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Turning down a mouthpiece shank (American --> British)
Posted: Tue May 23, 2023 12:15 pm
by arpthark
Is there enough material on, say, something that looks like a Bach 18 that it could be sanded down to fit in old English receivers?
Could an aspiring at-home tinkerer do this with fine grit sandpaper?
Re: Turning down a mouthpiece shank (American --> British)
Posted: Tue May 23, 2023 1:16 pm
by bort2.0
http://forums.chisham.com/viewtopic.php?t=10390
According to this post about outer diameters the small end of the shank... you're trying to get from .520" to .490"... that's a difference of 0.03", which is a little less than 1/32".
First -- I would measure the thickness of the metal at the shank of your mouthpiece
Then subtract 0.015" (half the total, since you're measuring just the thickness on one side) and see what's left
No idea what the measurements would be like, but maybe it'd work out okay? Or maybe it'd be too thin? Or maybe physically possible but just really awkward or difficult to do (and do well/consistenly)
I don't think fine sandpaper is necessarily the tool of choice here
I think my question for this would be, what's the *inner* diameter of a typical British shank mouthpiece vs American shank mouthpiece? Because as shank size increases, it's not like the inner diameter stays the same. The metal thickness across shank sizes is probably comparable, but the inner diameter changes.
Some mouthpieces (like Monette) have really thick walled shanks though. Thin-walled... IDK...
Re: Turning down a mouthpiece shank (American --> British)
Posted: Tue May 23, 2023 2:42 pm
by bloke
I'd probably turn down most mouthpieces.
Re: Turning down a mouthpiece shank (American --> British)
Posted: Tue May 23, 2023 3:02 pm
by 2nd tenor
arpthark wrote: Tue May 23, 2023 12:15 pm
Is there enough material on, say, something that looks like a Bach 18 that it could be sanded down to fit in old English receivers?
Could an aspiring at-home tinkerer do this with fine grit sandpaper?
No, it’s not a job for a home tinkerer.
It’s not unheard of for a mouthpiece to be turned down (in a lathe by a competent machinist) but the shank can become overly thin at the end and need to be trimmed back.
At one point I had a Bach 24W clone that had been turned down to suit a small shank receiver, it worked (fitted fine, etc,) but as I didn’t get on with the rim I sold that mouthpiece - IIRC I covered my costs.
If you have an Bach 18 to spare, enjoy using them and can get one turned down by a skilled person then that route is worth considering; it’s a gamble but it might end up being OK for you ‘cause similar has worked for others.
Re: Turning down a mouthpiece shank (American --> British)
Posted: Tue May 23, 2023 9:52 pm
by tofu
Re: Turning down a mouthpiece shank (American --> British)
Posted: Wed May 24, 2023 10:28 am
by bloke
I agree with Prof. tofu...
(except...) if it's just a Bach 18 knockoff (if not a "my gawd, this Bach 18 knockoff is magical !!!"), you could (??) try your hand at sanding it down...
- use cloth-backed "roll" sandpaper
- c. 250 grit offers quick progress, yet not too fast, and not too rough.
- keep changing pieces (to keep from using worn grit, so your sanding remains at the same rate.
- mark the outside of your rim (12 - 3 - 6 - 9...or more numbers), and keep track of which sides you've sanded, and do your very best to sand each portion of the rotation (including up-and-down) evenly.
- check with calipers for progress and for maintenance of roundness.
- finish off with 1000 grit or finer
- put a towel on the floor, so - if your mouthpiece spins off your makeshift fixture - it has a soft landing.
THIMK:
Rattling in the receiver indicates that the small end isn't being taken down as much as the large end...but TYPICALLY the OPPOSITE is what tends to happen with hillbilly shank sand-downs.
IF (??) you actually have a way to spin the mouthpiece between centers (actually ON CENTER and WITHOUT marking it up), you're likely to sand it more evenly, but (again) change out your strips to fresh sandpaper when they wear down.
(Wear googles and one of those not-effective-at-all-for-viruses-but-effective-for-brass-dust masks.) Also, wear long sleeves, because that crap can get into your skin...particularly the tender skin on the insides of your elbows...
Re: Turning down a mouthpiece shank (American --> British)
Posted: Sat Jul 19, 2025 8:04 am
by gocsick
Just turned down a Perantucci Euro PT-64 to slightly undersized American shank for the old Holton-ish Eb.
