TromboneChat

Claudio wrote: ↑Sun Dec 26, 2021 1:38 pm very useful table
my Yamaha Xeno Bb/F is 78.6mm (by caliper) inner slide

Could you tell us the exact model number/letters? I don't think all the Xeno models are the same in this regard.

ithinknot wrote: ↑Wed Jan 19, 2022 3:03 am Could you tell us the exact model number/letters? I don't think all the Xeno models are the same in this regard.

YSL882O
380415

XO 1634RLT 68.3mm
Yamaha 445 79.2mm
Yamaha 448 78.5mm

This chart is a little disappointing. Measuring inside widths doesn't at all get to what people want to know, and as a mechanical engineer, it's a pointless measurement.

Still, it's what we have. If someone would like to include measurements for Getzen 3508 and 1050 (especially center to center measurements), I'd be interested in that...

hyperbolica wrote: ↑Tue Jun 14, 2022 7:55 am This chart is a little disappointing. Measuring inside widths doesn't at all get to what people want to know, and as a mechanical engineer, it's a pointless measurement.

Still, it's what we have. If someone would like to include measurements for Getzen 3508 and 1050 (especially center to center measurements), I'd be interested in that...

I am not sure what you want to know.

OneTon wrote: ↑Tue Jun 14, 2022 8:11 am I am not sure what you want to know.

The inside-to-inside measurement vs the center-to-center. Inside-to-inside measurement doesn't give a true picture of the width of the slide. The information you really need is from the inside of the bottom slide to the centerline of the top slide (center of mouthpiece). The things most people are worried about with the width of the slide are if the neckpipe will press into your neck, and the general design of the horn (wide vs narrow slide). Any figure from the manufacturer is going to be center-to-center.

For the Getzen measurement, as long as you state how it was measured, I can figure out what I need.

hyperbolica wrote: ↑Tue Jun 14, 2022 9:16 am

OneTon wrote: ↑Tue Jun 14, 2022 8:11 am I am not sure what you want to know.

For the Getzen measurement, as long as you state how it was measured, I can figure out what I need.

Exactly.

hyperbolica wrote: ↑Tue Jun 14, 2022 9:16 am Inside-to-inside measurement doesn't give a true picture of the width of the slide.

But it's easily obtainable, and it gives a perfectly good comparative picture of what's going on. (If you're equipped to accurately measure tube ODs, then you can generate center-to-center measurements to your heart's content... and the bore size discrepancy is relatively insignificant when you consider that none of the 70mm slides will be a .562", and none of the 90mms will be .485".)

hyperbolica wrote: ↑Tue Jun 14, 2022 9:16 am The things most people are worried about with the width of the slide are if the neckpipe will press into your neck, and the general design of the horn (wide vs narrow slide).

Exactly. Which is why excess precision (be it inside-to-inside or center-to-center) is largely useless here; as a mechanical engineer, you'll be well aware that the center-to-center width still doesn't tell you exactly what's going on with the neckpipe, as its proximity to your neck depends on its curvature and/or the angle of the receiver (and that's before valves get involved).

All you can get from these slide measurements is a sense of general design, for which everyone will already have a point of comparison - 'standard small bores (68-70mm) are usually fine but anything significantly smaller won't fit', or '88H (c.80mm) is too narrow but 42B (c.90mm) is ok'.

It's a non-standard measurement that requires goofing around to get even comparative information. When manufacturers list a dimension, it's c-to-c. Better to adhere to a standard than worry about people who can't take measurements.

hyperbolica wrote: ↑Tue Jun 14, 2022 11:18 am goofing around

Well, I'm sorry this has been weighing on you for the last 18 months

Serious question: where have you seen a manufacturer list a c-to-c slide width measurement? (I'm not talking about general practice in technical drawings.)

I've never seen an actual numerical value (of any standard). M/K Drawing gives center and inside widths on their replacement crooks, but I've never seen horns listed with anything other than 'wide' and 'narrow' in the few places those options exist... Shires, for example.

hyperbolica wrote: ↑Tue Jun 14, 2022 11:18 am Better to adhere to a standard than worry about people who can't take measurements.

