I have a plastic tenor mouthpiece that plays great (after refacing), but 
has a hairline crack in the shank.  About an inch long (goes up to where 
the "body" of the mouthpiece starts).  It's nearly invisible until the 
mouthpiece is on a neck cork, which opens it up a little.  My first 
thought was Super Glue (cyano-acrylic), but I don't know how the crack 
could be safely opened up enough to sneak the glue in without snapping 
the mouthpiece.

So I'm thinking of making the crack wider with a Dremel (cutting wheel 
or a really thin diamond bit) and filling it with 2-part acrylic, which 
should chemically bond to the existing plastic.  That bond may be strong 
enough to withstand a lifetime of being pushed onto a neck cork.  I 
suppose if I used the cutting wheel, the gap might be narrow enough that 
Super Glue would work.  Also maybe putting a metal band on it as well 
(there's a standard copper pipe size that fits pretty closely).

So - How wide a gap can Super Glue be used in?  When a metal band is 
used, does it need an adhesive, or is it just a really good friction 
fit?  Anyone have experience with acrylic or CA glues in this tensile 
stress kind of situation (where the bond is being pulled apart)?

I know that the amount of work involved would normally not be worth it 
(maybe if this was someone's favorite mouthpiece), but I just want to 
learn how to fix this.  Any advice, experiences, anecdotes?  Thanks.

Dan



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Hi Dan,

Last time I fixed a crack like that, I took a drumstick, wrapped it 
in wax paper and put it into the bore of the mouthpiece to open the 
gap. I used CA gel glue to in the crack, then pulled the drumstick to 
close the gap. The wax paper keeps the stick from getting glued to 
the piece.

Make sure you let the CA glue set up for a minimum of 24 hours - I 
find 48 to be best.


--- In MouthpieceWork@yahoogroups.com, Dan Torosian <dtorosian@e...> 
wrote:
> I have a plastic tenor mouthpiece that plays great (after 
refacing), but 
> has a hairline crack in the shank.  About an inch long (goes up to 
where 
> the "body" of the mouthpiece starts).  It's nearly invisible until 
the 
> mouthpiece is on a neck cork, which opens it up a little.  My first 
> thought was Super Glue (cyano-acrylic), but I don't know how the 
crack 
> could be safely opened up enough to sneak the glue in without 
snapping 
> the mouthpiece.
> 
> So I'm thinking of making the crack wider with a Dremel (cutting 
wheel 
> or a really thin diamond bit) and filling it with 2-part acrylic, 
which 
> should chemically bond to the existing plastic.  That bond may be 
strong 
> enough to withstand a lifetime of being pushed onto a neck cork.  I 
> suppose if I used the cutting wheel, the gap might be narrow enough 
that 
> Super Glue would work.  Also maybe putting a metal band on it as 
well 
> (there's a standard copper pipe size that fits pretty closely).
> 
> So - How wide a gap can Super Glue be used in?  When a metal band 
is 
> used, does it need an adhesive, or is it just a really good 
friction 
> fit?  Anyone have experience with acrylic or CA glues in this 
tensile 
> stress kind of situation (where the bond is being pulled apart)?
> 
> I know that the amount of work involved would normally not be worth 
it 
> (maybe if this was someone's favorite mouthpiece), but I just want 
to 
> learn how to fix this.  Any advice, experiences, anecdotes?  Thanks.
> 
> Dan
> 
> 
> 
> -- 
> No virus found in this outgoing message.
> Checked by AVG Anti-Virus.
> Version: 7.0.308 / Virus Database: 266.11.8 - Release Date: 
5/10/2005

Another thought would be to band the shank.

Toby
  ----- Original Message ----- 
  From: Dan Torosian 
  To: Mouthpiece Work 
  Sent: Tuesday, May 17, 2005 10:53 AM
  Subject: [MouthpieceWork] Cracked shank


  I have a plastic tenor mouthpiece that plays great (after refacing), but 
  has a hairline crack in the shank.  About an inch long (goes up to where 
  the "body" of the mouthpiece starts).  It's nearly invisible until the 
  mouthpiece is on a neck cork, which opens it up a little.  My first 
  thought was Super Glue (cyano-acrylic), but I don't know how the crack 
  could be safely opened up enough to sneak the glue in without snapping 
  the mouthpiece.

  So I'm thinking of making the crack wider with a Dremel (cutting wheel 
  or a really thin diamond bit) and filling it with 2-part acrylic, which 
  should chemically bond to the existing plastic.  That bond may be strong 
  enough to withstand a lifetime of being pushed onto a neck cork.  I 
  suppose if I used the cutting wheel, the gap might be narrow enough that 
  Super Glue would work.  Also maybe putting a metal band on it as well 
  (there's a standard copper pipe size that fits pretty closely).

