I have been working on some alto mouthpieces with a large window. 
14mm of the side rails are flat and so are actually a part of the 
table. No matter how I hold the mouthpiece, the table ends up arched, 
high in the middle. The piece plays well with an Olegature moved up 
far to the front as possible, but the stock 2-screw lig can't be 
moved up as far and so there are leaks.

When I use 600 grit paper, it is pretty hard to get the piece moving 
so there is more pressure on the back of the table. I don't use 
lighter grit paper because I'll go through a hundred sheets to make 
any progress. I haven't had this kind of trouble with hany other 
mouthpiece so I'm guessing its the combination of bronze with a large 
window that is throwing me. I was able to get the tables flat on 
plastic and hard rubber pieces with the same configuration.

Maybe I need to invest in a lapping table. How would that help me?

Also, I just invested $50 in carbon paper from the hardware store. Is 
there a cheaper way to do this?

Help!
Jon Lloyd

I would say don't press so hard on the piece...let the paper do the 
work. If you are sanding dry now, try wetting the paper with water, 
or, if you can stand the smell and mess, kerosene as a lubricant. 
Lubricant really helps the 'stiction' think in getting it started 
moving.

--- In MouthpieceWork@yahoogroups.com, "stencilmann" <jg_lloyd@s...> 
wrote:
> I have been working on some alto mouthpieces with a large window. 
> 14mm of the side rails are flat and so are actually a part of the 
> table. No matter how I hold the mouthpiece, the table ends up 
arched, 
> high in the middle. The piece plays well with an Olegature moved up 
> far to the front as possible, but the stock 2-screw lig can't be 
> moved up as far and so there are leaks.
> 
> When I use 600 grit paper, it is pretty hard to get the piece 
moving 
> so there is more pressure on the back of the table. I don't use 
> lighter grit paper because I'll go through a hundred sheets to make 
> any progress. I haven't had this kind of trouble with hany other 
> mouthpiece so I'm guessing its the combination of bronze with a 
large 
> window that is throwing me. I was able to get the tables flat on 
> plastic and hard rubber pieces with the same configuration.
> 
> Maybe I need to invest in a lapping table. How would that help me?
> 
> Also, I just invested $50 in carbon paper from the hardware store. 
Is 
> there a cheaper way to do this?
> 
> Help!
> Jon Lloyd

As I have said before, this can be maddening.  You think you have it down,
then a new shape and material in your hand will cut different.  Different
grit papers can cut different.  There are several variables.

One strategy is to pick one side of the arch you have and try to make it
longer and flatter.  If you are trying to open the tip, work the heel side.
 The facing length will be super long until you chase the table up the
piece.

If you work the tip side of the arch, the tip opening might get smaller. 
You can also not worry a lot about getting the last 1/4"-3/8" of the heel
flat.

The other strategy is to attack the top of the arch with small scraps of
sandpaper under your finger.  Try to create a small low spot in the center
of the table.  Now you can flip the piece over and it wont be rocking on a
single high spot.  You can slowly make a flat section in the middle of the
table that keeps getting bigger.

There is a natural tendency for the leading edge of table to dig into the
paper as you draw it across it.  Its like when a car skids to a halt and
the front tires get more wear.

So when pulling towards the heel I often lean the piece away from the heel
to offset this force "couple".

Use small piece of glass against the table and probe around the edges of
the table with a .0015" feeler to gage your progress.  If it is getting
better, it is best to continue doing the same exact strokes until your
hand/finger falls off.  Shifting your technique will most likely start
removing material from a different place.

I use a Sierra Bravo Lapping Plate that stretches and clamps down sandpaper
flat.  I mostly use this for heavy cutting on SS and when I have to remove
a lot of material.  I use 320 and 220 grits.

I have been quite fond of the adhesive backed mylar film sandpaper.  I use
the 15mu and 45mu grits.  I then use a couple of strips of 1000 grit for
fine work.  I have a stack of other grits, but I'm starting to zero in on
this subset.  I think the automotive store might be a better source as
compared to a hardware store.

Another help is to have a vacuum handy.  It is real nice to be able to get
the filings and sanding dust out of your way.  


