Hi All, I'm starting to have various sizes of vacuum-operated
pouch tools manufactured, but I've run into a bit of a problem.
Specifically, the question is: What's the correct contour of a pouch?

About the only parameter that everyone seems to agree on is that the
depth of the pouch should be 1/8" in the center.  On the other hand,
the shape of the 'dish' seems to vary widely.  I've attached four
pictures/diagrams of pouch tools and it's easy to see the differences.

If there is an optimum contour, how is it defined?  Does it vary from
manufacturer to manufacturer?

I look forward to your opinions.

Musically,
John A Tuttle
Player-Care.com
Brick, New Jersey, USA

 [   contour of pouch 1
 [ http://www.mmdigest.com/Attachments/18/04/18/180418_050446_contour-1.jpg
 
 [   contour of pouch 2
 [ http://www.mmdigest.com/Attachments/18/04/18/180418_050446_contour-2.jpg
 
 [   contour of pouch 3
 [ http://www.mmdigest.com/Attachments/18/04/18/180418_050446_contour-3.jpg
 
 [   contour of pouch 4
 [ http://www.mmdigest.com/Attachments/18/04/18/180418_050446_contour-4.jpg
 

 [ I believe the unsupported portion forms a catenary, the curve of a
 [ hanging chain.  See https://en.wikipedia.org/wiki/Catenary  -- Robbie