macdan Apple Pro Mouse variable spring tension mechanism I was so impressed with this wee bit of design I had to make this here wee page. If you already have a Pro Mouse apart (or intend to take it apart), why doncha take a moment to puzzle out for yourself how the variable-tension springing function works. Hmm, actually I can see the mechanism's 'secret' on an assembled PM . . . it's just harder to figger though than when it's apart. I've included some anti-spoiler space here: . . . . . . . . . . . . . . . . . OK, give up? Then hit this shortcut . . . otherwise . . . stop scrolling down if you don't want to miss the enjoyment of figuring it out for yourself! . . . . . . . . . . . . . . . Need a clue? Think 'spring length'. . . . . . . . . . . . . . . . . . 'K then, here's how it works: The spring has three effective fulcrum points. Turning the tension dial changes which of the fulcrum points is used. The two stiffer points press against tabs built into the tension dial which are moved into and out of position as the dial is rotated. The lightest setting '-' places the fulcrum near the spring's anchor point under your palm, so it uses the full length of the spring. The middle setting marked 'o' uses the fulcrum tab just at the rear of the tension dial when turned to that position. The stiffest setting '+' uses the forward most fulcrum at the front of the tension dial, which is of course the shortest of the springs and therefore the stiffest. Pretty damn cool IMNSHO. :-)

This image shows the points being rotated from light to medium to hard. I apologize as the bumps are really hard to see in these images but they were a bitch to photograph.

I hope whichever of Apple's industrial designer(s) thought this up got a big bonus for their ingenuity.

Hey, sorry for the spoiler-prevention, I realize it's annoying when you just want to read the damn 'solution' but I figured anyone reading this page is probably a die-hard hardware geek (errr, like me :-) who would like to figger this stoof out fer themselves.

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2004.02.13 - original page