st slide brace.

In short, everything still fits; no home invader snuck in and stepped on any of these bits when I was sleeping.

Nice to know, I suppose…

Oddly, though this started as an unhappy compromise with the "wrong" valve and a cobbled-together 6th circuit, I am VERY HAPPY with everything. It all lines up better than the 5th/6th section that I was originally using.

[SECRET KNOWLEDGE: When you expand or shrink the ends of tubes to accept joining with other tubes that are not the exact, same size, you can do some very interesting things. HOWEVER — when you do this to a valve knuckle or anything VERY CLOSE TO A CURVE you run the risk of idling what I did with this tuba the first time out. Because tight curves net you metal that is far thicker on the inside face and far thinner on the outside face (as compared with an unbent section of the same tube) when you hammer a form onto or inside the end to shrink or stretch it the reshaping will be ever so slightly off center, toward the outside of the curve, as that thinner metal will give sooner than the thicker stuff. So if you want to use a very slightly larger 2nd rotor crook, you have to slightly expand the knuckles on a rotary case. AND THE EXPANSION WILL SPREAD THE TWO TUBES APART ABOUT .25 MM — PREVENTING THE SLIDE FROM BEING ALIGNED. If you expand the two knuckles ends enough to properly use the larger tubes you will make the center points of the two ports a quarter to a half of a mm wider than the centers of the crook. This drove me crazy with the 2nd slide of the Holton when I bumped the tubing up from 19 mm to 19.5 mm. The factory crook would no longer work; I had to switch to the Miraphone crook, and that required some adjustment, too.

So, you may ask, what is my point concerning this tuba…?

The two old 5th (mine, not the Swiss one) was simply a stock Miraphone valve of that specific bore. That was how I was going to run with this back then: same setup (five valves in one hand). THEN I screwed with my world by deciding to add a 6th valve because I had what I needed here at hand.

After my experience stretching the exit port of the Miraphone rotor case to fit the now-larger small side of the MTS (this tuba had some major taper issues — I corrected a lot of stuff and it plays better now) and wanting my 6th valve to have several things oriented correctly from the factory rather than it being obvious that I made this crap in my carport at home, I decided to order a custom valve from the good folks in Bavaria. My previous custom orders all had been well executed and affordable… so why not treat myself?

The second time around I ordered BOTH valves custom, so the exit ports being larger did not affect the final alignment between the piston block exit port and the small side of the MTS. So by spending the extra $$$ on the two valves, I ensured that this small "stack" was very straight from end to end. Et voila! The MTS works better than it ever has. Unintended benefits: I love them.

And I learned a valuable lesson was learned regarding tubing expansion.

I soldered the two rotor cases together. The offset was not as much as I had feared. I was hoping for a nice, neat-looking setup whereby the two rotors were in line exactly, but this couldn't be (for several reasons, the main one being how I rerouted the 5th slide). The offset is about 10º which is fine. It does not look bad at all on the horn. The main issue was the "sight picture" of the slide tubes possibly blocking access to the bottom valve caps. The 10º offset along with an additional 10º rotation from the piston valve plane gives me a very clear path to the caps so that work can be done from the bottom (like polishing "reamer" insertion and such).

Assembled as in the photos, the MTS has an easy, even pull, tight enough to stay where I set it, but in no way binding in the pull.

I'm pleased as punch with the outcome of this work! The tuba will be a good bit better than it was before the addition of the 6th valve, and the 6th valve added some serious utility to the low end of the horn.

I think I need to give myself a pay raise…

5th at maximum pull to check clearance with the 4th valve "hoop" behind it…


Access to the bottom piston caps is excellent…






5th slide is back in; 6th is, too, but I have not yet cut the slide itself, thinking I will shorten it against the tuner, a bit at a time. I think the other legs are where I'll end up. I think this layout looks decent. I just wish the more gentle curved elbows I have had worked out, but alas, it was not to be. Boo-hoo…









Here is the dreaded offset. I do not hate it like I thought I would. The offset in the previous setup was more like 45º and made the whole thing look non-factory. This setup, on the tuba, looks like it goes there. (Yes, this is soldered.)