The tuba has a weird sized receiver.. A regular American shank (Yamaha 0.530" end OD) will work but stick out just a bit more than I would like.. The Euro (0.540") had very limited engagement (less than 1/2"). I have an old Holton Eb mouthpiece that fit the receiver very deeply with a 0.500" end OD.. but the cup shape was weird (narrow and deep) and it exacerbated the octave spread on this thing.
I picked up a used PT-64 from Blake for a fair price and liked how it played on both the tuba and the Eb Sousa... but it sat too shallow in both.. I figured if I screwed it up.. I wouldn't be out much.. and I would have learned something in the process. I should have been patient and taken it to work with me Monday and done it on a proper tool-room lathe.. Instead I did it this morning over a cup of coffee on the small 9x16 I have in my garage.
Freshly ground HSS cutting tool: Side and front relief 10 degrees, 1 or 2 degrees side rake and no back rake. Hit the tip with a diamond file to round the radius just a bit.
On the small 3 jaw I have for this I didn't quite have room to grip from the outside.. so wrapped some electrical tape around the jaws and grabbed from the inside.. stabilized with a dead center lubricated with plain wheel bearing grease. Runout was < 0.001"
Set compound rest for Morse.. Didn't measure it... I picked up a trick a while back to quickly copy tapers.. Take off the toolpost and hold a plate (known to be flat to within your tolerances) and hold it against the side of your compound rest then adjust carriage, cross slide, and compound rest so your plate also lies flat against the chucked up mouthpiece shank. I didn't bother to tram it, just checked clearance against top and bottom of the shank with a feeler guage and it felt good.
Decided to go for 0.520" This was so it would fit a little shallow in the tuba but not be so deep on the sousa. So 0.020" total diameter reduction.. so need to cut 0.010" off. Did 2 passes 0.08" and 0.002" with WD40 as cutting fluid. First pass was at 1000 rpm (~100fpm surface speed) second was at 1500. Feed was slow because the crank on the compound slide on this little lathe sucks. This lathe and setup was a little "flexy" too.. so I didn't back the tool off after the first pass I just ran in back and cleaned up the cut in reverse... not best practice but it works the way I ground the tool. Had a good surface finish second pass... quick cleanup with 800 grit paper lubed with WD40. Final dimension 0.519"
Have a full inch of engagement on the tuba...no wobble.. Happy with that. All in all a satisfying way to spend 45 minutes with some coffee.
Re: Turning down a mouthpiece shank (American --> British)
Posted: Sat Jul 19, 2025 12:14 pm
by arpthark
gocsick wrote: Sat Jul 19, 2025 8:04 am
Just turned down a Perantucci Euro PT-64 to slightly undersized American shank for the old Holton-ish Eb.
The tuba has a weird sized receiver.. A regular American shank (Yamaha 0.530" end OD) will work but stick out just a bit more than I would like.. The Euro (0.540") had very limited engagement (less than 1/2"). I have an old Holton Eb mouthpiece that fit the receiver very deeply with a 0.500" end OD.. but the cup shape was weird (narrow and deep) and it exacerbated the octave spread on this thing.
I picked up a used PT-64 from Blake for a fair price and liked how it played on both the tuba and the Eb Sousa... but it sat too shallow in both.. I figured if I screwed it up.. I wouldn't be out much.. and I would have learned something in the process. I should have been patient and taken it to work with me Monday and done it on a proper tool-room lathe.. Instead I did it this morning over a cup of coffee on the small 9x16 I have in my garage.
Freshly ground HSS cutting tool: Side and front relief 10 degrees, 1 or 2 degrees side rake and no back rake. Hit the tip with a diamond file to round the radius just a bit.
On the small 3 jaw I have for this I didn't quite have room to grip from the outside.. so wrapped some electrical tape around the jaws and grabbed from the inside.. stabilized with a dead center lubricated with plain wheel bearing grease. Runout was < 0.001"
Set compound rest for Morse.. Didn't measure it... I picked up a trick a while back to quickly copy tapers.. Take off the toolpost and hold a plate (known to be flat to within your tolerances) and hold it against the side of your compound rest then adjust carriage, cross slide, and compound rest so your plate also lies flat against the chucked up mouthpiece shank. I didn't bother to tram it, just checked clearance against top and bottom of the shank with a feeler guage and it felt good.