I'm temperamentally predisposed to agree with you but, in this particular case, I think collecting a greater number of 'not hugely accurate but usably indicative' data points is of vastly greater public utility than having fewer models covered albeit with higher quality data.

ithinknot wrote: ↑Tue Jun 14, 2022 11:30 am Serious question: where have you seen a manufacturer list a c-to-c slide width measurement? (I'm not talking about general practice in technical drawings.)

It only grates on me when I look at that chart and have to figure out what kind of left-handed calculation is needed to find equivalent spacings or max width.

Where have you seen anything other than c-to-c measurement shown? I guarantee that they all have a drawing with a c-to-c dimension shown for each model slide, and I'd be surprised to see anything else.

hyperbolica wrote: ↑Tue Jun 14, 2022 11:49 am I guarantee that they all have a drawing with a c-to-c dimension shown for each model slide, and I'd be surprised to see anything else.

Of course, but they're not providing that information publicly - hence the Fisher-Price method for encouraging community participation.

(Again, the slide width alone still won't always give you what you want for 'buying without trying' confidence. If the slide measurement is borderline for you, a few degrees difference at the neckpipe/receiver is going matter a lot more.)

hyperbolica wrote: ↑Tue Jun 14, 2022 11:49 am

ithinknot wrote: ↑Tue Jun 14, 2022 11:30 am Serious question: where have you seen a manufacturer list a c-to-c slide width measurement? (I'm not talking about general practice in technical drawings.)

It only grates on me when I look at that chart and have to figure out what kind of left-handed calculation is needed to find equivalent spacings or max width.

Where have you seen anything other than c-to-c measurement shown? I guarantee that they all have a drawing with a c-to-c dimension shown for each model slide, and I'd be surprised to see anything else.

I've only seen inside to inside dimensions in any technical drawings I've ever seen, but I haven't seen the secret manufacturer drawings you're alluding to. I've only seen measurements of existing trombones. But if you were drawing up blueprints to manufacture a trombone, what use would a center-to-center dimension be? That's certainly not how you would build it. If you're drilling holes in a framework where bolts are going to be inserted, I would understand the centerline measurement, but if you're attaching tubes at their outside diameter to be a set distance apart, wouldn't you need to know the length of the brace rather than a calculated dimension to a centerline that would never be physically measured?

The cut on the end of the brace has to be concentric and equal radius with the cork barrel, which is concentric with the slide tube. The centerline is the datum. If it just touches at a tangent point, any number of things could be wrong with it. If you're calculating back to find the tangent point, that's ok, but you're calculating back from a set of concentric relationships between parts. The datum is the center. Check your GD&T tolerancing standards.

The CNC code runs off of centers. Lathes are built around the concept of center, and how much of a trombone is cut on a lathe? You have to build fixturing, where each hole is cut using a center. As a designer, the tolerance has to be run off of centers and diameters, not tangent points. A tolerance for a mating slide wants to know where the centerline is. If you're manufacturing tube, it is specified/inspected by straightness of the centerline and diameter. Imagine trying to place a slide tube inside a cork barrel without using centers. If your tubes were all rectangular, then yeah, measure to the sides.

When you manufacture a frame from pipe cut on a laser cnc, it's all centers and diameters. When you bend pipe on a cnc pipe bender, it's all centers and diameters. You can back other information out of that, but to get there, it's all centers and diameters.

If your were making tooling for manufacturing, for example a wood form for bending slide crooks or tuning slides, that form would only concern itself with the inside radius... You might bend different diameter tubing on the same form. Center-to-center would be different depending on the tube size.
I think you're trying to force current CAD concepts onto a manufacturing process that is hundreds of years old, and brass instruments are still built that way for the most part.

Many parts are made on a lathe, but the trombone is not assembled on a lathe. The braces are actually cut square. There is a socket with a flange that matches the outside circumference of the slide tube. I don't see what that has to do with any centerline.

As Doug said, crooks are bent around a form. Strictly inside diameter.