All this sloppy solder work is due to my vision problems: I can't see well enough to wipe it with my oiled Q-tips. What I can see I can clean. I could not see this mess, sadly. I will take care of it tomorrow before soldering the rotor section back to the pistons and bracing it all up.

[the elephant]

Since I was just asked, here is an old photo showing how these valves are actuated. I used two Swiss coins minted the same year as the tuba for my platens (they are made of nickel silver, happily, and brazed to the lever arms without issue). The rack is located behind the 1st slide. In the pic, the 1st slide is to the left, the bell to the right, and the leadpipe is on the lower right. This hand position is only slightly different from what I have used for years on this tuba, and it works quite well for the valves. Other than the cap head bolts and thumb screws (on the lever axle) everything in this rack was scratch-built here in my lovely carport.

[the elephant]

It's installed. The soldering is messy but will clean up easily enough. One unintended outcome of rerouting the fifth slide and giving it a lot more pull is that it may capture my hand or require me to alter my hand position if it has to be pulled any more than in the photo, as you can see. I need to play it for a while to see what I want to do—if anything. This may be a non-issue.

Alignment at the MTS is perfect. There are no leaks to be gone over. I want one more brace. I might want to rotate the whole thing back closer to being in line with the pistons as the offset did not need to be as much as I used. I do not know why I did not see this BEFORE I soldered it all together. (I cut the post for my brace a bit too long, which rotated the whole assembly from the plane of the piston set a bit more than I had intended.)

[arpthark]

Can you remind us what the ring on the 4th valve tubing is for? That's not a stock strap ring, is it?

[the elephant]

There are two, a thumb ring and a pinky ring.

[the elephant]

Due to my incredible mathematical idiocy, I hacked the 2nd slide thinking it was solving an irritating issue… and it did… and that introduced a passel of other issues that I did not notice at the time I did the work, so much later when I discovered the issues I suspected it was due to my new and rather different leadpipe having shifted some pitches around.

But no. Two months ago I discovered an undetected leak between the rotor and piston sections.

DERP…

Last spring everything with this tuba got quite weird as I prepped for my run of quintet recitals as well as a solo recital. As I said: I initially believed it was my new leadpipe. I chased the various issues with mouthpieces, drone pitches, tuners, and a little bit of panic. I worked out all the issues to my satisfaction, but the tuba had become a lot of work to play well.

It turns out that I had somehow missed a sizable leak. I leak-test every tube connection I solder together but — obviously — I missed this one.

Now that the leak has been fixed I was able to address a lot of the new pitch issues, and most of them involved the funky-short 2nd slide. I figured out that the leak had caused a lot of pitch havoc and mayhem, and now (being leak-free) this slide needed to be pulled back out to its normal length… just beyond its end.

Great…

So my next task was to splice in patch tubes to lengthen the inner slide legs. Since I am out of those two sizes of tubing right now and this works well, the spliced-in sections will stay for now. (I'll make a new set of inner/outer legs this summer.)

What I have done looks like something Ricky and Bubbles would have done in Trailer Park Boys. It is ugly AF and badly needs to be cleaned up on the buffer.

Fixing the leak and returning the inner legs of the 2nd slide to the arithmetically correct length set things back aright…

… and now I think I may sell the Adams.

The 6th valve enhances the low register quite a bit, adding some undeniable utility to this beastie. And I am not doing ANY work to this lovely Adams.

I still have a lot of work left to do on this instrument; rigging the rotors to the levers is next on the list. That will allow me to start using it at work again.

[prairieboy1]

Thank you for once again posting photographs and text! It is greatly appreciated!

[TheBerlinerTuba]

Excellent work, bravo

[the elephant]

Well, I lack tools that would have made this a heckuva lot easier, faster, and nicer, but I have what I have, and I had little time and low supplies from which to draw. All this was done with a Dremel tool. Cutting, shaping, drilling, buffing, all on a Dremel. The tapping was done using a cheap hand-tap wrench. The silver soldering was rushed, again: tight schedule today. So the coins are a little crooked but are crooked to the same angle and amount. CRAP! But unless I want to do this again they stay where they lay.

