Marking out

Marking out

if the parts are not the right size
1. they will not fit together
to make an accurate product, you have to prepare the materials you are going to use
1. measuring and marking out where any machining operations are needed
Datum edge
1. provides a set reference point
  1. without a flat surface to work from, measurements will not be accurate
2. could also be side, face, from where the dimensions are measured
tolerance
1. the amount that a measurement can vary from the stated value and still be acceptable
which tool used depends on the required accuracy
1. rule: 0.5 mm tolerance
  1. steel or plastic
2. (digital) vernier calipers
  1. 0.02 mm
    1. sliding section over a steel bar, used to measure thickness or diameter of a part
3. micro-meter
  1. 0.1 mm
  2. tightens onto a piece of material using a screw mechanism
tools for marking out- lines that are to cut or processed on a piece of material
1. wood
  1. pencil
    1. or a marking knife
2. metal or
  1. plastic
    1. scriber
      1. can be used on very hard tool steel
      2. used like a pencil to scratch a mark in the material
      3. or ( for metal)
  2. punch
    1. made form very hard tool steel, which is hit with a hammer to make a mark on the metal
      1. dot punch- highlights lines, marks centre of circles
      2. centre puch- marks centre of hole to be drilled
drawing circles/ arcs
1. for wood: compass
2. for plastic/ metal: dividers
  1. similar to compass, but with two hard points, like a scriber, to scratch a line
try square
1. if the line is at 90 degrees top edge
2. wooden stock and a carbon steel blade
3. wood and plastic
4. engineer's square
  1. same purpose, but for metals
    1. metal stock and blade
angled lines
1. sliding (or adjustable) bevel
complex shapes
1. use a template
  1. paper/ card
check measurements again, after you have marked out
1. to ensure a mistake hasn't been made before the material becomes waste

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	Created by fampulli almost 11 years ago