B&S tuba lyre box screw size?

[MiBrassFS]

I’ve tried the few lyre screws I have on hand and struck out.

Anyone happen to know what screw size is used for a B&S tuba lyre box?

Anyone know a source for purchase? A silver one would be extra dandy!

Thanks for any help.

[bloke]

Any chance it's just 3 mm? (I don't know of any 3 mm thumb screws that you can just buy from Battle Creek or Elkhorn...)

https://www.ebay.com/itm/316008436741

[MiBrassFS]

Well, oddly enough, it turns out to be an M4 X 0.8 tpm.

Nope, not 0.7…

[bloke]

Nearly a proprietary thread.

... but you realize that what you are defining is only within a couple of thousandths - both in diameter and turns per inch - of a super-common SAE 8-32 thread, do you not? Being brass, I can't imagine having much difficulty screwing an 8-32 screw into your nearly proprietary M4 X .8 female threads.

European threads on musical instruments have not always been metric.

[MiBrassFS]

I did try a couple of different 8-32’s. (I thought I’d try the finger button trick…) They wouldn’t even come close to starting. They’re all right at that 4.2-ish mm diameter which is just a bit too much. (Darn German precision…) Probably the best bet would be to run an 8-32 tap through. Of course, which I don’t have right now! (Thank you, brittle, soft, Chinese tools and fasteners…) If I can’t score the right euro-screw (heh, heh…), next time I buy taps and dies, I figure that’s what I’ll do. But I really prefer the right one! Because, you know, it’s the right one! “Besson” also uses this size (since 2004), so… that’s really no help, because “parts…”

[bloke]

I'm not going to get into any more specifics, because we (me: raising my hand and admitting to such) tend to become argumentative here just to show others that we can make a point - and then we end up not making a point... but when we dig deep enough into our old papers and into the internet, people who know a whole lot more about machining and history of machining than we do show us that there are (or were) different interpretations of the same thread sizes.

[bloke]

I'm not going to get into any more specifics, because we (me: raising my hand and admitting to such) tend to become argumentative here just to show others that we can make a point - and then we end up not making a point... but when we dig deep enough into our old papers and into the internet, people who know a whole lot more about machining and history of machining than we do show us that there are (or were) different interpretations/interpolations of the same thread sizes.

[MiBrassFS]

I really do appreciate the input! And, yeah, I see those internet posts saying this and that. Experts all, but no interpretation was necessary. I physically tried a bunch of lyre screws (someone lent me a bag of ’em - friendly band directors…) that included several 8-32’s and on this lyre box they were a no-go. None of them would even come close to starting. That 0.2 mm apparently does make a difference. Couldn’t shove them in there. I borrowed a screw off of another B&S/VMI tuba and it was a perfect fit. Measured it up, 4 mm X 0.8 tpm.

[bloke]

I really do appreciate the input! And, yeah, I see those internet posts saying this and that. Experts all, but no interpretation was necessary. I physically tried a bunch of lyre screws (someone lent me a bag of ’em - friendly band directors…) that included several 8-32’s and on this lyre box they were a no-go. None of them would even come close to starting. That 0.2 mm apparently does make a difference. Couldn’t shove them in there. I borrowed a screw off of another B&S/VMI tuba and it was a perfect fit. Measured it up, 4 mm X 0.8 tpm.

It seems obvious to me that they didn't outsource this stuff, and made their own. These days, we all have read about the specialization that has occurred in Europe whereby there's a bell spinner here, there's a valve set maker there, there's a small parts maker over there, and so on...
...anyway (joke) I'm glad you're able once again to take your B&S tuba to soccer games, and play all those wonderful European marches that they love to hear whilst the action is occurring on field.

[MiBrassFS]

Not until I get my own M4 x friggin’ 0.8 tpm screw!!!

Those cottage industry specialists are part of the high quality charm, right!?

Well, they actually are, to me.

[peterbas]

.

[bloke]

As you're determined to not tap out that thread in the lyre box, have you found any screws of that goofy thread that you can buy? Of course you can silver braze the threads of the screw onto some foreign coin made of nickel (perhaps roughly the size of an American dime) that has knurling around the edges, and just grind, file, sand, and buff the top side down nice and smooth, and end up with a pretty convincing Euro-ish lookin' lyre screw.

Maybe you have some local machinist buddy who wouldn't mind running that thread down a piece of nickel rod or brass rod...(??)... and then you could do as I suggested above, so is to not over-stress the favor...(??)