Also, if I'm say for example, making a cork barrel on a lathe, I need the inside and outside diameter measurements. I would take the center for granted, because it's a lathe. I don't understand how the center would come into play there. I don't need to measure where the center is. Placing it over the slide tube? You use some sort of a jig.

Most trombone designs predate lathes or CNC machines. I agree with the above -- the design is built into the bell mandrels and jigs. If you wanted to make Conn trombones, you need the jigs, not the measurements. To say nothing of HOW you use the jigs and mandrels.

That's me, with no real knowledge about instrument design. But yeah, talking about CNC lathes seems odd. They weren't and aren't using those.

hyperbolica wrote: ↑Tue Jun 14, 2022 2:07 pm The cut on the end of the brace has to be concentric and equal radius with the cork barrel, which is concentric with the slide tube. The centerline is the datum. If it just touches at a tangent point, any number of things could be wrong with it. If you're calculating back to find the tangent point, that's ok, but you're calculating back from a set of concentric relationships between parts. The datum is the center. Check your GD&T tolerancing standards.
...

So, having seen many of the manufacturer's blueprints... There is no GD&T on almost all the drawings. None. Zero. Zilch. Just an annotated cartoon with nominal values and assumed tolerances.

This is a build process that is still adapting to the industrial revolution, not even mid-century manufacturing.

FWIW, this 62H print does use center to center for tuning slides, tho. (BUT also note the dimension to the inside of the back bow from the valve center. Easy to pick off the valve center, not easy to pick off the center of a tapered bow). Cheers,
Andy

As one who dabbles in mechanical engineering and design for a living, I can say that centre to centre dimensions have their place.

In most machinery design and some structural applications it is the norm, particularly for features that have obvious centres eg bearings, shafts, pipe work etc.

The chart created by ithinknot is a great resource. Inside to inside measurements are an appropriate dimension for the purpose.

quoting ithinknot "All you can get from these slide measurements is a sense of general design, for which everyone will already have a point of comparison - 'standard small bores (68-70mm) are usually fine but anything significantly smaller won't fit', or '88H (c.80mm) is too narrow but 42B (c.90mm) is ok'."

Which is exactly how I use it.

Moderators : any chance it could be made into a sticky note so it is easier to find?

Thanks

Phil

elmsandr wrote: ↑Wed Jun 15, 2022 4:40 am FWIW, this 62H print does use center to center for tuning slides, tho. (BUT also note the dimension to the inside of the back bow from the valve center. Easy to pick off the valve center, not easy to pick off the center of a tapered bow).
62H Print.jpg

Cheers,
Andy

Yeah, this drawing is all centerlines with one exception. The distance from the line connecting the centers of the rotors to the tangent point of the inside of the bell crook. Crooks aren't true circular or toroidal features, so there is no real center.

GD&T started as a military standard in the 40s, but didn't really make much of an impact on general manufacturing until 90s or later, so it's not surprising that a hand drawing of a hand assembled product doesn't use that. I'd be willing to bet that a company like Yamaha uses it, though. Still, that's not the issue here, the issue is that the product, even on hand drawings, was designed referencing centerlines for distance between tubes, not tangent silhouette edges.

I'm not a trombone manufacturer. I want to comfortably hold the instrument. The distance from the bottom of the top cork barrel to the top of the bottom cork barrel is the information I need. Is it a perfect predictor? Probably not. But a centerline to centerline distance isn't any better. Unless I wanted to make an instrument myself, I wouldn't get my panties in a twist about not reading center to center.

If you wanted to fit a horn to a case, you'd need an outside to outside dimension. If you want to fit to your neck, you'd need a bottom to center dimension. And you'd have to make sure it wasn't measured at a ferrule, barrel or oversleeve. C-to-c is the same everywhere it doesn't matter where you measure it.

It's just a left handed technique to get a goofy dimension.

It doesn't interest you, but others have found it useful.

Let's leave it there.

WIth the renewed "interest" in this thread, I finally looked at the table.

I noticed that the Bach 8 was not listed... I have a NY 8 that measures 69mm.

I like it the site the way it is. I can get a quick idea of whether something will work or not. I know how it was measured. The tool or jig used to fabricate the parts typically becomes the part definition and any drawings are reference only. CAD definitions have a tolerance and that can worsen in tight bends. Find the true center of a irregular tube.

