<< Click to Display Table of Contents >> Navigation: Getting Started Tutorials - MechDesigner > Tutorial 4: From Sketch-Elements to Extrusions > Step 4.4: Level 2: Sketch-Loops and Extrusions in Parts |
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I have prepared this simple model. I have added a: 1.Line to the Base-Part 2.New Part 3.Pin-Joint between a Point in the Line in the Base-Part and a Point at the Origin of the new Part 4.Motion-Dimension FB The kinematic-chain is kinematically-defined - they are Green Parts. The Part is a Rocker. |
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STEP 1: Start the Part-Editor to edit the Part. 1.Double-click the Part-Outline. You can use the View toolbar > View Align tool to rotate the Part so that its X-axis is horizontal. I usually do not do 'View Align'. |
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STEP 2: Use the Part-Editor to add a 3 Lines and 3 Arcs For the purposes of this tutorial ONLY , do NOT merge the points as you add the sketch-elements. It is always faster to use the Merge-and-Hover technique as you add the sketch-elements. In this case, the image shows that the Arcs and Lines are not merged. |
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STEP 3: Click Geometry toolbar > Merge-Points tool 1.Click the two Points you want to merge Make sure Point 1 is red when you click the Point 2 2.Click the graphic-area to complete the command Merge-Point is not a persistent command Do the Merge-Point command six times to merge two Points size times. |
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STEP 4: Close the Part-Editor when the Sketch-Loop is complete. •In the Mechanism-Editor, the color of the sketch-loop is the same color of the Part-Outline in the Mechanism-Editor. This means the sketch-loop will be is Green because the Part-Outline is Green. |
In the Mechanism-Editor, select the Add Profile command. STEP 1: Add menu > Mechanism sub-menu > Solids sub-menu > Add Profile. In the graphic-area, select a Line or Arc that in the sketch-loop. |
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STEP 2: Make sure the sketch-element is in the Command-Manager MechDesigner will add the Profile only if the sketch-loop is 'valid'. That is, Points at the ends of the sketch-element are merged. ![]() Message in Feedback Area for 'Invalid Sketch-Loop' If the sketch-loop is not 'valid', MechDesigner does not add the sketch-element to the selection-box in the Command-Manager. In this case, see left for the message is in the Feedback Area. |
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STEP 3: Click The colors of the Profile element is Pink , which you see from the Front-View. You will not see the sketch-elements when the view is the Front View. |
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STEP 4: Click the Model name-tab. Spin the model, if necessary, to see the Extrusion that fills the gap between the Profile contours. You can click the left-right & up-down arrow-keys on your keyboard to spin the model.
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STEP 5: Click the Mechanism-Editor, and spin the View with the Arrow keys on your keyboard.
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You can see one of the two Profile contours. There are always two Profile contours – the Primary Contour and Secondary Contours. The Primary Contour and the Sketch-loop are at the same position. MechDesigner may show the sketch-elements in preference to the Profile. How do you edit the Profile contours? See 'next part to this step in this tutorial'. |
STEP 1: SHIFT+CLICK the Profile. Shift+Click a Profile in the graphic-area, to show in the Selection-Window: •Profile •Extrusion |
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![]() Selection-Window |
STEP 2A: Edit the Extrusion in the Selection-Window. 1.Right-click the Extrusion 2.Click Edit element from the contextual-menu, The Extrusion dialog-box opens. |
![]() Assembly-Tree |
STEP 2B: - or - 1.Right-Click the Extrusion in the Assembly-Tree, and 2.Click Edit Element in the menu The Extrusion dialog-box opens. |
Extrusion Parameters Three parameters control the position of the Profile relative to the Mechanism-Plane: Extrusion Depth specifies the distance to the Secondary-Contour from the Primary-Contour. This is always a positive value. The Secondary Contour is always 'in-front' of the Primary Contour. Extrusion Offset moves the Primary Contour along the Z-Axis of the Part. Part Offset moves the Primary Contours of ALL the Extrusions in a Part. The other parameters edit the Properties of the Extrusion. Show or Hide Extrusion, Extrusion color, Change Transparency, Graphic Quality Material Density MechDesigner calculates the Mass and Inertia from the Density, Profile Contour, and the Extrusion Depth parameters. |
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Extrusion Depth: •When you edit the Extrusion Depth, only the Secondary Contour moves along the Z-axis. In the image to the left: •Extrusion Depth is 10mm. •The Primary Contour is coincident with the sketch-loop. The sketch-loop may show in the graphic-area over the Profile. |
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STEP 1: Edit the Extrusion Depth. •I have edited the Extrusion Depth to 30mm with the spin-box tool. The Spin-Increment is 10, so it took two clicks! •The Secondary Contour moves away from the Primary Contour. The Primary Contour does not move when you edit the Extrusion Depth. Note: If the model is very large, the Extrusion Depth parameter can take a few seconds to update. |
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2.Extrusion Offset and Part Offset •There is only one Extrusion in this model. Therefore, comparison between Extrusion Offset and Part Offset is not immediately clear. •MechDesigner adds the Extrusion Offset and Part Offset. They calculate where the Primary contour is relative to the Mechanism-Plane. These values are Positive or Negative. •The Secondary contour always moves with the Primary contour. STEP 2: Edit the Extrusion Offset. •The Extrusion Offset is -10mm. •The Primary Contour moves from the Mechanism-Plane in a negative direction by 10mm. •The image to the left shows the new positions of the Primary and Secondary contours. |
