TromboneChat

I am getting more and more into the numbers game of mouthpieces. Until now I only went by feel, but now I am getting really curious about the numbers. Call me crazy, you wouldn't be the first. Or the last...

Every manufacturer measures his mouthpieces differently, that makes it hard to compare mouthpieces based on the dimensions a manufacturer gives. So I'd like to measure some stuff myself. That's easy to do for a backbore, but what do you use to measure an inner rim diameter? Or a cup depth?

Of course, you could also use a caliper to measure the inner rim diameter. But then, where on the "curve" of the rim do you measure?

I know there are some special mouthpiece measuring tools for that out there. Are they worth it? Any experiences with those?

Assuming you're not going into industrial 3D scanning...

As someone with a reasonable amount of experience measuring historic musical instruments, anything involving casual hand measurements taken on curves mostly relies on having developed your eye/feel so that your process is consistent - so the comparative value of your own measurements is pretty high, even if someone else's may differ from yours.

If you 'calibrate' your eye measuring rims that you trust, you can get a pretty good sense of a 'standard' inner point based on how the contour catches the light. If you wanted to standardize further, you'd need an inside caliper with a shelf on the jaws (as pictured here, but with a deeper horizontal shelf, and only a very shallow vertical offset on the inner jaw).

Cup depth is essentially impossible, other than by visual comparison. Of 'simple' measurements, volume presumably matters more than vertical depth alone, but what really matters is everything. You say backbore is easy, but only the cylindrical throat...

Fortunately, there's basically no point for a non-manufacturer to be worrying about high levels of accuracy here, because all the subjective/perceptive factors completely overtake the measurements. I'd say caliper by eye, with practice, should be 'indicatively reliable' to 1/100th of an inch, so that's certainly good enough for you to learn what the 'real' size of, say, a Bach rim might be

I've never seen anyone mention this, but volume might be a useful objective measurement, when coupled with your other measurements.

Many of the manufacturers, the few who are reasonably accurate, seem to measure diameter at a set depth from the top of the rim. I think that's fine for mouthpieces that have the same inner edge, but when it comes to very sharp or very round inner edges, the perception of size on the lips is very different. I prefer to make a judgement on the curve as to where the player would perceive the size to be. I measure a very sharp rim at a higher point, and a very round rim at a lower point. But the player's interpretation of size can also be affected by the diameter of the high point.

Some interesting points. Volume may be worthwhile to measure to give an overall impression on the size of the mouthpiece. Cup depth may be indirectly connected to that.

What about mouthpiece weight? I know I like heavy mouthpieces. But it's not something that's usually indicated when you buy a mouthpiece.

The rim is where it's of course really complicated to get repeatable results I think. What calipers do you use to set the depth where you measure a rim every time at the same depth? Any tools for that?

Weight can be funny. You may find a Conn mouthpiece to be the same weight as a Bach, but the weight is distributed differently.

Timothy42 had suggested making molds of the cups of the mouthpieces as a way to measure volume or some dimensions. Problem may be what to model with. Plaster of Paris might be good, but it's messy. To use clay you would need a good release compound on the mouthpiece. You can use weights to compare volumes provided you use the same material to model each mouthpiece cup.

BGuttman wrote: ↑Wed Mar 31, 2021 11:00 pm Timothy42 had suggested making molds of the cups of the mouthpieces as a way to measure volume or some dimensions. Problem may be what to model with.

Perhaps the oasis blocks florists use?

Good questions, Daniel! It's all rather subjective - even the supposedly simple measurement of cup diameter, as Doug's post attests. Cup depth is my nemesis - I take evasive action whenever anyone asks.

As Doug Elliott has said, measuring cup diameters is fraught with problems because of the shape of the bite of a mouthpiece. I have a simple method to get comparative sizes.
I have a small pile of assorted coins from different countries. These are graded in different diameters and so I can do a comparison depending on how the coins sit in the rim of the mouthpiece. I have just done a check on 4 large shank, size 4 mouthpieces and discovered that they are all slightly different; the Stomvi Comby System size 4 is fractionally larger than the Wick 4AL which is slightly larger than the Bach CORP. 4G. The Doug Elliott 102 rim is slightly smaller still.
Measuring cup depth is even more difficult and I use "the rule of thumb". I insert my thumb as deep as possible into the cup of the deepest mouthpiece and then, using my index finger, I slide that down until my finger nail meets the rim of the mouthpiece. Holding my thumb and index finger in the same position, I place my thumb into the cup of the next mouthpiece and check the difference between the rim and my finger nail. This gives a comparison between the depths of the different mouthpieces and also gives an indication of the shape of the cup, bowl shaped or funnel shaped.

The measurements are not quantifiable but are probably as accurate as the figures given by the manufacturers when comparing different brands.

Cheers

Stewbones43

On the topic of measuring mouthpiece depth, I have occasionally thought that there might be a tool that works like a pin mold - the toy that has hundreds of small metal pins that move when pressed to create a mold of your hand or face. Here is an example of what I am taking about: https://www.amazon.com/Pin-Art-Impressi ... B00V57F4K8
I don't think the toys I have seen are deep enough to measure cup depth, but a determined DIY tool maker could probably modify one of these toys to include longer pins, or make something from scratch based on the principle.

Just an idea - how about using clay, Play-Do, plaster, or something like that to make molds of the mouthpiece cups from the rim to the throat? That would make measurements at different depths easy, and you could see the difference in shapes when the molds are side by side. The same could be done of the back bores.

This company is doing some interesting things, including measuring and digitizing mouthpieces.

https://www.vennture.mp/product/mouthpiece-scan/

Taking molds of a mouthpiece cup is easy using a dentists 2 component plastic mass used to take molds of teeth. This stuff seperates fine from polished metal, and you can cut the molded interiour with a sharp knife into two halves, revieling a fine picture of the cross section.

For getting more accurate measurements of the form of the cup, you can buy assorted sets of steel balls, for bearings, and drop them one by one inside the cup, then measure the height of the upper ball perimeter to the cup rim using calipers designed to measure hole depths.

Different diameter balls will ride lower or higher in the cup, giving you a good comparision of cup size and shape between different mouthpieces.

Shims or coins of assorted size are good at comparing inner rim diameter, as pointed out above.

Kdanielsen wrote: ↑Thu Apr 01, 2021 7:28 am This company is doing some interesting things, including measuring and digitizing mouthpieces.

https://www.vennture.mp/product/mouthpiece-scan/

This is awesome, great find! Thanks for sharing this