pinfeed

A pinfeed printer is a dot matrix printer that advances continuous-form paper using sprockets or feed pins that engage the perforated edges, or chad strips, that run along both sides of the sheet. The pins sit on a rotating drum or belt inside the printer and pull the paper forward in precise increments, typically 1/6 inch per line at standard 6 lines per inch vertical spacing. This mechanism allows the printer to maintain exact registration between the print head and the paper, essential for multi-part forms and pre-printed stationery.

The perforated edges contain a series of rectangular holes spaced 0.5 inches apart. The feed pins on the printer engage these holes and lock the paper in place laterally while advancing it vertically. This positive feed system was superior to friction feed methods because it eliminated skew and slippage, especially critical when printing on multi-part carbonless forms or when precision alignment with pre-printed guides was required. The paper typically comes on a continuous roll and can be separated into individual sheets by tearing along perforation lines after printing.

Paper and wear considerations

Pinfeed paper comes in widths from 8.5 inches up to 15 inches or more, with the chad strips adding approximately 0.5 inches to each side. Over time, the holes can tear or become enlarged from repeated engagement with the feed pins, causing the paper to slip or jam. Worn feed pins themselves become the other failure point; they flatten or break, reducing grip and resulting in paper advance errors. Both conditions degrade print quality by introducing misalignment between successive lines.

The term pinfeed distinguishes these printers from friction-feed or tractor-feed designs. Tractor feed, which uses more aggressive metal claws on adjustable bars, offered flexibility for different paper widths but could damage thinner stock. The pinfeed design occupied middle ground: reliable enough for standard business forms, gentler than tractors, and more economical than sprocket systems used in high-speed production presses. By the 1980s and 1990s, when dot matrix dominated office printing, pinfeed was the default for shops running volume form work.

Pinfeed printers declined sharply after 2000 as thermal, inkjet, and laser technologies supplanted dot matrix for nearly all applications. However, certain industries with legacy systems still operate them, and the mechanical simplicity of the feed mechanism means older units remain serviceable. The perforated paper edge, while often considered waste and discarded, is integral to the whole system and cannot be removed without losing the precision that made pinfeed attractive in the first place.