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I am very intrested in the thought of drilling out the backbore of a mouthpiece. I just want to know 1) how to do it 2) how much material should I remove? 3) What exactly is the desired effect?
I do have access to a lathe and drill presses and just about any type of metal working tools imaginable. So the actual act of doing it would be no problem. I currently have 4 "Identical" mouthpieces, An original Mirafone C4, a Miraphone TU-23, and 2 Yamaha 67C4's. I really don't think I'm prepared to possibly ruin my good Mira(F)phone's but I think the pair of Yamaha's would be good candidates. I don't really play on either one anymore but maybe I will make one of them sound great.

BTW I know I again might get flamed for another "hardware" topic but, hey I am just a curious guy. I am just simply interested in the effect's of this experiment and am not looking for a solution to any of my numerous playing problems/habits.

tubatom91 wrote:I am very intrested in the thought of drilling out the backbore of a mouthpiece. I just want to know 1) how to do it 2) how much material should I remove? 3) What exactly is the desired effect?
I do have access to a lathe and drill presses and just about any type of metal working tools imaginable. So the actual act of doing it would be no problem. I currently have 4 "Identical" mouthpieces, An original Mirafone C4, a Miraphone TU-23, and 2 Yamaha 67C4's. I really don't think I'm prepared to possibly ruin my good Mira(F)phone's but I think the pair of Yamaha's would be good candidates. I don't really play on either one anymore but maybe I will make one of them sound great.

BTW I know I again might get flamed for another "hardware" topic but, hey I am just a curious guy. I am just simply interested in the effect's of this experiment and am not looking for a solution to any of my numerous playing problems/habits.

No flaming relevant, at least from me, as I have worked on most of my current mouthpieces. I will not start out with the full dissertation, but center on the most important point:

Which sonic changes do you want as the result of the backbore modifications?

And a statement of the obvious: If you don’t like a mouthpiece at all and hear no potentials in it, then you can go on modifying it for ever, and you will still dislike it.

Klaus

I think, personally, the mouthpieces feel a bit "choked" and it seems that I can't quite put the air through them quite like my PT-88's or my Kellyberg. I love the backbore size on the kellyberg mouthpieces, I'm considering buying a stainless version.
I do however like the cup size and depth. My favorite mouthpiece of the 4 is the original C4, It is old and has the great stripped rim. (I have to coat it in nail polish every once in awhile).

Which end does the bit enter. The cup side or the shank side. I dont want to do this backwards!

ok thanks. I will probably think about this project for awhile before actually doing it. Kind of like a waiting period. I will let everybody know how it goes when I do set myself on doing it. BTW Whtat does anybody think will happen? I mean I know I don't like it but I am not sure what to expect once I do this to my mouthpiece.

Any other opinoins?

In general, a larger backbore equates to a mellower, darker sound. Using bloke's procedure, you will also be opening up the throat of the mouthpiece, so you may find it takes more air to get the sound going than before. You will essentially be eliminating any taper from the throat to backbore, so you lose the efficiency that a taper in that area helps create.

Also in general, a larger throat/backbore will help open up your low register (if you move the air to handle it), but the compromise is a more difficult time making the high register speak.

Be prepared for a less-pointed attack after you open up the throat/backbore. You will have to work harder to get clean articulation away from the bell.

Some will say that a larger mouthpiece throat/backbore makes it easier to play loud or, at the least, increases the volume point at which the sound starts to "break up."

If that's the change in direction you're looking for, great!

I'm thinking that, that is pretty much what I want. Thank you guys very much. And bloke you made this quite a bit simpler than I would have made it. I will let you know on the results

Would it be better to keep one that you like, and then sell off three (even if for cheap) and pick up a Marcinkiewicz mouthpiece (I don't remember which one) that will pretty much be the same thing as what you will end up with?

If you are doing this solely for the experience, by all means do it. If I were thinking about using these mouthpieces seriously again, I might be more cautious.

bloke wrote:Those cheap tapered reamers (1/8" - 1/2") that can be found for sale in auto parts stores, actually, are not too terribly bad for homespun attempts at increasing the size of backbores (final larger end) of tuba mouthpieces.