		
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Your lapping plate sounds cool...couldn't find anything like it on 
the web...any clues...

--- In MouthpieceWork@yahoogroups.com, Keith Bradbury 
<kwbradbury@y...> wrote:
> As I have said before, this can be maddening.  You think you have 
it down,
> then a new shape and material in your hand will cut different.  
Different
> grit papers can cut different.  There are several variables.
> 
> One strategy is to pick one side of the arch you have and try to 
make it
> longer and flatter.  If you are trying to open the tip, work the 
heel side.
>  The facing length will be super long until you chase the table up 
the
> piece.
> 
> If you work the tip side of the arch, the tip opening might get 
smaller. 
> You can also not worry a lot about getting the last 1/4"-3/8" of 
the heel
> flat.
> 
> The other strategy is to attack the top of the arch with small 
scraps of
> sandpaper under your finger.  Try to create a small low spot in the 
center
> of the table.  Now you can flip the piece over and it wont be 
rocking on a
> single high spot.  You can slowly make a flat section in the middle 
of the
> table that keeps getting bigger.
> 
> There is a natural tendency for the leading edge of table to dig 
into the
> paper as you draw it across it.  Its like when a car skids to a 
halt and
> the front tires get more wear.
> 
> So when pulling towards the heel I often lean the piece away from 
the heel
> to offset this force "couple".
> 
> Use small piece of glass against the table and probe around the 
edges of
> the table with a .0015" feeler to gage your progress.  If it is 
getting
> better, it is best to continue doing the same exact strokes until 
your
> hand/finger falls off.  Shifting your technique will most likely 
start
> removing material from a different place.
> 
> I use a Sierra Bravo Lapping Plate that stretches and clamps down 
sandpaper
> flat.  I mostly use this for heavy cutting on SS and when I have to 
remove
> a lot of material.  I use 320 and 220 grits.
> 
> I have been quite fond of the adhesive backed mylar film 
sandpaper.  I use
> the 15mu and 45mu grits.  I then use a couple of strips of 1000 
grit for
> fine work.  I have a stack of other grits, but I'm starting to zero 
in on
> this subset.  I think the automotive store might be a better source 
as
> compared to a hardware store.
> 
> Another help is to have a vacuum handy.  It is real nice to be able 
to get
> the filings and sanding dust out of your way.  
> 
> 
> 		
> __________________________________
> Do you Yahoo!?
> Yahoo! Mail - You care about security. So do we.
> http://promotions.yahoo.com/new_mail

There are some photos on the MP Work site under Sanding-Lapping.  There is
an Email contact in the caption.


		
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Thanks Keith and Jeff, that was great help. Combining several 
suggestions did the trick:

- Making a low spot in the middle of the table and then making it flat
- Wetting the paper to avoid applying so much pressure that the the 
butt digs in
- Finding the right point to apply downward pressure (about 2/3 from 
the end of the table to the start of the curve)
- Painting the table with a dry erase maker so I could tell if a 
single swipe across the paper was lapping the entire table evenly (my 
own little idea I got from leveling toneholes). Of course, this has 
to be done with dry paper.

This group is just awesome!
Jon

>Painting the table with a dry erase maker...

Good one!  I have resorted to using pencil scribble on the table in the
past.  

Marker on the side rails also helps you to learn how to zero in on the
right spots.


	
		
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What I have been doing (adapted from my surface grinding experience) 
is to angle the piece slightly one way or the other alternately as I 
work. Then by the angle of the scratch marks you can tell if you are 
making progress. This is also a great way to polish, as you index to 
increasingly finer paper, reverse the angle of the piece and you can 
tell when you have removed all the scratches from the previous grit.

--- In MouthpieceWork@yahoogroups.com, Keith Bradbury 
<kwbradbury@y...> wrote:
> >Painting the table with a dry erase maker...
> 
> Good one!  I have resorted to using pencil scribble on the table in 
the
> past.  
> 
> Marker on the side rails also helps you to learn how to zero in on 
the
> right spots.
> 
> 
> 	
> 		
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