page 1 of 3 marking-out information sheets …tool… · simple hand tools such as a ruler,...
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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
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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.