Otherwise known as "E-Z-Outs." I've used those to repair out-of-round mouthpiece shanks (boy, is that common) myself and they do work very well. I've had more success with the "spiral" kind. They are quite hard, so use lots of oil and GO SLOW, only using the tool by hand...a 12-point socket (fit to match the end of the E-Z-Out) on a ratchet with an extension makes a nice driver.

bloke wrote:Those cheap tapered reamers (1/8" - 1/2") that can be found for sale in auto parts stores, actually, are not too terribly bad for homespun attempts at increasing the size of backbores (final larger end) of tuba mouthpieces.

I have re-reamed the backbore on a Schilke bass trombone mouthpiece to get it back to the standard Schilke backbore after shortening to correct my tendancy to blow everything flat. Once you cut the stupid long shank off to a manageable size and turn the outside diameter back to spec(in this case Dennis Wick spec) you are left with a backbore that makes the mp play stuffy. I have an old beat up 60 that I used for a pattern to make a mandrel out of. I took a hard wood, Black Locust I think, lathe turned it just oversized and finished shaping it using the inside backbore on the mp with sanding grit and and the mandrel chucked in a drill. After getting it to match the mp backbore I then went to the good mp and repeated the process in reverse. I got it real close to original and I now have a 60 that I can play in tune on my Besson 943. I really love the Schilke mp but I don't own a single horn that can compensate for that long shank.

tubatom91 wrote:Any other opinoins?

Use two identical mouthpieces. Experiment with one. Keep opening it up and record each increment. Then play it. Keep the results, too.

You'll only find out how much is too much by going too far. Since you've been keeping records, make that one a paperweight, then take the other one and open it up as far as your last good result.

windshieldbug wrote:

tubatom91 wrote:Any other opinoins?

Use two identical mouthpieces. Experiment with one. Keep opening it up and record each increment. Then play it. Keep the results, too.

You'll only find out how much is too much by going too far. Since you've been keeping records, make that one a paperweight, then take the other one and open it up as far as your last good result.

I almost agree with you. My own approach has been to stop, when I have achieved my goal. Thereby I have avoided ruining any mouthpices so far.

Klaus

bloke’s tech advices are all right. Only in one matter I am somewhat doubtful: the longer the cylindrical part of the throat, the more the mouthpiece determines the intonation and lipping gets harder. Tight slots are fine, if they are placed where you want them, but how often does that happen with tubas?

If I can get my hands on the right tools, I rather let the narrowest point just after the funnel in the bottom of the cup stay untouched. I try to open the opposite funnel from the stem end.

And then I mostly open up the widest end of the backbore. In some cases I only chamfer/undercut the lower edge to avoid turbulences.

Klaus

bloke’s suggestion for getting a conical throat takes a craftsmanship not bestowed on me.

There may be a bit of cheating in my modifications insofar that I used some pro-level reamers from a friend’s machine shop for working on the area of the backbore closest to the throat. And I secured the reamers by means of a vice like bloke told, even if this happened before I knew much about bloke.

My own hand tools are three cheaper and slightly modified reamers intended for cleaning up smoking pipes plus a conical reamer from a hardware store.

Klaus

Okay. I would recommend great caution on modifications at this point. I would also have some questions for the OP.

If you just blow air through the mouthpiece, does it back up on you? Before altering the mouthpiece I would examine the potential for operator "improvement". I often find that the backpressure many players expeirence is built in at the embouchure rather than having anything to do with the equipment. I have not found a mouthpiece the would back up when I just blow air through it (unless it's a trumpet mouthpiece). Before doing any thing, try "The Spit Valve Drill", posted sometime earlier by me first, then look at your options from there.

Now, as to drilling the mouthpiece, several things will happen. The great "secret" behind mouthpiece design is what is called the "straight pipe". At the throat of the mouthpiece is a drilled hole of a specific length, before the taper begins to expand to the stem of the mouthpiece. The longer this 'straight pipe" is, the better the slotting of the notes will be, but the sound will tend to go a bit brittle. The shorter it is, the better the sound is but the slotting goes away.

