Introduction to 3D Printing Inventor

Objective

This exercise will introduce Autodesk Inventor, which is drafting software that is used by technical professionals, and basic technical design methods will be shown using this computer-aided design (CAD) software. This software will be used in your semester-long design project by constructing physical prototypes with 3D printing.

To practice this prototyping procedure, an NYU logo keychain will be created in Autodesk Inventor and exported to be 3D printed. The members of the winning team of “Lab 1C: Mousetrap Vehicle Competition” will each receive a 3D-printed keychain.

Overview

Computer-Aided Design

CAD programs, which include Inventor, AutoCAD, Revit, SolidWorks, and SketchUp, allow engineers to make precisely scaled drawings. These drawings are used to manufacture equipment, build infrastructure, and allow designers to display their designs with complete specifications and detail. Orthographic views (top, bottom, side, front, back, etc.) can be used to document every aspect of the technical drawing needed for production while isometric views can be used to view the final 3D representation of a product.

This exercise will teach the basics of Autodesk Inventor, 3D file formats, and the basics of 3D printing. After this lab, you will be able to create simple 3D files and set them up to be 3D printed.

3D Printing

3D printing allows for rapid prototyping and onsite manufacturing of products. Initially done with plastic, 3D printing now uses new techniques with new materials, such as aluminum, bronze, and glass. Biomaterials are also being incorporated, such as 3D printing ear cartilage and liver tissue. As the 3D printing industry grows, 3D printing will become a big part of many engineering fields.

In this course, 3D printing can be used to produce SLDP course modifications, robot parts, and a team logo for extra credit.

Procedure

Setting up the file

1. Start AutoDesk Inventor and open a new file (Figure 1).

   

   Figure 1: Inventor Toolbar

2. Select the measurement system to be used (for this lab English) and select a standard (in).ipt file (Figure 2).

   

   Figure 2: Inventor new file options

Designing the NYU Keychain

Figure 3: Sketch 1 before trim

1. The first step to designing the keychain is to draw the base shape:

   1. Start 2D Sketch
   2. Select the XZ plane
   3. Rotate the camera to orient the top correctly
   4. Select the rectangle tool

      1. Draw a 2.6” x 0.7” rectangle starting at the origin
      2. These values can be typed in (switching which value is changed is done using the tab key)

   5. Select the circle tool

      

      Figure 4: Sketch 1 after trim

      1. Draw a 0.7” diameter circle centered in the middle of one of the short sides of the rectangle (the cursor should snap to the center position and turn green when you get close)
      2. Draw another circle 0.45” in diameter in the same position

   6. Fillet (round) sharp edges

      1. Select the fillet tool from the “Create” section of the toolbar
      2. Select one of the two intersecting lines that form the right angles on the base
      3. Use the default fillet size of 0.125” and repeat on the other corner
      4. The sketch should look like Figure 3

   7. Remove the extra lines using the trim tool

      1. Select the trim tool from the “Modify” section of the toolbar
      2. Select all interior lines that divide the keychain (Figure 5)
      3. If error messages are indicated, remove the dimensions on the rest of the keychain
      4. The sketch should look like Figure 4

   8. Exit the sketch using the finish sketch button

2. After creating a 2D sketch, the next step is to use that to create a 3D object. In this lab the extrude tool will be used to create a 3D block. In the future, the revolve or other tools can be used to create more advanced geometry.

   

   Figure 5: Sketch 1 extruded

   1. Select the “Extrude” tool from the “Create” section of the toolbar

      1. Select the profile of the object to be extruded, which is the object that was just created
      2. Change the extrusion thickness to 0.15” and press Enter.
      3. The model will look like Figure 5

3. The next step is to add the design to the key chain. For this lab, a vector graphics file will be used in the dxf format provided by NYU. In the future, a logo can be designed using the sketch tool

   1. Download the NYU Tandon Vector Logo (This logo was converted from the file provided on NYU's identity page)

      1. * Tandon logo ACAD format

   2. Select “Start 2D Sketch”
   3. Select the top surface of the key chain
   4. Rotate the camera again to orient the top correctly
   5. Select the “ACAD” option from the “Insert” toolbar

      

