Program a machine that applies acid to precision-etch metal and plastic.
Casts and finishes plaster patterns used in making precision sand molds for dies, tools, and machine parts, according to specifications: Constructs boxlike enclosure around part to be cast, filling in cracks and openings with clay. Lubricates surface with parting agent that prevents plaster from sticking to part. Mixes plaster and pours it into enclosure. Reinforces plaster with hemp fiber and small steel rods or heavy wire. Removes hardened plaster cast from enclosure. Patches broken edges and fractures, using clay or plaster. Trims plaster pattern to tolerance by scraping and shaping plaster surfaces by hand following blueprint, using flat metal scrapers. Verifies dimensions, using measuring instruments, such as calipers, vernier gauge, and protractor. Makes identifying marks on pattern with crayon, inked rubber stamps, or pointed tool. Shellacs finished surfaces to harden and smooth them.