Examples:
PT88 short straight pipe = big dark sound with a tendancy to slot well but not as tightly as some people would like;
Marty Erickson ME5: longer straight pipe = a bit brighter with better slotting, will articulate more cleanly but some may find the sound a little bright for their tastes.

As you drill a mouthpiece this straight pipe becomes longer, so if you go too far it may change the overall effect rather drastically. Just remember - it's really hard to put it back the way it was.

Just my $0.02.
Roger

I think that I am going to try this experiment tonight. I have done a bit more research and found that the Yamaha 67C4 throat is 8.1mm (.318") which is identical to my PT-88's that I like soo much. Which means of course this wont be an experiment to "even" the two mouthpieces out. I just think these two mouthpieces will make excellent examples of what a "larger than stock" throat can do for the sounds that come out of the bell or just how it feels to the player. I tend to enjoy more or less shocking my band directors with some of my "experiments" or shenanigans. I even shocked them with my giant mute today. But this isn't really about that, it's just an added benefit. I think I'm just a tinker-er by nature. But anyways I think that I'll open this mouthpiece up to where I think I am satisfied and then STOP. I certainly don't want to open this mouthpiece up to where it's un-playable or to where I deem it un-playable . Maybe we will all learn something from this experiment. I know that I've learned quite a bit from Roger when I came and bought my horn last year and that was before I even played my new horn. And I certainly thank all of the posters on this particular thread (Bloke, imperialbari, Todd) for teaching me quite a bit about this subject. I may not get the results till tomorrow but I'll plug it into my Besson 3 valve tonight (My primary horn is at school).

I just finished. This was pretty cool, the only trouble I had was after I was tunring the mouthpiece for awhile and my arm started getting tired . The results are inconclusive, I'd love for a person that knows alot more about this stuff to try this out. I bored it out a bit larger than originally anticipated, I think I went further because the 67C4 throat is already bigger then the original C4/TU23, which I just learned today. Both the stock 67C4 and the new mod. 67C4 sound great on my Besson and I am learning to love this old tank of a horn . The low register is great!(talking of mouthpiece alterations). I like the way this turned out, I am sure I will learn a little more once I plug it into my CC, I'm not really used to this Besson. Like I said before, I am sure that a pro player could give you guys a little more insight as to what kind of monster I've created.

I will call this a success. And this was easier than I though it was going to be, thanks to you guys! If you are ever in Aurora/Chicagoland and you want to try out this mouthpiece let me know

I thought at one point Marc. made a piece that was a C4 replicate with a bigger throat, similar to the desires of the OP. Maybe a "Solo" model of someone of high repute?

I used this piece in Wind Symphony today, playing Elgar's Enigma Variations. This mouthpiece is great at high volumes. I had no problem pushing the volume up without worrying about loseing the tone. I was surprised that while this did help the low register, the high register is still there and sounds just as good as it did pre-modifacation. I can't really imagine doing this test to anything other than P.O.S. mouthpieces but I do think the whole reverse taper theory has a lot of merit. IMO this experiment was a success, I might of course be tricking myself into thinking I did somthing great with this modifacation but I think I like it. My band director looked at me funny when I showed him the mouthpiece, he thought I was using a stock 67C4 and was very confused considering I almost exclusivley use my PT-88/PT-88+ in Band/Orchestra. It was more of a "why are you playing a Yamaha....Oh I get it now." I think I am interested in some other mouthpiece now...

(How much is one of those "bloke-pieces" again?)

I agree. I don't know why a particular throat design works, either. For example, I am more secure on the high range of my Besson with its really, really deep Wick 1 with a large throat (8.42mm and open backbore) than I am on any shallower mouthpiece or smaller throat mouthpiece on this on any other horn I have played.

Probably for the same reason a jazz or commercial lead trumpet player tends to use a mouthpiece with a larger throat: can utilize more air. What I mean by that is a larger velocity of air, not necessarily volume, with Bernoulli's principle: greater velocity, lower pressure, facilitates higher pitch.