Even tension easily...
The inner tube stretcher design is so simple to make and works so well. If you want to have even tension on a rectangular panel (ie. tall and narrow) the simple solution is to build an inner tube stretcher with two sections. Make a manifold to connect the two long side tubes and have a second manifold to connect two short end tube sections. Mark a scale (for vertical as well as horizontal) in tenths of an inch or in metric which is positioned below the diaphragm so you can see it clearly and when you place the new diaphragm on the jig use a marker to reference the diaphragm to the scale below. Make sure you do this for both length as well as width. Then when you stretch the diaphragm you can determine the percentage of stretch you want as you go. Stretch your length first and then your width. If you stretch to the same percentage of stretch in each direction then the tension should be even.
The inner tube stretcher design is so simple to make and works so well. If you want to have even tension on a rectangular panel (ie. tall and narrow) the simple solution is to build an inner tube stretcher with two sections. Make a manifold to connect the two long side tubes and have a second manifold to connect two short end tube sections. Mark a scale (for vertical as well as horizontal) in tenths of an inch or in metric which is positioned below the diaphragm so you can see it clearly and when you place the new diaphragm on the jig use a marker to reference the diaphragm to the scale below. Make sure you do this for both length as well as width. Then when you stretch the diaphragm you can determine the percentage of stretch you want as you go. Stretch your length first and then your width. If you stretch to the same percentage of stretch in each direction then the tension should be even.