Discover the process of building a lampshade arm component using sketch constraints and extrude commands. This comprehensive guide walks you through the steps of creating a nested component, sketching, and dimensioning to construct the lampshade arm for a lamp assembly.
Key Insights
- The first stage involves activating the arm assembly component and creating a nested component within it named 'lampshade arm'. This sets the foundation for the sketching and construction of the actual lampshade arm.
- An integral part of this process is sketching with the use of constraints. Sketch constraints help in maintaining the relations between sketch geometries, making the sketch more precise and cleaner. The constraints are applied and manipulated until the desired shape is achieved.
- The final part of the process involves dimensioning the sketch, which helps in identifying areas where the sketch isn't constrained correctly. Once the sketch is completed and locked into place with the fix-unfix constraint, the component can then be saved for further modification such as extrusion and hole creation in the next stage.
In this video, we will build our lampshade arm component. I will open up Step 03, and when my file is open, I will close the data panel.
You will see that this file looks exactly like we ended the last video, with our arm assembly component already created. Because I am creating a component that I know will be part of my arm assembly, I will first activate my arm assembly component, then right-click > New Component to create a nested component. I will rename this Lampshade Arm and hit ENTER.
For this arm, I would like to look more closely at sketching and using Sketch constraints, and then creating separate bodies with separate Extrude commands. So, let's move over to the side and create our sketch in this area. I will click Create Sketch, place my sketch on the bottom plane, and again I will move over so I can see this area.
I could make this shape out of five rectangles, but I would like to explore more Sketch constraints. So to start, let's go to the line tool. I will zoom in and draw my first line about 15 millimeters long, just so I have a sense of scale, and I will begin to draw the rest of my shape. Notice I am not trying to make this exact, because I want to clean up my shape with Sketch constraints.
When I close my sketch, it will automatically create my profile. Now this sketch does not look very clean, and it has already placed some Sketch constraints around my sketch. If you have more or fewer constraints already applied, that’s okay.
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We will delete them all now. I will go to my selection, then to Selection Filters, uncheck Select All, and select Sketch Constraints. Now I can select all of my constraints with a crossing window and hit Delete.
I will go back to Select > Selection Filters and recheck Select All. Now I can begin to apply my constraints. The first constraint I will apply will be the Collinear constraint.
This places two lines collinear to each other. I will select the top two lines here and here, these three here and here, and here and here. Before we move any further, I will drag this down to retain my shape, and I will place one more at the bottom—here and here. Now I will begin to place Horizontal/Vertical constraints.
When clicking on a line, I can apply exact Horizontal/Vertical constraints without selecting two geometries. Now that all of my lines are horizontal, I could place Vertical constraints, but instead let's use the Perpendicular constraint. The Perpendicular constraint is applied between two geometries, so I will need to select a vertical line first and then a horizontal line to apply the constraint.
Again, as your geometry jumps around the screen, keep dragging it back into position to keep your sketch well organized. Before we move any further with dimensioning this sketch, I would like to split these regions into five rectangles. So I will drag it back into a rough approximation of my shape and draw some additional lines.
Let's go to the line tool, and I will draw a line from here to here. This line will only slide exactly up and down in this shape because I snapped it with a Coincident constraint at each point. I can place a Collinear constraint here and here, and now my line will move with this line.
Let's do that one more time, but this time I will purposely miss and draw my line out into space. I can apply a Coincident constraint to the line. Now my geometry has disappeared, but I know that it is still on the screen.
I will do a Zoom Extents, and there's my geometry. The Coincident constraint snaps to line extensions as well as the line itself. So let's go Perpendicular and select my line to snap it back into place.
I can now apply a Collinear constraint from here to here. This process is easier when I draw a line from endpoint to endpoint. If I go to the line tool and draw from this endpoint to this endpoint, it will automatically snap those lines in place, and it won't allow me to move them independently.
Now we can begin to dimension our sketch. I will press D for Dimension, and I will make this 15. I will make this one 15 as well, and I will do the same for these bottom ends.
I also want to dimension this edge as 15. I don't see a dimension from here to here, so I will go from this line to this line and make that 15. Then I will make these 30,30, and 30.
Now I can see that I have missed a constraint in my sketch. Dimensions help us identify where the sketch is not fully constrained. Finally, let's place a few more dimensions.
This will be 45, and the inside edge here will be 70. Now if I move my sketch around, we can see that it is not allowing individual lines to move, but the sketch is moving as a whole. I don't have specific geometry that I would like my sketch to snap to, but I can use the Fix/Unfix constraint to lock it into place.
So I will grab all of my sketch geometry and hit Fix/Unfix. This will turn my lines and points green and will not allow me to move them anymore. So I will click Stop Sketch.
Let's go ahead and hit the Home icon to generate our Home view and save the file. In the next video, we will extrude our lampshade arm geometry and create holes for our arm. I’ll see you in the next video.
