Fret saw
A fret saw is a hand saw with a deep frame and very narrow blade. It cuts patterns in thin wood or metal sheets. The frame provides clearance around the work while the narrow blade suits fine contours. It belongs among tools used for school craft, decorative work and small handmade objects.
Store norske leksikon gives a characteristic blade width of 0.5 to 2 mm. This describes the tool type rather than guaranteeing the dimensions of every example. An electric scroll saw is a different construction; this article concerns the hand-held frame saw.
When examining an older saw, record frame, handle and blade fittings. Check whether components fit together and whether the frame is distorted. A replacement blade is a consumable part and cannot alone date the frame. Wear or darkened wood also cannot establish a particular age or manufacturer.