The Great Kurath Re-Tubing

[the elephant]

[bloke]

(In truth, shunning them is just my excuse to toss my clothes on the floor.)

[the elephant]

I mocked up the replacement 5th valve and the new 6th valve this evening.

So far all the clearances work. I can access all the screws for both valves from both sides and there is adequate clearance to remove both rotors from the casings.

Tomorrow I plan to screw the piston set back to the bugle and set the 6th assembly onto the "exit" knuckle of the 4th piston to check clearances between the 6th casing/slide and the piston casings, 5th slide, and top bow. Once I have it figured out I will mark how the 6th has to be "clocked" and then solder it in place.
Then the 5th valve and slide can go back onto the horn. After that, I have to alter the new stop arm to work with the extant linkage.

Once the 5th is hooked up to the thumb ring I will lock the 6th valve and tape over the two knuckles. (It does not leak, but I don't want any sort of trash to get into the rotor assembly.)

Then I can alter the MTS as needed and button it all back up.

I have a gig on this tuba on Friday, so I need to get it back up and running soon. Once the gig is over I don't need an F tuba for anything for a few weeks, so I can then figure out how to mount my pair of finger paddles to the horn. Then I need to link to the existing system for the 5th so that I can use RT or L1 for that valve.

Once all that has been fixed I can focus on how to escape the corner into which I have painted myself with the 6th linkage. I think there may be a few pillow blocks (as in some old truck steering systems) and it may be in three pieces with Minibal links between them.

I'll figure it out. It will work great. But it may be expensive.

Pfffffttttt… whatever. ($1 to Dale Phelps.)
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6th — The valve has plenty of room to drop out, and there is a lot of room to adjust the set screw.

5th — This is where it has always lived, so clearances have not changed at all. However, it is now one inch farther away from the lever, so I will have to make a new linkage arm to connect them.


6th — The valve and slide seem to fit nicely, and you can tell by the brace that connects to the top bow (hanging down on the far right) that there will be enough space for the slide inside the frame of the bugle. Also, there is adequate room for drivers to remove the cork plate, stop arm, and Minibal link. The valve stem can be hammered on to remove the rotor from the casing.

5th — As stated in the other photo, this is where this rotor has lived its entire life, so no clearance issues, just the fact that it is a full inch farther from the thumb lever at the other end of the valve section, so a new linkage will have to be built. My new slide parts look much nicer than what was on there, and they fit this valve better than the slightly smaller Kurath tubing.


The first two pics were with the valves set at a slightly different angle that I ended up changing a few degrees. Here is the later setting. I won't know how the 6th has to be clocked for certain until the bugle is installed to the valve section so I can see 100% in all planes how it will fit. That will happen tomorrow, so likely all this has been "tuba mock-up self-abuse" of sorts. but hey, it was entertaining, at least. I'll know more tomorrow. Anyway, this slight rotation of the 6th valve unit looks a bit better in all regards.

[bloke]

I apologize for (once again) taking your thread down a side road and around a bend, but...

This is a somewhat popular design - both built in Germany, as well as copied in China.

Due to the mouthpipe config', it has occurred to me that this design - in particular - COULD possibly be reorganized as a classic (ie. simple) 4+2 set-up without too much sturm und drang:

[the elephant]

[the elephant]

My 5th/6th valve section is now fully assembled, but for these photos is only press-fit to the horn. (I'll install it all tomorrow.) Once it is on and braced up I can then remove and trim the MTS to deduct the amount added by the valve and the amount I wanted to remove anyway. After that, I need to make the new linkage for 5th and lock 6th in place so I can use this tuba on my Friday gig.

Once everything is fully dialed in I will take it all apart and work out any little bugs and then assemble it very neatly.

I am *quite* pleased with this new 5th/6th valve section.



NOTE that no Kurath/Nirschl parts were retained for this. Everything in this assembly is new material.

I was unable (after *many* tries) to correctly align these two slides. One of the knuckles is a little crooked. Nice. So what *is* aligned properly is the axis through the MTS up into the 4th piston port. It is aligned well enough that I can rotate this assembly between the MTS and pistons and the MTS stays in alignment and does not bind up. The 5th valve cants two degrees one way and the 6th cants back the same amount. Whatever. I'll accept that at this point in the game.














Slides in…


Slides out… ("Wax on; wax off.")


This assembly is Ginger Approved.

