What type of screw ?

Some thread-forming screws are appropriate for use on either plastic or metal, depending on the specifics of the application.

*Generally* sheet metal screws are "pointy" and fasteners intended for plastic are blunt-nosed with a cutting notch on the end but there are many variations.

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Rich Webb     Norfolk, VA

"Rich Webb"

** Often thread forming screws for plastic are " twin tread " too.

A real time & motion expert's favourite.....

.... Phil

screws for plastic have a notch at the tip and a blunt tip. screws for sheetmetal have a point or a triangular cross-section screws for thicker steel (over 1mm) have the notch too but are made of hard steel.

there's a bunch of other thread-forming screws too (like for brick, and self-drilling for steel sheet )

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?? 100% natural