-------------------------------------------------- From: "Olin Lathrop" Sent: Monday, July 12, 2010 7:39 PM To: "Microcontroller discussion list - Public." Subject: Re: [TECH]:: Auto stop table saw - demo with real finger > One of the ideas I had I don't remember you mentioning (although I > admittedly didn't read much of your original message) is in part using the > blade's own momentum to move it out of the way. Table saw blades always > spin so that the top of the blade is moving towards the front of the saw > (apposing the direction of feed). Therefore a brake applied behind the > rotation axis would simultaneously slow the blade down while also > converting > the blade's rotary momentum into downward translation. That would require > a > mechanism to allow the blade to move downward while the brake is applied > at > the same time. Harnessing the momentum or energy stored in the rotating > blade should require less external energy input, and probably be less > stressful on the various mechanisms. I think (from watching the video Russell posted) that the Saw Stop does utilise the blades momentum in the way you describe, so it effectively "pulls" itself out of the way as well as stopping quickly. Not sure how this idea easily translates to the "pop back without damaging blade" idea though, unless you had some drive attachment that snapped into place (on a flywheel or something) and used the momentum to do similar. Consistency would be an issue here though, as it would depend on speed/weight etc, and unlike the Saw Stop this is the main safety function so I suppose you would need it to be as reliable as possible. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist