<html> <body> Hi Jack,                  Samick is using them in the Renner action/  Knabe line of pianos,  3 different thickness of spring across the key board.  .7mm,  .6mm,  .5mm.   You will hear passionate arguments for and against.  The keyboard should be weighted off at 67gms tapered to 60gms at the end of the spring section, with the springs disconnected.   Springs are the connected, and touch weight adjusted from 54gms in bass to 48gms extreme treble. I will be going to Korea next week to set up new touch weight parameters. I like the lowering of mass. and the increase in up weight, from the use of springs.   Springs should not support any more than 15gms of down weight in the bass and 8-10 gms in the treble. As for making weighting more difficult.    I feel you can get very even weighting, and use a pre mapped or CNC weight off pattern, the springs are simple to adjust once you get the hang of it. Springs have been used in the past to hide a multitude of sins at the factory level.   Fudging geometry and friction problems.    When used correctly, I love them. Regards Roger Technical Consultant Samick Music Corp. At 09:36 PM 4/27/2005, you wrote: <blockquote type=cite class=cite cite=""> I would like to know some things about wippen support springs. Who uses them?  Do companies still continue to use them?  Should they be removed?  I know they make key weighting difficult.   Jack Houweling    </blockquote></body> </html>