Decided to go for 0.520" This was so it would fit a little shallow in the tuba but not be so deep on the sousa. So 0.020" total diameter reduction.. so need to cut 0.010" off. Did 2 passes 0.08" and 0.002" with WD40 as cutting fluid. First pass was at 1000 rpm (~100fpm surface speed) second was at 1500. Feed was slow because the crank on the compound slide on this little lathe sucks. This lathe and setup was a little "flexy" too.. so I didn't back the tool off after the first pass I just ran in back and cleaned up the cut in reverse... not best practice but it works the way I ground the tool. Had a good surface finish second pass... quick cleanup with 800 grit paper lubed with WD40. Final dimension 0.519"
Have a full inch of engagement on the tuba...no wobble.. Happy with that. All in all a satisfying way to spend 45 minutes with some coffee.
Cool! I even understood some of those words!
Glad you’re finding a use for the 64!
Re: Turning down a mouthpiece shank (American --> British)
Posted: Sat Jul 19, 2025 12:17 pm
by York-aholic
If sanding is the way you choose to go, perhaps back the sandpaper up with a block of wood or a small scrap of aluminum. That way you know your resulting surface will be straight, ie no high or low spots.
Re: Turning down a mouthpiece shank (American --> British)
Posted: Sat Jul 19, 2025 12:34 pm
by bloke
re. turning down that shank:
excellent
a different tack: a Jarno #5 reamer (roughly 1/2" diameter range of the nothing-to-infinite Jarno taper) can be used to open up a receiver (without even removing it from an instrument) from "just under standard" to "standard", and a $100+ mouthpiece (which could - in the future - be found to also be suitable for another standard shank instrument) could remain standard shank.
Yes...Jarno reamers are expensive, but not quite as expensive - once the guy who actually makes them (whereby others re-sell them) is found.
The Jarno taper is within .XXXXX similarity in taper to the commonly-embraced Morse taper used for many "standard" shank tuba mouthpieces.
I own a #5 as well as a smaller #4.
I've used these reamers (besides for standardizing size) to changing goofball tapers to "the standard taper" (notice quotation marks).
My 1982 B&S Symphonie Modell featured a goofy taper (receiver made from a swell in the mouthpipe tube itself - covered by a cylindrical/protective nickel "over part". The correction (with the reamer) was subtle, and there was no danger of breaching the mouthpipe tubing wall...
...' same thing with a Rudy 5/4 that I once owned...goofy receiver...In order to correct that taper, I had to go from "fitting standard in the back and wobbling in the front" to (opening up the back until the reamer touched everywhere) enlarging it to the "euro" size.
Often, it's the (old European rotary tuba) receivers which are formed from the mouthpipe tube themselves which are the "goofy"-taper (atypical) ones.
also: I understand that you are a player, not a mouthpiece geek, not a repair-guy, (though very knowledgeable/capable in metals and machinery) and your immediate solution cost you $0.00
Re: Turning down a mouthpiece shank (American --> British)
Posted: Sat Jul 19, 2025 2:33 pm
by gocsick
I didn't know it was possibly to get Jarno taper reamers. I only know of them from old machines... the spindle on some (all?) Monarch lathes are Jarno taper... and some specialty grinding tools.
I had to look it up . The difference between Morse and Jarno is much closer than I ever realized. The difference in taper is only 0.025" over a 1 foot length.. Close enough to get a good seal on a mouthpiece but still be easily releasable... Far enough out that it would wreck tooling if you tried to use them interchangeably.
I thought about replacing the receiver.. but was worried about opening a can of worms.. and as you said turning the shank didn't cost me anything (well it could have cost me the $70 I paid for the thing of I screwed it up ).
Re: Turning down a mouthpiece shank (American --> British)
Posted: Sat Jul 19, 2025 3:05 pm
by bloke
I bought one with a square end, drilled a hole in it, and I - LOL - ran a fat nail through the hole (as a "T" handle).
I usually user.e it by hand, but occasionally mount and spin the reamer.
Yeah...The difference in taper is - as far as a mouthpiece and receiver made of soft brass are concerned - negligible...
...and - if doing it by hand - the "control" error is astronomical - compared to the numerical difference in taper.
Those that I've been able to acquire have been spiral.