-------------------------------------------------- From: "RussellMc" Sent: Saturday, July 10, 2010 4:59 PM To: "Microcontroller discussion list - Public." Subject: Re: [TECH]:: Auto stop table saw - demo with real finger > I posited an upper feed rate of about 1 m/s or 1 mm/ms. I was wondering about these calculations. I don't know much about table saw terminology but I assume you mean the blade edge travels 1 metre per second or 1mm per millisecond? The reason I ask is that in the video it says the blade is travelling at 5000RPM. By my calculations (which may be way out) assuming a blade of 10in diameter = 31.4in circumference = 797mm. At 5000RPM that's 83.3 turns per second which is 83.3 * 0.797 = 66.38m/s. So roughly 6.6cm in 1ms or about 30 degrees. Am I missing something here? is a standard blade far smaller in diameter than 10in? With those calculations it seems the saw would have to stop quite a bit quicker than 1ms to avoid damage to finger. He does say it stops quicker than 1ms in the video, but not how much quicker. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist