A list of objects with something in common

[gfish]

Pocketknife
Angle grinder (cut off disk)
Angle grinder (sparks)
Lathe gear teeth
Welding slag
Oven
Screwdriver
Pencil tip
Suturing needle
Soldering iron
Brother's fingernail
Hacksaw
Tree branch
Bicycle handlebar
Weed-wacker engine
Garden hose fastener
Gravel
Scalpel
Pavement
Glass