Tear bar
A drawing rail or drawing rail (also T-rail - because of the similarity with the letter "T") is a drawing device that is used in combination with a drawing board and drawing material. The tear bar helps you draw horizontal and parallel lines. It serves as a basis for set squares , Typometer , scales , rulers and templates that are applied to them to draw parallels and non-horizontal lines and positioning images with templates.
According to the "rules of the art", the T-rail is only "struck" on a vertical edge of the drawing board and all other directions are touched by triangles or angle templates. This ensures that a non-rectangular drawing board will lead to incorrect results. If the board is perfectly square, the rail can be attached on all sides.
Typical materials are wood and plastics, including metal (which allow cutting on the rail). The length is usually 50-70 cm, but can be significantly longer. Special tear rails are provided with an adjustable head part that enables the angles to be fixed.
Traditional T-rails usually have no divisions, as they are only used as a mooring option.
In the area of final drawings and the production of templates for offset printing , the tear bar was more popular than a drawing machine despite its simplicity , as it enables greater accuracy when creating a drawing.
Architectural draftsman applying angles to a tear strip (1954)
The picture of Caspar David Friedrich in his studio by Georg Friedrich Kersting with a tear strip in the background (Mannheim version from 1819).
Plastic sign rail with division (cutout), designation