These levers correct several little details I got wrong (all guesswork, if you remember). Though they worked, I disliked several aspects and decided to try again this time.

Maybe I will do this again. Probably not.

Linkage arms tomorrow.

The base of the bracket, the three tabs, and the lever arm are cut from the same 1/8" nickel silver plate. The hinge tube, steel hinge rod, steel thumb nuts, and the two 1989 Swiss Franc coins are not, of course…


I was in such a hurry I failed to drop these in the vinegar "pickle" to etch off the "glass" from the flux. I have to sand the resulting mess off and rebuff the parts, but otherwise, these came out pretty well.

[bloke]

Every time I've put coins on instruments I put them on pre-existing spatulas, which meant that I could lead solder them in place and it's much easier to line them up straight with lead solder, of course. I REALLY like your idea of silver brazing them directly to the arms, because it reduces weight, and reducing weight defines that the spring tension doesn't have to be as taut. (Springs that are unnecessarily strong are a feature that I personally find annoying.)

I've thought about putting some of the same Deutsche marks on my big Miraphone rotary tuba that I put on the 186 (that Bill purchased from me). I love the eagles on the obverse, and the diameter is a perfect fit for Miraphone spatulas. The thing is that now that I'm so neurotic and fixated about the weight of mechanisms, I'd probably want to put each of the spatulas on a milling machine and take that circular end area down by about half the thickness of those coins, and then put the fronts of those coins on a milling machine and take them down by 50% as well, so the eagles would be flush with the tops of the factory spatulas, and that's a bunch of mess/trouble, so no.

...but what I might (??) be more likely to do would be to ask Christian for four replacement levers (sans the spatulas), and do them just as you did yours. I know you can imagine just how that would look with four of those, and what it would accomplish would be a very old world look, even though it wouldn't have the S arms.

[the elephant]

Very mild COVID. I'm having to miss four MSO or MSO BQ performances this week. Thankfully, I'm not getting docked from my salary.

The first few days will be the worst, and so far I am mostly experiencing a loss of my senses of smell and taste. (Last February when I had COVID I thought I was going to freaking die. This time at bat is much less horrid.)

I probably will not be getting much work done on this tuba for a day or two, depending on how I feel. Certainly not today.

Blargh…

[York-aholic]

Feel better, that's an order/command!

[the elephant]

COVID Labor Therapy

Richard Simmons would have been so proud of me, sweating to the oldies as I was all afternoon… I had my Motown playlist blaring away in the shop, probably causing some feline consternation, but that's too bad…

I did a lot of piddly stuff to while away the time, without actually breaking a sweat. Chiefly, I gathered all the sundry junk I had at hand to create a linkage system to connect the levers and the stop arms. It turned out that I needed four of everything and had three. (Figures.) After crawling around in the bowels of my junk parts boxes I *finally* found four of everything I needed, as well as matching lengths of rot that are longer than a foot. (It is sold by the foot, so this caused me a lot of heartburn, but I did get something adequate.) The issue is that this is a system that I abandoned when I boarded the Minibal bus back in 2018. I did not dislike this set of parts, and had never once experienced any issues with them, and — to be bluntly honest here — I like them better than Minibal rod ends in certain situations, and it happens that this is one of them.

I chose to use a 13" chunk of drill rod, 11" of 4-40 all-thread, two brass tubing (cut to fit) that snugly fits over these steel rods, and some RC ball and socket joints that I started using back around 1995. This system just works, and it is very stiff and lightweight. These being so long, the springs were having some trouble giving a quick action, so these links that weigh less than half of what the old ones weighed ought to give me a lot more snap without having to jack up the spring rate of my levers. (Another bonus: I no longer have to source stouter springs. Woot!)

These are super simple, unlike the wild Rube Goldberg-esque creations I fussed over before. Simpler is better. Lighter is better. Cheaper is better. (Oh yeah — these are super inexpensive compared to the Minibal/stainless rod links I made two years ago.)