      Figure 6: Drawing import settings

      1. Select “Files of Type” .dxf and open the downloaded design (this may take a moment)
      2. Select “Next” on the “Layers and Objects Import Options” window
      3. Check the “Constrain End Points” and “Apply Geometric Constraints” boxes
      4. Select “Finish”
      5. Settings are shown in Figure 6
      6. If the computer freezes use the alt+tab hotkey to check if DWG trueviewer is reporting an error

   6. For this side of the key chain the “Tandon School of Engineering” portion of the logo is not needed

      1. Select the bar and everything to the right using click and drag
      2. Delete this portion with the “Delete” key on the keyboard (Not Backspace)

   7. The logo needs to be scaled to fit the key chain. To keep the spacing of the design, select an appropriate base point. Use the midpoint of the line on the right side of the box

      1. Use the line tool to trace over the line on the right side of the box
      2. Select the point tool under the create section of the toolbar
      3. Place a point at the center point of the line that was just drawn
      4. Select the “Scale” tool from the “Modify” section of the toolbar
      5. Select the box and torch of the logo by clicking and dragging

         

         Figure 7: Sketch 2 final

      6. Select the midpoint that was just placed as the base point for scaling
      7. Enter a scaling factor of 0.75

   8. The logo will be positioned on the keychain

      1. Select the entire logo and use the “Move” tool from the Modify section of the toolbar to move it off the base so there is space to draw the alignment line
      2. Select the line tool and draw a 0.7” line from the middle of the right side of the circle towards the center of the keychain
      3. Select the logo using the move tool again, this time making sure to use the midpoint created earlier as the basepoint.
      4. Place the basepoint at the end of the alignment line
      5. Exit the sketch
      6. The final sketch is shown in Figure 7

   9. To finish this side of the keychain, the design must be cut into the base. To do this, the extrude tool will be used

      

      Figure 8: Extrusion 2

      1. To cut the design, select “cut” in the shape menu.
      2. Select the profile of the design to cut, in this case, the area around the torch and each of the letters
      3. Select a depth of 0.06”
      4. The final model is shown in Figure 8

4. To 3D print the design, export the file as an STL. This is the only format that can be opened by the 3d printing software

   1. Before exporting, the units of the print has to be converted to milimeters from inches, since that is the more standard units for 3D printing softwares

      1. Click on the Tools tab > Options panel > Document Settings
      2. In the dialog box, click the Units tab
      3. Under length, select mm
      4. Click Apply to save changes

   2. Click the Inventor Logo in the top left
   3. Select “export” then “CAD format”
   4. Select .stl from the dropdown menu and name the file
   5. Before pressing save select options and select mm as the unit

      1. This ensures that the keychain remains to scale when imported into the printing software

   

   Figure 9: Inner fill box

5. The last step of the keychain is to make the white insert that will fit in the center to make it two colors

   1. Click “My Home” in the bottom file tabs
   2. Start a new file
   3. Create a rectangle with dimensions 2.2”x0.65”
   4. Extrude the rectangle 0.12”

      1. This model is shown in Figure 9

   5. Export this in the same way as before

      1. Make sure to reselect units again

Preparing to print

Figure 10: Makerbot_1

Figure 10: Makerbot_2

1. Now that the logo is designed, the next step is to put it together in the 3d printing slicer software. This software is used for orienting the parts on the printer and selecting the color of each object. It also generates the toolpaths that the printer will follow to print the objects. The software used in EG is MakerBot Desktop

   1. Open the software and select “add file.” Open the stl containing the base of the key chain
   2. Using the rotation tool, orient the part so that the torch is facing up
   3. Press lay flat in the translation tab to move the keychain down onto the bed

      1. This step is very important to make sure the print starts smoothly on the bed

   4. Select add file again, open the filler rectangle
   5. Orient the part correctly using the rotation tool
   6. To vertically align the part, open the translation tool and type in 0.15mm as the Z value
   7. Horizontal alignment can be done by eye
   8. Select one piece and change the extruder under the info button

      1. If the info button does not appear, change the device type to Replicator Dual (under Devices > Device type)

   9. Save the file as a .thing (under file > save)

Assignment

A *.thing file must be submitted to eg.poly.edu. It is required for a lab report grade.