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Part Offset: •A Part may have more than one Extrusion and it may be convenient to move all of the Extrusions together. •The Part Offset applies to all Extrusions in a Part •Add the Part Offset to the Extrusion Offset to equal the total offset of the Primary contour from the Mechanism-Plane. STEP 3: Edit the Part Offset •The Part Offset is 30mm •Add the Part Offset to the Extrusion Offset. The total offset is (-10+30) = 20mm from the Mechanism-Plane. |
STEP 1: Toggle IN Visibility toolbar >'Show Model Element in Mechanism' |
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STEP 2: First, edit the Extrusion again. Remember, to Edit an Extrusion: 1.Click the Profile in the graphic-area 2.Right-click the Extrusion in the Selection-Window 3.Click Edit element in the contextual-menu Enter these values in the Extrusion dialog-box: •Extrusion Depth = 10 •Extrusion Offset = 20 •Part Offset = 0 |
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STEP 3: Add a new Profile 1. In the Mechanism-Editor, Use the 2.In the graphic-area, select a Line or Arc from the same sketch-loop. 3.Click OK in the Command-Manager. |
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STEP 4: Edit the new Extrusion. 1.Click on the Profile in the graphic-area 2.Right-Click the Extrusion in the Selection-Window 3.Click 'Edit' Enter these values: •Extrusion Depth = 10 •Extrusion Offset = -30 •Part Offset = 0 |
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STEP 5: Look at the two extrusions with the 'Right View' •In the Mechanism-Editor, use the View > From Right menu option. •Note: To make the Extrusions symmetrical to the Mechanism-Plane: the Extrusion Offset of the Extrusion 'behind' the Mechanism-Plane must compensate by the Extrusion Depth (Part Offsets is zero). Experiment! •The Extrusion Depths are 10. •The Extrusion Offsets are 20 and -30 |
STEP 1: Edit the Part in the Part-Editor Double-click the Part-Outline, or a sketch-element, in the Part. |
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STEP 2: Add dimensions and constraints to the sketch so the sketch-elements become black I have added: •Tangent constraints between the Arcs and Lines •Coincident constraints between the center of the bottom two Arcs and the ends of the CAD-Line •Coincident constraint between top Arc and the vertical Y-axis •Equal constraints to the Arcs •Dimensioned the Arc and the distance to the center of the top Arc •Re-dimensioned the length of the CAD-Line |
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STEP 3: Review the Profiles Click the Visibility toolbar > Show Solids in Mechanism tool to hide the Extrusions You can see that the Profile contours and the Extrusions have also updated to the new shape of the sketch-loop. (For some reason, the Profile contours are 'White' in this image - they are usually Pink).
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STEP 4: Add New Sketch-Elements Here, I have added three Circles to the sketch. The Circles are: •equal in size •coincident with center-Point of the Arc. A Circle is the most basic shape of a sketch-loop. |
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STEP 5: Add three new Profiles with the three Circles Do the commands three more times. AS BEFORE: Select Add Profile, select the Sketch-loop (the Circle), and click OK in the Command-Manager. ALTERNATIVELY, try this new technique! 1.Hover above the sketch-loop so it becomes red – DO NOT click it 2.Right-Click 3.Click Add Profile from the contextual sensitive icon palette 4.Right-click to complete the command. (This is a keyboard shortcut for OK in the Command-Manager). |
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STEP 6: Edit the Three Extrusions Here, we want the three Circles to be 'posts' between the two plates. Edit each Extrusion, and enter these values in the Extrusion dialog-box •Extrusion Depth = 80 •Extrusion Offset = -40 •Part Offset = 0 •Extrusion color – here all a light grey. |
STEP 1: Edit the Part 1.Double-click the Part-Outline, or a sketch-element in the Part. |
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STEP 2: Add a Sketch-Loop that is the shape of the Hole: •See the new Sketch to the left •The sketch-loop that is the shape of the hole is 'inside' the sketch-loop used for the Profile. •Close the Part-Editor. |
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STEP 3: Add a Hole to each side 'plate' Use the In the Command-Manager: 1.Click a sketch-element on the sketch-loop intended to be the shape of the hole (an 'Arc' has the label 'Circle'). 2.Click the Profile with the Extrusion through which you want to cut the hole. 3.Click Do Steps 1-3 again for the other Extrusion |
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STEP 4: View Holes through Extrusions I have used the Display Filter to 'hide' Points. 1.With the Visibility toolbar > Show Solids in Mechanism Toggled OFF, it is possible to see: Sketch-loops (green) for the: •Primary Shape, the three Posts, and the Hole Profiles (white - but default color is Pink) •2 for the main shape, three for the posts, and the Hole Element (also white, usually Maroon |
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STEP 5: Solids the Extrusion in the Mechanism-Editor With the Visibility toolbar >Show Solids in Mechanisms Toggle ON it is possible to see: Extrusions: •2 Blue 'Plates' made from the one primary sketch-loop •3 Grey Posts/Pegs made from Circle sketch-loops •2 Holes derived from one sketch-loop |
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STEP 6: Click the Model name-tab to review the model in the Model-Editor MechDesigner uses six lights to improve the display of the model. STEP 7: Right-click the Model element that is at the top of the Model Assembly-Tree. The Model dialog-box opens. Click the Lighting tab Also, see: Visibility toolbar > Solid Display Mode tool to view in the Mechanism-Editors:
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