I had to stop because my wife wanted me to take my insulin and eat, and — wow — somehow my screwing around in the shop for a few minutes turned into four hours…

Tomorrow, if I feel well enough, I will finish the system by fitting the brass tubing (cut to length, bevel one end to a specific angle, superglue the sockets to the steel rods to prevent shifting over time, install the springs to the levers, and go practice my tuba for a couple of hours!

5th is still just the 4-40 all-thread, which is flexi and weak. The brass tubing on the 5th linkage adds a ton of strength/rigidity without any real addition of weight. (Each tube weighs just a few grams.)


The bends at the sockets are there, but they have rotated inwards, so you can't see them; they are not glued to the rods yet. The bend allows the socket to swing around the stem without coming into contact with it, so no clicking.




Nice, straight shots from one point to the other. Much better than what I used to have. I wish I had just decided to do things this way from the get-go. I would have wasted a LOT less time and money. But hey: EXPERIENCE. (Heh, heh, I don't need any friggin' experience. I need CHEAP!)


No Minibal links! Just simple, snap-on ball and sockets sets of superior quality.

[bloke]

The Dubro links on my F tuba are now probably well over thirty years old. They are connected end to end with all-thread, which I bent when I installed that stuff. (Were I not so lazy, I might cover the all-thread with black shrink tubing, but we only care about the sound, right? ) Those links are fabulous, I bought the ones are actually adjustable, so that - when the brass ball or the plastic wears a little bit - the play can be removed. They will never click like old worn Minibal/Jinbal links will eventually click.

Good for you.

[the elephant]

The video is 8:02 and is just me reviewing what I have been working on with this tuba for the past week. The below paragraph is what I shared with this on Facebook for my well-intentioned friends who insist on telling me the world will end if I do not get my arse back to bed. Horse apples!


____________________

Yes, I have COVID but it is a very mild case, so I worked in the shop today for a while because that Shirt is both therapeutic and cathartic for me. No, I am not going out and acting as a sort of Typhoid Mary (COVID Wadey?) No, I am not stressing my system. No, I am not doing anything improper or stupid. I'm just a little spacey, but hey, I'm seated, so get over it. I am fine. I can't taste or smell anything, and I have a fever and am super tired. But other than that I'm fine. Let me work off my fever in a manner that pleases me. I cannot stay in bed for 15 hours a day. I will go insane.

[the elephant]

I lied. I feel like crap, but it is time for supper, and then it is back to bed where I will watch a movie and hopefully sleep. (I had a lot of trouble sleeping last time I had COVID-19, and it seems that this is a consistent thing for me.)

[bloke]

That contraption looks like it's going to work quite well, and it makes sense that you can operate that stuff and still move the first slide, because most of the stuff you need for the first slide doesn't involve the low range with those valves. That's pretty darn clever.

covid? yeah...sux...get better please !!!

me...with only very minor ailments (lucky)... I tend to get sick(-ish) every time I go out of town to play with one of these freeway philharmonics. I suspect NOT being around people (I don't even go to the store) very often has made it easier for various cooties to latch on to me... between the 4th and the 12th December ("xmas rush hour"), I fully expect to pick up some sort of upper respiratory crap of some type. I just hope it's not too bad.

Everybody's rooting for you. I'm sure you know that.

[bloke]

That contraption looks like it's going to work quite well, and it makes sense that you can operate that stuff and still move the first slide, because most of the stuff you need for the first slide doesn't involve the low range with those valves. That's pretty darn clever.

covid? yeah...sux...get well, please !!!

me...with only very minor ailments (luckily)... I tend to get sick(-ish) every time I go out of town to play with one of these freeway philharmonics. I suspect NOT being around people (I don't even go to the store) very often has made it easier for various cooties to latch on to me... between the 4th and the 12th December ("xmas rush hour"), I fully expect to pick up some sort of upper respiratory crap of some type. I just hope it's not too bad.

>>> Everyone's rooting for you. I'm sure you know that.