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Comment by kemayo | Hacker News Reader

Never having used one of these before, is there anything (ideally conveniently built in) that you can use to know before you cut a particular material whether it'll trigger the stop? Touch it against the blade while it's not running and see whether an LED lights up, or similar?

(I think it's unambiguously a good thing to mandate, but I'd also prefer not to have to memorize a table of materials and their interactions with the stopping device...)

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There are LED indicator lights that flash red when it detects a current drop. When the blade is not moving, you can touch it with your finger to see. In theory you could do this with whatever material you're going to cut. If you're cutting metal, it's pretty obvious that you need to disable the brake system. Usually where it's iffy is pressure treated lumber. Sometimes it'll trigger, sometimes not. Really depends on the moisture content of the wood and that can vary greatly. "testing" by touching the material to the blade with your hands on it might or might not indicate that the brake would fire. The points you're contacting could just not be that wet.

Most cheap lumber I see these days has a lot of moisture in it, treated or not. I’m surprised this works at all for anything short of quite-nice stock.

Pressure treated wood is also soaked with copper azole, which I believe increases its conductivity.

If you manage to cut metal with a table saw, you are a much braver person than I am

Aluminum cuts just like wood on a table saw. I wouldn't recommend trying to cut hard metals.

With the right blade, I would think that is possible. When a piece of wood kicks back and hits me it leaves a bruise through the clothing I wear. If a piece of aluminum kicks back and hits me, I imagine it would be nearly fatal.

I've always just used a regular dull-ish wood blade... never died. Survivorship bias?

Iron and steel? Of course not, go get a cold saw for that. But it's no problem and very common to cut soft stuff like aluminum and copper on a table saw.

> Never having used one of these before, is there anything (ideally conveniently built in) that you can use to know before you cut a particular material whether it'll trigger the stop?

You use a $40 “wood moisture meter” to check the water content of the lumber before cutting. If you want a built-in one I suppose you could duct tape it to your saw.

https://www.kleintools.com/catalog/environmental-testers/pin...

What about some suggestions offered in good faith?

That is how you measure the moisture content of wood, with a wood moisture meter. There’s no reason for a handheld $40 tool (that any serious woodworker will already have on hand, and one that will likely fail at some point) to be built in to a multiple thousand dollar table saw.

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