Thanks to the people that created the thread and update it.

OneTon wrote: ↑Thu Jun 16, 2022 11:49 am I like it the site the way it is. I can get a quick idea of whether something will work or not. I know how it was measured. The tool or jig used to fabricate the parts typically becomes the part definition and any drawings are reference only. CAD definitions have a tolerance and that can worsen in tight bends. Find the true center of a irregular tube.

Ha, I just noticed that after you mentioned it. All of the center to center tube measurements are marked 'ref' on that drawing.

Couple of additions:
- Benge 190 80.5mm
- Blessing B8 79mm

Does anyone have measurements for Conn 32h or Yamaha ysl356?

hyperbolica wrote: ↑Mon Aug 15, 2022 9:24 am Does anyone have measurements for Conn 32h or Yamaha ysl356?

Yes ...you

hyperbolica wrote: ↑Mon Feb 10, 2020 9:31 am Conn 32h 2.60"

356 is also on the big table - and it's the same part that's on your 350C.

There's a problem with the King 2B measurements. The King 3B is listed at 68mm, yet the King 2B is listed at 69mm which is wider. But the 2B that I owned was definitely narrower than the 3B that I currently own. I measured my 3B and can verify that listed measurement is correct. Unfortunately, I cannot verify the 2B since I sold it.

Also, I can add Bach 42 is 88.25 MM.

Oh, I see the problem. I've got one set of posts collapsed, so they don't work for find in page... And... the 350c isn't at home right now.

glenp wrote: ↑Mon Aug 15, 2022 10:22 am the 2B that I owned

Well, there's variation out there, and in any case a lot of slides are out .5mm (or worse) over their length. Some of the 2B measurements were taken by me, so I'm not too dubious about the others matching.
I've added your 42.

ithinknot wrote: ↑Mon Aug 15, 2022 10:33 am Well, there's variation out there, and in any case a lot of slides are out .5mm (or worse) over their length. Some of the 2B measurements were taken by me, so I'm not too dubious about the others matching.
I've added your 42.

Thanks.

Do you think that any of the variations actually resulted in a 2B being wider than a 3B?

glenp wrote: ↑Mon Aug 15, 2022 10:44 am

ithinknot wrote: ↑Mon Aug 15, 2022 10:33 am Well, there's variation out there, and in any case a lot of slides are out .5mm (or worse) over their length. Some of the 2B measurements were taken by me, so I'm not too dubious about the others matching.
I've added your 42.

Thanks.

Do you think that any of the variations actually resulted in a 2B being wider than a 3B?

Smaller tubes too.

Burgerbob wrote: ↑Mon Aug 15, 2022 10:46 am Smaller tubes too.

Ahh yes; wasn't thinking about that.

Does anyone have measurements for these medium bore slides:

Shires TW25(LW)
Getzen 1036

I just measured the following:

Shires QB62 (Q36 bass) - 89 mm
Shires QTW47 (Q30 large tenor) - 90 mm

Correction: Shires QTW47 (Q30 large tenor) - 90 mm

Getzen 3508 = 70mm
Holton tr159 = 89.7
King 1480 (1961) = 82.4

SwissTbone wrote: ↑Mon Jan 04, 2021 5:52 am

ithinknot wrote: ↑Mon Jan 04, 2021 5:42 am

Hopefully they're off by 1 or 2 mm

But yes, and that's why we needn't worry too much about decimal accuracy... the value of the info is comparative, rather than absolute.

Keep 'em coming!

Oh yes. Mm not cm.

As long as we're being careful about distinguishing between the symbols for centimetres and millimetres, let me remind everyone never to start a sentence with an SI symbol: Mm is a megametre! Nor to use italics or capitals (for symbols) for emphasis. Spell out the name, instead. And also to leave one space between the numerical value and the symbol.

[Sorry to sound 'picky'—I was intimately involved in the redefinition of all the SI base units not too long ago, especially the kilogram and mole. So I feel 'duty bound' to comment.]


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