PC touch screen, IPod and Sawstop

[Walt Nicholson]

I know (roll eyes) another SS question! My fingers (especially the index ones) are old, dry and calloused from too many years of use. When I try to operate a PC touch screen or an IPod touch screen with them nothing happens unless I lick them first to add a little moisture. If I use one of my other fingers (less calloused) things work fine. Is this the same technology used by the SS or is it a different principle? I assume the blade would fire once it got in past the calloused part but was just curious if anyone knew if it was the same technology.

[Karl Brogger]

Different deal. The Sawstop sends a current through the blade, when your skin touches it, you complete the circuit. Even the roughest of skin has some nice moist stuff just below the surface that will do the job, and it'd probably just be a nick.

I have to do the same things with touch screens, and the iPods. The touch screen in both of my pickups, and my phone respond best to a fingernail, where as I have to use the finger lick trick with touchwheel on an iPod. I think the iPod has something to do with heat, where as the touchscreens respond to pressure. Using a stylus pen, you definetly aren't completing anything.

[Mr. Jeff Smith]

You are fine Walt, the SS should still work as advertised.

Karl, the Ipod etc uses a capacitive touch screen which are generally more expensive, but work on a prinicple not to different than what SS is doing. (Albeit a much different level)

The screen in your truck sounds like a resistive screen sense you can use your fingernail. They work independent of any "electrical transfer" from the user to the screen and rely solely on pressure. So resistive is cheaper, more robust, but less accurate generally.

More info:
http://en.wikipedia.org/wiki/Touchscreen

[Will Overton]

Walt,

This may be another SawStop thread, but it's the first original question I've seen in quite awhile.

While the responses above are probably correct, I'd like to see you pose the question to SawStop and post their response.

[Steve Kohn]

There are touch screens now available that are a combination of both capacitive and resistive sense. This way they can sense both the human body model or a stylus/fingernail.

I don't have a clue about the sawstop part of the question.

[Victor Robinson]

I wonder if callus is as conductive as non-callus? It's one of those completely moot (as far as SS detection goes) but interesting subtleties...

[Brad Townsend]

Not to hijack the thread, but if I ran my iPod Touch through a Sawstop (which at times, I am tempted to do), would they cancel each other out?

[Victor Robinson]

After extensive scientific testing on my Sawstop, I can report that the system in fact does not detect contact on callus as it does on non-callus. Thus we can conclude that the conductivities of callus and non-callus are different. I suppose this also means that you'll get a deeper cut contacting the spinning blade if it's a callused part of your hand. And if your hand is just one giant callus, then you might be out of luck. Sorry if that sounded callous. How many times can I say callus?

This also applies to touchscreens (iPhone, iPad, iPod Touch), which are capacitive and therefore require the conductive touch of human body to use. However, I believe they are tuned to detect the conductivity of skin, which is why you can't use metal, etc.

[Van Huskey]

After extensive scientific testing on my Sawstop, I can report that the system in fact does not detect contact on callus as it does on non-callus. Thus we can conclude that the conductivities of callus and non-callus are different. I suppose this also means that you'll get a deeper cut contacting the spinning blade if it's a callused part of your hand. And if your hand is just one giant callus, then you might be out of luck. Sorry if that sounded callous. How many times can I say callus?

This also applies to touchscreens (iPhone, iPad, iPod Touch), which are capacitive and therefore require the conductive touch of human body to use. However, I believe they are tuned to detect the conductivity of skin, which is why you can't use metal, etc.

I have seen this question posed and your supposition was the answer. It will cut a little deeper to get to the nice soft meat on someone with thick calloused fingers. Interesting question but just to be clear there will still only be minor injuries compared to the alternative.

[Mr. Jeff Smith]

I have seen this question posed and your supposition was the answer. It will cut a little deeper to get to the nice soft meat on someone with thick calloused fingers. Interesting question but just to be clear there will still only be minor injuries compared to the alternative.

Exactly. This is what I meant if it was not clear. The SS will work as advertised to protect you. You may however lose some of your callous.