  So - How wide a gap can Super Glue be used in?  When a metal band is 
  used, does it need an adhesive, or is it just a really good friction 
  fit?  Anyone have experience with acrylic or CA glues in this tensile 
  stress kind of situation (where the bond is being pulled apart)?

  I know that the amount of work involved would normally not be worth it 
  (maybe if this was someone's favorite mouthpiece), but I just want to 
  learn how to fix this.  Any advice, experiences, anecdotes?  Thanks.

  Dan



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  Checked by AVG Anti-Virus.
  Version: 7.0.308 / Virus Database: 266.11.8 - Release Date: 5/10/2005



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I have not tried gluing a crack shut.  Seems to me that it would just 
crack open again.

I usually band by wrapping the shank with thin metal wire (brass music 
wire).  Then I coat it with epoxy.  Shaping the epoxy to look good is a 
pain with this method.  There are a few pics in the Photo area.

A metal band is probably better if you can saw one off a metal pipe or 
can get one made by a machinist.  Epoxy would be needed to keep the 
band on unless the shank was also machined for a snug fit.

Dan, I have never been successful with glues for shank cracks.  Banding 
in some fashion is the only solution.
 
I usually use aluminum tubing, dress the edges well, and use an abrasive 
wire brush thingy to give a brushed look to it. 
 
I dress the shank to smoothly allow the band to slide on.  It is not 
necessary for the band to completely cover the crack, many times that is 
just not possible.  What is wanted is to prevent the shank from 
expanding when on the neck cork, opening the crack. 
 
So, fit the band to the shank first.  Then, mask off the outside of the 
band with tape.  I use common electrical tape.  Mask off the mouthpiece 
right even with the edge of the band.
 
Rough up the surface of the shank with sandpaper.  Wipe everything clean. 
 
Mix up some 5 minute or 15 minute epoxy.  I have found that 5 minute 
epoxies are more brittle, and yellow within a few years.  Apply the 
epoxy to the shank AND to the inside of the band.  This way there should 
be no air bubbles.  Push on the band and wipe off all excess. 
 
Keep checking every few minutes for any additional drips until the epoxy 
begins to set up. 
 
As the epoxy gels, but before it is hard (check the remaining epoxy on 
your mixing card), remove the tape, and using alcohol wipe away any that 
epoxy that may be on the mouthpiece or outside of the band.
 
After the epoxy is complete set, I mask off the rest of the mouthpiece 
and spray clear lacquer on the band to prevent it from darkening.
 
I have also used copper, once when I ran out of aluminum and could not 
find the right size tubing.  I did a Selmer S80 Tenor with that.  Well, 
the guy loved it, and loved the "sonic qualities" of the copper.  ???  
It's a just a band on the shank.  Who am I to argue?  Well, he said he 
told that to his friends.  So, next thing I know, I am getting boxes and 
boxes in the mail, perfectly good mouthpieces, wanting the copper bands, 
and raves about the sonic improvement. 
 
Normally I would have felt guilty for that, but S80's have very thin 
shanks and DO crack easily.  I consider it preventative.  And they 
wanted to throw money at me. 
 
If you find there is any "sonic quality" improved by using copper... 
OK.  But copper does work well as a banding material, too.
 
Paul


Dan Torosian wrote:

> I have a plastic tenor mouthpiece that plays great (after refacing), but
> has a hairline crack in the shank.  About an inch long (goes up to where
> the "body" of the mouthpiece starts).  It's nearly invisible until the
> mouthpiece is on a neck cork, which opens it up a little.  My first
> thought was Super Glue (cyano-acrylic), but I don't know how the crack
> could be safely opened up enough to sneak the glue in without snapping
> the mouthpiece.
>
> So I'm thinking of making the crack wider with a Dremel (cutting wheel
> or a really thin diamond bit) and filling it with 2-part acrylic, which
> should chemically bond to the existing plastic.  That bond may be strong
> enough to withstand a lifetime of being pushed onto a neck cork.  I
> suppose if I used the cutting wheel, the gap might be narrow enough that
> Super Glue would work.  Also maybe putting a metal band on it as well
> (there's a standard copper pipe size that fits pretty closely).
>
> So - How wide a gap can Super Glue be used in?  When a metal band is
> used, does it need an adhesive, or is it just a really good friction
> fit?  Anyone have experience with acrylic or CA glues in this tensile
> stress kind of situation (where the bond is being pulled apart)?
>
> I know that the amount of work involved would normally not be worth it
> (maybe if this was someone's favorite mouthpiece), but I just want to
> learn how to fix this.  Any advice, experiences, anecdotes?  Thanks.
>
> Dan
>
>
>
> -- 
> No virus found in this outgoing message.
> Checked by AVG Anti-Virus.
> Version: 7.0.308 / Virus Database: 266.11.8 - Release Date: 5/10/2005
>
>
>
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>
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