[SML] SawStop

[Matt]

Thomas,

SawStop sent me an additional list as follows:

Other sources of 

 Metal sheeting such as Aluminum or copper

 Grounded metal (i.e. the blade guard splitter, the riving knife, a metal jig, or a metal tape measure

in contact with the table top.)

 Relatively large masses of ungrounded metal, such as a tape measure not in contact with the table

or a combination square or ruler)

 Foil-backed insulation

 Mirror-backed plastic (usually a metallic layer deposited onto the back of the plastic)

 Metallic paint layers (e.g. gold paint on picture frames)

Other conductive materials:

 Conductive laminate layers (some countertops have a foil layer behind the formica)

 Black melamine board that has carbon black in the melamine layer

 Carbon composite materials (helicopter blades, ski poles, fishing poles, tennis racquets)

 Electronic circuit boards (because of the conductive layers)

 Cell phones (you might think it’s listed here just for humor value, but a shop student actually did

run his cell phone into a saw to see what would happen)

 Uncured glue layers (wet glue is a good electrical simulator of a person)

 Wet pressure-treated materials (the metallic salt solutions use to treat the wood are quite

conductive unless very dry)

 Very wet wood (though usually the saw will try to shut down rather than activating the brake)

Basically you need to avoid cutting conductive materials. If you are in doubt about whether any material poses a risk of spuriously activating the brake, you can place the saw in bypass mode and make a test cut or two. If the material would have triggered the brake, the saw will blink its red LED (until the blade stops) to indicate that contact was detected. If there are no indications of detection, you can proceed to cut in normal mode. If detection is indicated, the material needs to be cut in bypass mode. When in doubt, test in bypass.

A side note: Nails and screws in and of themselves are not large enough to load the signal and cause an activation. However, if the operator or the table top is in direct contact with the other end of the nail or screw, a conductive path with be completed as if the blade contacted the person or grounded surface. Also, there is a small chance that in cutting through a nail or screw, a piece of debris could be carried by a blade tooth into the gap between the brake and blade. If the gap is bridged by conductive debris, then an activation can occur. 

Thank you,
Matt Evans
Technical Director
University of Dayton
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