Bob Stewart asks about calculating the pneumatic cloth width [180814
MMDigest].  My paper, "Force development in pneumatic motors," shows
the effect of the cloth in developing a closing force.  As Bob notes,
the cloth must not be too wide or else the pneumatic will not close
properly.  A suitable formula would be

  cloth width = board width plus 2 times the board thickness.

For the example of a 2-tier stack with 1-inch width boards of
thickness 3/16 inch, the correct cloth width would be

  1 inch plus 3/16 + 3/16 inch = 1-3/8 inch.

This is the open span measurement of the pneumatic.

If the cloth is too narrow, the open span of the pneumatic will
suffer.  In Bob's example, 1-5/8 inch is too much.

Paul Rumpf
Melbourne, Australia

 [ Reference:
 [
 [ "Force Development in Pneumatic Motors", By Paul Rumpf
 [   https://www.mmdigest.com/Archives/Digests/200812/2008.12.15.06.html 
 [
 [ Mechanical Forces Developed in Pianola Pneumatic Motors
 [  (rumpf_1.doc, 65 kb) -- by Paul Rumpf, November 2008
 [  http://www.mmdigest.com/Gallery/Tech/rumpf_1.doc 
 [
 [ Mechanical Forces Developed in Pianola Pneumatic Motors
 [  (rumpf_1.pdf, 122 kb) -- by Paul Rumpf, November 2008
 [  http://www.mmdigest.com/Gallery/Tech/rumpf_1.pdf 
 [
 [ -- Robbie