Solidworks Lego Power Digger

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Transcript of Solidworks Lego Power Digger

  • Project 1: L








    Lego Power

    my Gilliam

    hael Lagalle

    an Naghitor

    rian Neyra




    r Digger




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    I. Introduction The focus of this project was to model a robot arm mechanism, such that it moved in all three dimensions. The program Solid Works was used to create the part models and main assembly. The model created was of a commercially available Lego set meeting the specifications of the project called the Power Digger [1]. The final assembly consisted of four sub-assemblies and 32 different parts. Dimensions were taken using calipers along with other online resources [2] [3] in order to replicate each of the parts the solid model. Each part was individually created and then combined into the sub-assemblies, which in turn were combined into the larger main assembly. This report details the steps in order to recreate those parts in the Mechanical Design section along with the sub-assemblies. The model analysis will discuss the mass properties and results. An explanation on how to apply mechanism to the assembly will be discussed in the Kinematics sections. The project has given increased practice using the design features of the software and different techniques to create models for the final product. II. Mechanical Design: Parts 1. 368026 Turn Plate 2x2, Lower Part The Turn Plate is an important piece because it is what connects the body to the wheels and gives it rotation. It starts with an extrusion of a square, followed by various cuts and boss extrusions to give it shape. The center of the part has a hole in order to attach the upper part of the Turn Plate. The completed part is displayed in Figure 1.

    Figure 1. Turn Plate 2x2, Lower Part

    2. 4515340 Plate 1x2 W/Fork, Vertical The base of this part is simple. It was extruded from a sketch of a rectangle. The two first knob was created from a sketch of a circle then extruded. The linear pattern tool was used to create the second knob. Then, from the front plane of the brick, a sketch was created and extruded to make the forks. From that extrusion the two forks were cut out. In order to make the thread on the fork, a simple cut was made on the end, and then the circular pattern tool was used to repeat the cut along the edge. Lastly, a circle was extruded then filleted in-between the two forks to give it a place holder. The part is displayed in Figure 2.

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    Figure 2. Plate 1x2 W/Fork

    3. 4515368 Plate 1x2 W/ Shaft R3.2 The plate with shaft was created with a simple sketch of its side view and extruded out. The first knob was sketched on the top face of this model. It was then extruded up and patterned to create the second knob. The shaft was created by making a simple rectangular sketch and using the revolved cut feature around a specified reference line in the initial sketch. The bottom was then hollowed using extrude cut, to allow knobs of other parts to be inserted for assembly. This piece is a key piece in the Arm Assembly as without it the movement would be far more limited. The final piece is shown in Figure 3.

    Figure 3. Plate 1x2 W/ Shaft R3.2

    4. 4517925 Plate 1x1 W/ Holder Vertical The base of the holder was created with a simple sketch of a square that was extruded up. The knob was centered using the origin. It was then hollowed using the extrude cut feature. The holder itself was created by sketching in the yc-zc plane. It used the tangent constraints to keep a smooth surface, and the vertical constraint to have both tips stay lined up. The curves were created with a 3-point arc and then an offset. It was extruded from its mid-plane to keep it centered with the base. This component is used in conjunction with the shaft to allow rotational movement in the yc-zc plane. The final component is shown in Figure 4.

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    Figure 4. Plate 1x1 W/ Holder Vertical

    5. 4535739 Plate 2x1 W/Holder, Vertical The Plate 2x1 W/Holder component was constructed by creating a sketch of the bottom portion of the piece consisting of two nested rectangles spaced by 1.6mm and extruded up 1.6mm from the sketch plane. A reference plane was created on top of this extrusion, on which was drawn a sketch of another rectangle identical in size and location to the outer rectangle of the bottom layer, which was also extruded up 1.6mm. Once again, a reference plane was placed on top of this extrusion. Then, a sketch was created for the knobs on the top of the Lego, consisting of two circles evenly spaced across the surface, and this too was extruded up 1.6mm. The reference plane to create the holder was created next by spacing out from the side of the Lego by 2mm. The holder piece was created utilizing two concentric circular arcs with rectangular protrusions outwards, with the center of the arcs was located at a height of 2.4mm, determined by reverse engineering from a piece designed to fit into the holder. The edges of the holder piece protrude past the theoretical "bottom" and "top" of the piece. This sketch was extruded to a depth of 4mm, centering it on the piece. Finally, the bottom details allowing the piece to nest comfortably with the other Legos were added in. A sketch on the plane at the top surface of the first extrusion (that is, the surface also representing the bottom of the Lego's "ceiling") containing two evenly spaced circles for the holes underneath the pegs was created first, and the Extruded Cut tool was used to cut through the existing extrusion by 1.6mm to hollow out the pegs. The final step was to create the "donut" shape in the middle, which was accomplished through a sketch of two nested circles extruded to 1.6mm, bringing them to the same depth as the sides of the Lego. The final product is shown in isometric view in Figure 5.1, and the bottom is shown in Figure 5.2.