[the elephant]

TALES CALCULATED TO DRIVE YOU MAD
HOME SHOP EDITION #643

Today I lost an important small part. I looked high and low for it for about two hours. I even searched the bag of my shop vacuum for half an hour, sifting through the entire contents. The only thing I retrieved from that vacuum was the certain knowledge that I need to empty my vacuum.

I was boring out some detachable brace parts to make my new brace feet and rod stock compatible with the detachable brace sockets I want to use for this build. I had the threaded bases screwed into the threaded barrels that ride on the brace rod to keep all these bits together.

While drilling out my thick brass tubing to fit over the rods (to be cut into short keeper discs) I unscrewed all the barrels and the threaded bases from one another, because once the tube was drilled out I would have to also drill out the barrels. Lots of details.

Somewhere between the act of unscrewing these bits and then drilling out the barrels one of the threaded bases went missing.

So the above-mentioned search began. And after the two hours, I had become so agitated that I decided that it was in the shop *somewhere* and that I needed to get back to work if only to decompress a bit.

So back to the bench motor I went, this time to slice the brass tube into eight of the earlier-mentioned keeper discs.
As is the norm for small, split-phase motors set up to be used in a musical instrument repair shop, my spindle is hollow. This is a great feature when straightening long rods that have become bowed, or to more easily work with long rod stock.
I was holding the end of a rod inside the rotating brass tube as I held the jeweler's saw in place to cut the tube so as to catch the disc once it was parted from the rest of the tube. At some point, I decided to slide the rod farther into the spindle. It went in about two inches and thunked up against something. I tried several times and gave up, just wanting to finish cutting off the eight discs.

When I finished I opened up the chuck all the way to look inside it…

… and there was the missing part!

I had forgotten to unscrew one pair of the set of parts before drilling out the barrels, so one barrel went into the chuck with the threaded base installed. The directional force applied by the rotating motor unscrewed the base and allowed it to fall into the cavity at the rear of the chuck. The threads were slightly damaged, but I was able to rechase them and save the part. And save about $20 for a new part and FedEx charges.

I hope this afternoon's session back there goes a little better, heh, heh…

Anyway, having three types of detachable braces that look nothing at all alike has bugged me for some time. This was the first horn I had done this work to, and it was *okay*, but some of the brace types work better than others. After finishing the Holton 345 I decided what I liked and disliked about my two tubas with removable valve sections. I decided to "fix the mess" on the Kurath when I was finally in a position to do so. I have finally pieced together eight complete sets of parts to replace the seven oddball braces and add one when I fabricate the new 4th slide circuit.

Everything fits and looks great assembled. I am stoked. I just need to not lose any more parts or I am likely to blow a gasket.

[prairieboy1]

A great story for this afternoon! Glad you found the part. Keep posting text and pictures!!

[bloke]

Podophilia aside, I've NEVER EVER lost ANY little part off of ANY instruments EVER.

[the elephant]

[nc_amateur_euph]

If you fabricate about that, you'll fabricate about anything.

[the elephant]

My battery is about to die, so this will be very short. I installed the 5th/6th valve section to the tuba and did some testing. I decided how much to shorten the two slides, took it off, tore it apart, and started trimming. It was cold and windy, so lots of sloppy solder and heat blooming due to excessive heat to keep the work warm (if not screaming hot). I have it all back together, but I had to start very late, so I was out there in the dark and stopped before this step was complete. I have a LOT of cleanup to do. I will work on that tomorrow. I have a gig out of town all morning, so I will likely have this installed at the end of Saturday. I have another gig on Sunday, so probably no work then. I get to play my 186 in quintet tomorrow, which will be (not) fun. I have dyslexia and have a lot of trouble doing the same folder of music on both horns. I never do this, so my chops for it are weak.

Whatever. Here is the shortened section. It was FANTASTIC having a low B and A that are now spot on in tune. The *only* pitch issue this tuba has now seems to be the sharp second space C.

Oh, well…

[the elephant]

After I can get plugged in I will explain why all the seemingly unneeded work was done. It was… needed…

[bloke]

If you fabricate about that, you'll fabricate about anything.

clever pun

[the elephant]

On the fly, I tried a quick redesign of the 5th loop. For whatever reason, my 2-D brain does not translate all its ideas into 3-D sometimes. I took everything apart, cut new parts. It all fit together beautifully.

