MARKING-OUT INFORMATION SHEETS MEL02INF4436 v1.2 HEALTH & SAFETY REQUIREMENTS RECORDING REQUIREMENTS: Record the results of your work on Task Worksheet MEL02TWS01 v1.3 REFERENCES: This document relates in part to the requirements of Unit Standard 4436 v5

© Competenz - N Z Engineering Food & Manufacturing Industry Training Organisation Inc.

Dividers

Scriber Engineers Square

Center and Dot-Punches

Steel Rule

MARKING OUT

The purpose of marking-out is to; Define the shape of an article Indicate position of holes and other features Provide alignment and machining marks Minimize material wastage

Marking-out techniques include the use of datum, pitch circle diameters (PCD) and templates.

Marking-out is usually done on a firm, flat work surface or vertically using marking-out tools on a surface table.

Parallels

Tools Commonly Used for Marking-out Tasks

Combination Set

Marking-out Using Datums

Effective marking-out requires clean edges and faces on the work piece, and uses a combination of at least two primary reference points such as Datum Points, Datum Lines and Datum Edges.

Marking-out using datums can be done using either;

Simple hand tools such as a ruler, scriber, square and odd-leg calipers, or

Vertical marking-out tools such as an angle plate, scribing block or vernier height gauge situated on a marking-out table

Odd-leg calipers

Surface Table

Scribing Block

Vee Blocks

Height Gauge

SMART TIP! When finished, return the tool to its storage

box, tool cabinet or the marked place on the workshop shadow board.

Angle Plates

Page 1 of 3

Use a rule, scriber and square to mark the hole positions along the centerline working from the datum at one end of the bar.

Marking Hole Positions Along a Centerline

Brush a thin layer of marking blue onto the surface of the metal bar to highlight the lines.

Use odd-leg calipers to find and scribe the centerline along the bar using one edge as the datum.

Marking Hole Positions on a Pitch Circle Diameter (PCD)

Marking Shapes and Hole Positions Using Templates

Templates are commonly made of sheet metal, plastic and wood and shaped to represent the finished article. Templates can be simple geometric shapes or detailed profiles used for fabricating complex structures.

Hole positions in the template are marked on the work-piece surface using transfer punches.

Use a rule to re-check the marked position. Center punch the location of each hole ready for drilling.

Center punch the PCD center-point and use a pair of dividers to scribe the pitch circle. Trammels are required for scribing larger PCDs.

Use an engineers square and odd-leg calipers to mark the position of the PCD centerlines from the datum edges.

Calculate the hole positions and use dividers to step-out and scribe the positions around the PCD.

Recheck the scribed positions. If OK, center punch the location of each hole ready for drilling.

Use a scriber to mark-out the template profiles. Use transfer punches to mark the locations of the holes ready for drilling. Use a rule to re-check the profiles and hole positions.

Locate the template on the alignment marks. Clamp in place if necessary.

Use an a square, odd-leg calipers, a rule and a scriber to lay-out the template

HANDY HINT; templates are a useful time-saver when marking-out repetitive fabrication work.

HANDY HINT; to ensure clean marking out, check the caliper, divider and center punch tips are not worn or damaged. SMART TIP!

Hole positions on a PCD

can be calculated by;

dividing the circumference

of the PCD by the number

of holes or,

by using jig-boring

coordinate tables.

Marking-out On a Table Work requiring accuracy to within 0.15 mm can be done using a scribing block. Accuracy to within 0.02 mm can be achieved by using a vernier height gauge.

Marking-out Using a Combination Set

Marking-out Using Spirit Levels and Plumb-bobs

Plumb-lines provide a datum when positioning vertical components in larger structures.

When positioned vertically, the horizontal distance between the plumb-line and the vertical component will be the same at the top and the bottom.

Use a spirit-level to check and adjust the position of a horizontal structural component.

A protractor can be used to establish the correct angle of a horizontal beam in respect to a vertical component.

HANDY HINT; increasing the vertical distance between the measuring points on a vertical plumb-line will improve the accuracy of the setup.

Plumb-bob

Vee blocks are used to support and clamp round work pieces during marking out with a vernier height gauge. The round bar should be supported on the angled faces of the vee block.

A scriber and a combination try-square can be used for marking-out at 90º and 45º to a datum face.

A combination set center-finder is used for scribing intersecting lines to establish the center of a round bar or circular shape.

An angle plate can be used to hold larger work pieces while marking-out vertical distances using a vernier height gauge.

Smaller, less accurate marking-out can be done using a scribing block.

SMART TIP! Check the tool for any damage or faults such as worn, broken or missing parts, expired calibration or the tool not zeroing. Report any problems to your supervisor.

Use a scriber to mark the final position prior to riveting, bolting-up or welding.

Steel beam

A scriber and a combination set protractor can be used for marking-out virtually any angle from a datum face.

Check for a true right-angle using an Engineers Square or a Rafter Square.

The glass or plastic vial on a spirit level is usually marked in 1-degree increments. A small air bubble sits central to the vial when the level is placed on a horizontally true surface.

Flat and true machined surface.