    Figure 5.1. Plate 2x1 W/Holder final product, isometric view

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    Figure 5.2. Plate 2x1 W/Holder final product, underside

    6. 403226 Plate 2x2 Round The Plate 2x2 Round was created by first extruding a circular boss from the Top Plane. Next, two circles were extruded on the top face and were mirrored about the Front Plane. These four extrusions formed the Lego studs. The next steps were to extrude a circular cut along the outside perimeter and extrude a square cut up from the bottom face. Finally, a plus-shaped extruded cut was made in the center of the top face and a ring was extruded from the underside of the top face up to the bottom face. These can be seen in Figure 6.

    Figure 6. Plate 2x2 Round

    7. 614126 Round Plate 1x1 The Round Plate was mostly likely the simplest design piece in the project. It was made from three circular boss extrusions, concentric around the origin. A hole was made at the bottom using an extruded cut. The part is displayed in Figure 7.

    Figure 7. Round Plate 1x1

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    8. 4617848 Tyre R17, 6x6, 24 The Tyre was created by first extruding a circular boss from the Front Plane. Then, a circle offset from the perimeter was cut through all to form the ring shape. Next, a single tread was added and subsequently patterned 360 degrees around the tire, with equal spacing. The same shape cut and pattern were then created on the opposite side of the tire; however they had an angular offset of nine degrees. Finally, the inner geometry was created by revolving a trapezoidal sketch 360 degrees along the inside. These can be seen in Figure 8.

    Figure 8. Tyre

    9. 615726 Bearing Element 2x2 2/3 This model was created with a simple outlined sketch that was extruded up. A single knob was sketched, extruded and patterned. The inner sides were sketched and a second extrude was applied. The single shaft was sketched and extruded on the side of the model. This feature was then mirrored. The center circle was sketched using the origin, and cut with the extrude cut feature. The bottom of the model had bracing that was sketched and extruded out of the model, which later had a chamfer applied to the four edges to keep a smooth design. This bearing element is an important model that serves as an axle within the assembly. The tires will be attached to here. The bearing will also serve as a foundation of the entire assembly. This can be seen in Figure 9.

    Figure 9. Bearing Element 2x2

    10. 6029947 Plate w. Bow 1x2x2/3 The plate with bow was created starting with a simple sketch of its side view, which was then extruded out. The two bottom faces then had simple square sketches extrude cut into the model, to allow space for knobs of other parts during assembly. This part is to connect two edges

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    at different heights and serves as a cosmetic edge piece, removing some of the innate blocky design of Legos. This can be seen in Figure 10.

    Figure 10. Plate w. Bow 1x2x2/3

    11. 4504381 Roof Tile 1x1x2/3, Abs The roof tile piece serves as an edge along the sides of the main sub-assembly. The overall shape was created by first sketching a trapezoid to form one side on the xc-yc plane, then extruding it 8mm perpendicular to the sketch plane. A shell tool with a thickness of 1.2mm created the walls. The last step was adding a Cut Extrude to take away the edges at the bottom. The final model can be seen in isometric view in Figure 11a, and from below in Figure 11b.

    Figure 11a. Roof Tile 1x1, isometric view

    Figure 11b. Roof Tile 1x1, underside

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    12. 4550348 Roof Tile 1x2x2/3, Abs This model was created from the base model in Step 11, the 1x1 roof tile, with the extrusion of the trapezoid changed to 16mm. A donut shape in the center was added by drawing a sketch of two concentric circles on the bott