Wait... you own a lathe, yes?

[peterbas]

.

[the elephant]

This proprietary (or nearly so) stuff is bunk. The cork plate screws on Miraphone valves are (and always have been) M2.6x.45. Yes, you can source a tap and a die for this in the US, and yes, you can source these screws, but good luck. It took a botched order from Miraphone (where they forgot to drill and tap these two holes — WHOOPSIE!) for me to find this information out. Eva was embarrassed that they had omitted this step and sent me a packet of drills and taps to ensure the holes were going to match the screws I had purchased. I eventually located these in the US, too, but it took some time. I have a lathe now. It has all the gears needed for screw cutting. It does NOT contain gearing that allows for M2.6x.45 screws to be cut. AND IT IS A FREAKING GERMAN LATHE! Why do they spec stuff like this? I heard that Miraphone's weird sizes for things are simply the tradition of necessity, that the tooling they could get their hands on when the formed their cooperative venture was a mixture of really old (worn?) Czech stuff they had brought with them, some pre-war German stuff, and some leftover US stuff from the occupation forces after the war.

Perhaps.

But why stick with such weird sizes after the company was up and running and turning a profit? Maybe the "tradition" was more one of, "If it works why change it?"

M2.6x.45

[bloke]

This proprietary (or nearly so) stuff is bunk. The cork plate screws on Miraphone valves are (and always have been) M2.6x.45. Yes, you can source a tap and a die for this in the US, and yes, you can source these screws, but good luck. It took a botched order from Miraphone (where they forgot to drill and tap these two holes — WHOOPSIE!) for me to find this information out. Eva was embarrassed that they had omitted this step and sent me a packet of drills and taps to ensure the holes were going to match the screws I had purchased. I eventually located these in the US, too, but it took some time. I have a lathe now. It has all the gears needed for screw cutting. It does NOT contain gearing that allows for M2.6x.45 screws to be cut. AND IT IS A FREAKING GERMAN LATHE! Why do they spec stuff like this? I heard that Miraphone's weird sizes for things are simply the tradition of necessity, that the tooling they could get their hands on when the formed their cooperative venture was a mixture of really old (worn?) Czech stuff they had brought with them, some pre-war German stuff, and some leftover US stuff from the occupation forces after the war.

Perhaps.

But why stick with such weird sizes after the company was up and running and turning a profit? Maybe the "tradition" was more one of, "If it works why change it?"

M2.6x.45

I dunno if you looked at my "krantz-plant" 186 slick-out thread (lacquer, and the whole nine yards...sold to a Catholic school, whereby the band director is a 186-o-phile)...
The carriage rod was the same 3mm size, but - back then - the knurled nuts and threads at the end were that M2.6 size...
I was already ordering a bunch of Mira-stuff, so Christian sent me (they didn't have to custom make 'em...still have 'em) a couple of nuts that fit that size...less trouble than swapping out the carriage rod...and - yeah - cheap enough. Even though it was a VERY early 60's tuba, the carriage (SUPER heavy duty - as you know...nearly "armored" gauge) was still straight, as was the carriage rod.

bloke "Y'all google 'Löwenherz thread'." ...See...?? I'm not as ignunt as (even) I thought I was...

me: Me an' my buddy KNOW EVERYTHING...Just ask ANYTHING...
you: What is the common name for the volcanic glass formed from the rapid cooling of lava without crystal growth?"
me: uh...That's one of 'em that my BUDDY knows.

[the elephant]

Me: Obsidian

[bloke]

Me: Obsidian

Hey, buddy!

btw...
Did you see THIS sh!t?

https://x.com/SaveJxn/status/1874860905407918562

[MiBrassFS]

This proprietary (or nearly so) stuff is bunk.
…
M2.6x.45

I’m here to tell ya, that’s the truth! M4 x 0.8? Pffft.

Wait... you own a lathe, yes?

Ding, ding, ding! Bloke wins a nickel lyre screw! Although, It’ll probably only fit CC toobahs… So…

Dawkes has them and Thomann, too. There’s no fun in that at this point. Ordering just a single screw and paying to ship it? Nope.

Do the work? Sure did… Then have the fun.

[bloke]

Where do you plan to march with this instrument?

[MiBrassFS]

Where do you plan to march with this instrument?

Homey don’t (can’t…?) march no mo’. Homey just has lyre screw OCD. Missing lyre screws look like bullet holes to him…