Part Design

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Chapter 2

• Part Design
• Creating Sketch Based Feature
• Extrude Revolve

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2.0 Content Chapter 2

• What is sketch-based feature?
• Datum, axes, coordinate system
• Defining parts in Sketcher
• Sketcher tools
• Sketcher plane and sketcher references
• Adding or editing dimensions
• Sketcher geometric constraint
• From sketch to 3D Extrude
• From sketch to 3D Revolve
• Demo

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2.1 Part Design Sketch based feature

• All parts will be created from feature(s). Some
  part may have one, two, ten or more features.
• Sketch-based features that started off with a 2D
  sketch, and applied with 3D operation such as
  extrude or revolve.

Source PTC.com
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2.1 Datum, axes coordinate sys

• 3 datum planes and a coordinate system will be
  created automatically when starting a part
  drawing.
• Datums are point of reference for the software to
  calculate distances.
• Datums can be actual points, planes or curve but
  have no thickness.
• Very important and useful in part design and
  assembly.
• Datums may be created at any time.

Source PTC.com
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2.2 Defining parts in Sketcher

• Sketcher is used to create a 2D profile of a
  feature.
• The geometric shape will be defined in sketcher
  dimensions and constraint.
• In sketcher the profile is drawn in x and y
  dimensions, and given the depth in z after that.

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2.3 Sketcher tools

• The basic tool include line, circle and arc
  creation command located on the right hand side
  toolbar.
• More commands are available by clicking the small
  triangle on the right of the icons.

Source PTC.com
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2.3 Sketcher tools Sketch plane

• Sketching plane is the first thing to identify
  when setting up a sketch.
• This is the surface on which you will draw. A
  sketching plane can be a surface of an existing
  part, or it can be a datum plane.
• Sketching plane should be flat, not curve
  surface.
• The selected plane or surface is rotated flat to
  the screen in Sketcher.

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2.3 Sketcher tools Sketcher reference

• After the sketching plane is established,
  Sketcher requires existing planes and edges from
  which to dimension the new section.
• By default, Sketcher automatically selects two
  reference planes or edges, a horizontal and a
  vertical, to start a sketch.
• As you add to the sketch, you may need to add
  more references.

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2.3 Sketcher tools

• When the screen is rotated to 2D, you may used
  the available command to produce the 2D profile.

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2.3 Sketcher tools Dimensions

• When the sketched outline is finished, it is
  dimensioned with default, weak dimensions. These
  dimensions are added automatically by Sketcher
  when you sketch. They are displayed as gray
  lines.
• To enter strong values for a single dimension in
  Sketcher, click the weak dimensional value and
  type directly into the textbox. The dimension
  becomes a strong dimension, shown in normal
  linewidth, and the line or angle is adjusted to
  the new value.

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2.3 Sketcher tools Dimensions

• If Sketcher has not provided a dimension or angle
  that you want, use the Add Dimension command on
  the Sketcher toolbar to add one, and then enter a
  value for it.

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2.3 Sketcher tools Sketcher geometric constraint

• Constraints work with dimensions to define a
  section. A constraint states that one line has a
  definite geometric relationship to another.
• For example, if you want a line in your new
  section to be parallel to and equal in length to
  an existing line, you can add those two
  constraints to the line in the section, rather
  than entering new dimensions.

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2.3 Sketcher tools Sketcher geometric constraint

• Constraints are represented by small symbols on
  the constrained line. In the figure, the radius
  of the right circle is constrained to be the same
  as the radius of the left circle.
• The two center points are constrained to be
  equidistant from a centerline. Thus, you need
  only dimension the original, left circle. The
  right one will mirror it automatically.

Source PTC.com
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2.4 From sketch to 3D Extrude

• When a Sketcher section gains depth, or a
  z-dimension, it becomes a 3D geometric entity
  called an extrusion.
• The extrusion may add or remove material. It can
  be a solid, or it can be a cut.
• Extrusions can be defined in several ways. For
  example, both protrusions and cuts can be
  extruded, with depth added directly to a section.

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2.5 From sketch to 3D Revolve

• Revolve enable the 3D solid to be created from
  the sketch by rotating around a defined axis.

Source PTC.com
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2.6 Demo Step-by-step extrude
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Sketch-based feature extrude
Sketch
Extrude Protrusion
Extrude Cut
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Extrude example
3 FEATURES
? EXTRUDE
? EXTRUDECUT
? EXTRUDECUT
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2.6 Demo Step-by-step revolve
360 degree
2D SKETCH
REVOLVED PART
270 degree
180 degree
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Revolve example
EXTRUDE 1ST FEATURE
REVOLVE 360?
SKETCH
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Revolve Cut
COUNTERSINK HOLE
SKETCH ON MIDPLANE
REVOLVE 360 REMOVE MATL.
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Revolve example
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End of Chapter 2