Drilling out a mouthpiece throat?

[jon112780]

I just want the throat a hair larger and figured on using a drill press and some grip pliers. What's the best kind of twist bit to use for brass?

I've never drilled a mouthpiece before, any concerns about grabbing or getting to hot?

Is it easy to wreck a mouthpiece doing it myself, or should I get a repair tech to do this?

[J.Harris]

While this may not be difficult with the right tools, without them you'll probably ruin the mouthpiece. You should hold the mouthpiece in a vise. I doubt that you'd be able to sufficiently hold it with any hand held tool. If the bit grabs the mouthpiece while drilling it would likely spin it out of your grip, potentially breaking the drill bit, injuring the drilling party and gouging the mouthpiece. Also, remember that you'll be removing some of the plating when you drill it out exposing the brass which might provide an unpleasant taste when inhaling.

Any regular metal cutting drill bit should work fine for brass. Just remember that brass is soft, kind of "gummy" and does heat up quickly. Use a low rpm on the drill press (probably the slowest available) and lubricate the bit with some sort of oil before attempting. Good luck.

[joshwirt]

And you'll probably want to have a new mouthpiece ordered BEFORE you do this...

[joh_tuba]

MUCH better advice than mine given below.

I'm not a mouthpiece guy and have never enlarged a throat. Can't imagine much tangible benefit.. but again, I'm not a mouthpiece guy.

I could, however, see some benefit to smaller throats on many tuba mouthpieces. Example: the Kelly 18 plays better than the original and has a smaller throat.

[Ken Herrick]

DO NOT put the mp in a vice or you will most likely leave all kinds of nasty marks on it.

Do it the EASY way. Making sure you can keep a good grip on the mp - like using a rubber grip sheet like for opening jars, have good SHARP drills, place one in a drill chuck, or even a tap handle, to give some leverage and turn it by hand. Work from the back bore in. Don't force - just let the drill do the work. Start with the first one which won't go through. Using 1/64 inch graduated drills and maybe metric set in 1/2 mm graduations as well, you can do as good a job as you would with a lathe.

Only "secret" is only take a very little bit at a time out.

With a drill press you will probably not get alignment and centering right.

TRUST ME - I have done it this way many times and gotten good results with no damage.

[windshieldbug]

The biggest problem is that you will only know how much is TOO much by getting there...
I recommend periodically taking measurements, playing the 'piece, and recording results.
And having a second mouthpiece to modify with the best results when you've gone too far with the first.


Been there, done that.

[Matt Walters]

Drilling out a mouthpiece is simple.
Get access to a lathe.
1. Take a tuba mouthpiece receiver that has a nice straight outside and carefully slit it open down one side. De-burr the inside so it won’t scratch your mouthpiece.
2. Fit the modified receiver onto the shank of the tuba mouthpiece.
3. Fit the receiver and mouthpiece in the lathe so that the mouthpiece does not wobble when it spins. You may need to experiment.
4. Install the drill bit of the size you want to drill the mouthpiece throat into the tail stock chuck that is trued to the lathe.
5. Set tail stock close to mpc and lock down in place.
6. Turn on lathe.
7. Crank the handle on the tail stock until the drill goes all the way in through the original throat.
8. Carefully remove the mouthpiece, wash it out and give it a play.

Now here comes the best part.

Say to yourself, “I think I like that. Since that worked, I’m going to drill it some more only two sizes bigger this time.”
Repeat the above steps until you have a paperweight instead of a mouthpiece.

[ghmerrill]

Now here comes the best part.

Say to yourself, “I think I like that. Since that worked, I’m going to drill it some more only two sizes bigger this time.”
Repeat the above steps until you have a paperweight instead of a mouthpiece.

This is why the "best practice" in such cases requires obtaining several mouthpieces (8 to 12 should be sufficient) so that you can have a range of results that you can then test side-by-side over a period of time and avoid the deceptive "this is different -> this is better -> more will be even better" approach. You should be able to do this for under $1,500 (plus the cost of the lathe and tooling to go with it, but you'll want that anyway for future projects). In the end you will probably decide that the original mouthpiece was the best, but then you'll have a dozen custom mouthpieces you can sell on Ebay or TubeNet for a profit.