Then I remembered the 15º offset of the valve from the centerline of the pistons needed to allow the bottom valve caps to be fully accessible for repair work. My first layout had a slide loop that could be rotated until the exact angle was found, then soldered in place. It was quite easy to get stuff set up nicely this way.

The new way made that impossible and had the slide sticking out into my gut.

No bueno.

So after hours of work, I shortened up some parts and slapped the assembly back in its previous configuration.

<sigh>

The long and the short of it is that the new, non-leaky 5th did not make much of a difference. It is better overall, but the one, niggling characteristic in the low Bb remains unchanged. The new 6th valve is a fantastic addition that in just a few mo=inutes of farting around rotating the two valves with my fingers (no linkages, yet…) showed me how much easier the low register will be once this is all back together.

Goodnight!

[bloke]

' yet another snooty sissy - who thinks he's better than everyone else, because he acts as if he knows how to mash six buttons and play the tuba...

You are going to love the 5-6-3-4 low G, which will be spot-on, as well as the 6-2-3-4 G♯. Those pitches - on a tuba that's only 12-feet long - are easily heard in-tune/out-of-tune by *patrons, and it's so much easier to play those pitches spot-on (particularly at extreme softs/louds) with just the right amount of tubing.

You may well also discover some nice C♯ work-arounds (ex: 6-1-2 may be superior - in some octave - to 2-3, etc.) as well as (??) other uses...
...and you already know all of this, but some reading this may not have thought about these things.
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*who - via technology, and nearly always being presented with 'well-tuned' music on their media - are...whether-or-not-they-themselves know it...ALSO more acutely aware of tuning - vs. decades ago - as are many more musicians.

[the elephant]

I decided to punish myself by spending two hours outside in the wet, cold slop (39º F) in a lousy teeshirt, sweat pants, and house slippers. I know: that's pretty stupid. Well, no one has ever accused me of being anything other than that.

Anyway, I finished the 5th/6th valve section today.

As in DONE.

I will install it tomorrow. I will use this horn to play Brahms 2 all week. I will try to have a 6th linkage sorted by the concert to allow me to access the wonderful low A and B I will now have at my fingertips. (Literally.)

I also decided to assemble the two 4th slides, which was what I was doing outside for most of the time, actually. For now, they will be installed as shown in the photo, matching the current Kurath slide layout. However, when I get around to setting up my new 4th circuit the long legs will be on one slide and the two shorties will go on the other. The short one will be my lower slide and the long one will go up top so I have something with usable adjustability (when needed, which is a rare event on this tuba).

I will also take time to mention that I shortened the internal spacer in the 5th slide loop — because I *completely* forgot to do that. So I had to break out all the tools needed to cut and finish a tube end before I could finally pack up and shut it down for the day.

D'OH!

I buffed off the worst of the mess on the valve section and then hand-polished everything to even the appearance out a bit.






I like this shot. I don't know why. I shared it just because it makes me smile.


I buffed off the crap on the inner slides, but only lightly. They still have a lot of light scratch marks on them. They still have to be lapped to the outer tubes as they have that mild, never-lapped grittiness that I hate. They fit quite well, so the lapping only has to take down the tiny rough spots from the drawing process. Then they will be pretty nice slides.

[The Big Ben]

Nice piece of work! Shiny and clean!

[the elephant]

Well, I have decided to take the 186 to play Brahms this week to take pressure off of me to get this done before I am ready. I need more time to work out the levers and do not want some kludge on my horn just to play such a small part in the orchestra.

I have a few more F tuba things coming up to test it out.

So I will keep working and will take my time to make sure I am happy with it. I hate going back in to fix stuff that I knew when I installed them would not work out long-term for me.

With that in mind, I may just take another day off from this so I can work up the part for rehearsal tonight.

I also need to purchase an old school desk off of craigslist so I can practice my nuclear attack drills as we learned them in kindergarten…



Maybe I will work on the horn today. Probably not. Adios for now.

[bloke]

186 will work well for that symphony.
As that symphony gets programmed quite *often, I use an instrument with a virtually identical bell - compared to 186, but just with less overall length.

Perhaps I get too much into the details, but a fourth valve D (beaucoup de tube cylindrique) will offer a little bit of extra grit on the last note of the symphony, which I think will be good.

bloke “Really good last notes are important.“
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*me: five months ago was the most recent: horrible toothache, inadequate pain drugs, and barely over the big c