Tools for Basic Layout

The procedure of making reference mark on the work-piece is known as layout. Laying out involves marking the circles, arcs, straight lines, center point, on the surface of the work-piece to point out the position of hole to be drilled and the amount of material to be eliminated by shaping or milling machine. These marks point out shape, size and features of the work-piece. Layout marks are frequently pointed out on the surface where machining will occur. Operator uses these marks like a guideline for machining during checking of work-piece with actual measurement. Work-piece may cut as per to layout mark. The layout should be made up from the base line or the machined edge to make sure the accuracy of the layout and correct position of dimensions with respect to each other. The accuracy of a finished job is usually determined by the amount of care taken when laying out.

The layout is extremely significant for cutting the stock, filing and offhand grinding, drilling, milling etc. One of the jobs of the operator is to compute and layout at the place, in which the stock will be cut. This sort of layout may be marked through pencil or chalk. Layout marked by pencil or chalk, is termed as semi-precision layout. Semi-precision layout is usually done by steel ruler that gives tolerance up to 0.5 mm. Precision layout can be complex and needs sophisticated tools for operation and usually done by tools that give tolerance up to 0.025 mm or finer. The reference points, plane, lines are pointed out by laser and optical instruments in aircraft and ship building industries.

Objectives

After completing this unit, you should be able to understand

• Several types of tools required for layout,
• The need for accurate layout, and
• The aim of layout tools like scriber, dividers, squares etc.