(I have some small experience in these matters, having modified a Schilke 66 mouthpiece in this way many years ago -- though in the Hillbilly genre of machining and not using the multi-mouthpiece best practice. The original mouthpiece was better.)

[kingconn]

About 1977, I met Warren Deck. He was using a Bach 18 drilled out to 3/8". You can move a lot of air through a horn like this but it make the pitches a little less centered. Brass tends to grab as you drill it especially using the outer edges of the flutes. A reamer would be better.

[joh_tuba]

Goodgigs,

At least you answered the actual question!

Lots of excellent advice from smart folks!

[royjohn]

I agree that opening the throat of a tuba mouthpiece may, in many instances, be a bad idea, but let me suggest one more technique, if you must. you can buy a small split mandrel that will fit a dremel tool, Foredom-type flexshaft tool or a drill. A strip of sandpaper or emery paper fits into the split. Use any grit you think prudent. You could use something fairly coarse and then a fine or extra fine piece to polish up the throat. Just go slow, as even sandpaper going fast could be too fast. Play test and/or measure with a set of twist drills. Tape up the chuck if you can't keep it from contacting the sides of the mpc cup.

I personally like the idea of a smaller throat giving me a little resistance and possibly allowing me to use a little less air. But YMMV.

[iiipopes]

Another why: is it really the throat, or the mouthpiece equivalent of the venturi you want opened up, or a quicker backbore? Both Schilke and Bach understood that with the same throat the backbore was important to tone, pitch, and the general feel of the mouthpiece.

Oh, BTW, just to throw another wrench in the works: Bach trumpet mouthpieces were all made with the smaller throat and originally a reamer was included in each mouthpiece box so the player could enlarge the throat to his own preference. Now there is no reamer, but the same small throat, and all the new mouthpieces sound thin compared to my old early-Selmer 3C. Almost every Bach mouthpiece benefits from having the throat made at least one size larger (which is, of course, only a couple of thou, with the index numbered small bits). I had this done to a 3D and was able to put more air through the mouthpiece to facilitate higher range stability and tone.

And finally, not only the size of the throat, but what contour or taper? Conventional wisdom is that a shorter throat blended into the cup and backbore will result in a little broader tone and wider slots for those who do not like to pull slides, and a longer, more cylindrical throat will tighten up the slots and give a more centered tone at the expense of pulling slides more. So straight drilling a throat will result in needing more air to clear the venturi, and because it will effectively straighten and lengthen the throat, the slots may be tighter.

Bloke's advice if you must do it yourself is the way to go. But only if you must.

[sloan]

I just want the throat a hair larger

no one has asked this:

Why?

Perhaps he wants wider slots and the distribution of the strength of the slots moved higher in pitch.

At least, I *hope* that's what he *wants* - because that's what he'll get.

One hopes he has an excellent ear, plays a little trombone on the side, and likes to play F tuba parts on his favorite CC tuba.

[iiipopes]

That does beg the question: has anybody drilled a Miraphone C4 - TU23 out from its 7.5mm throat to something larger, say, 8.2mm?

[Paul Scott]

That does beg the question: has anybody drilled a Miraphone C4 - TU23 out from its 7.5mm throat to something larger, say, 8.2mm?

I've never done that but I have had success in opening up the throat on a Miraphone C3-TU21 to the size of an "O" drill bit.

Paul Scott

[iiipopes]

That does beg the question: has anybody drilled a Miraphone C4 - TU23 out from its 7.5mm throat to something larger, say, 8.2mm?

I've never done that but I have had success in opening up the throat on a Miraphone C3-TU21 to the size of an "O" drill bit.

Paul Scott

I prefer the one size larger, "P," .323"/8.2mm, but it sounds like it could be done. Hmm. But then again, I have a Blokepiece Imperial, so that should do.