Posted by Rick Denney on February 04, 2003 at 12:11:59:
In Reply to: Big Finger Buttons posted by Lew on February 04, 2003 at 08:35:56:
Off-center application applies a tiny "moment" to the piston, but it really is tiny. If you press the valve straight down but a half-inch off-center, the force couple is effectively resisted by one-tenth of your application force at the bottom of the valve, assuming the valve is five inches long. This is miniscule.
On the other hand, if you can't reach the valve, you'll put your finger on the edge of the button, which will push the top of the valve sideways. If you park your finger right on the corner of the button, and apply force in a 45-degree angle, then the top of the valve will have to resist 71% of your application force. That's seven times the lateral force from an off-center, but straight application.
Consequently, I think it is much better to have offset or oversized buttons that fit, so that the player can push them straight down, than to push in the center of the valve with a lateral force because the finger won't actually reach the center comfortably.
Rick "who thinks that pushing valves straight down is actually unnatural, and who is therefore glad that our soft finger pads automatically adjust for lateral movements" Denney