• Keyboard Case and Plate STL Generator With Automatic Model Segmentation
• How it Works
• Setup
  • Requirements
  • Usage
  • Parameters
• Example Output
  • Output Format
  • Small Layout Test
  • Full Size ANSI
• Printed Part
• Acknowledgements

Keyboard Case and Plate STL Generator With Automatic Model Segmentation

This is meant to generate a scad and or stl file from a keyboard-layout-editor layout file.

Additionally the model can be automatically segmented so that the parts will fit within the build area of your 3d printer

How it Works

The program takes a keyboard-layout-editor json file as one of the inputs along with an optional parameter json file to customize other parts of the resulting model

The program can then genarate a number of different items. The entire case can be generated as a single model or the case can be broken up so that parts will fit within the build size of your 3d printer. The build size is one of the values that can be places in the optional parameters file.

Setup

Requirements

• Python: Python is required to run the program. This was built using Python 3.8.10 but I expect newer versions should work fine

• SolidPython: This program relies on SolidPython to generate the actual OpenSCAD script. To install SolidPython you can most likely use the command bellow

  pip install solidpython
  

• OpenSCAD: In order to render STL files you will have to have OpenSCAD installed and the OpenSCAD executable must be on your path. OpenSCAD downloads can be found here https://openscad.org/downloads.html

Usage

• Here is an examle of the program cli usage

• Basic usage

  python keyboard_stl_generator.py -i layout_filename.json
  

  This will generate the entire case as one peice. IT will generate top, bottom, plate, and all scad files

• -f option: This option defines the number of faces that will be used when rendering a circle. I suggest using at least 32

• -a option: This will generate models for all of the separate model sections based on the 3d printer build plate size

• -e option: This generates a potentially useful exploded view where all sectons are in one model but the are separated tso they can be seen mroe easily

• -s option: This is used to generate just the model for a specific section

Parameters

• This is an example of a simple parameters file parameters.json
• Here is a list of the possible paramters and what they do

  • 3d Printer Relate Paramters

    • x_build_size: X build plate size in mm
    • y_build_size: Y build plate size in mm
    • kerf: kerf to allow for expansion of material usefuly to give switch holes a bit more space to fit better

  • Switch and Stabilizer Parameters

    • switch_type: Switch type. Default: mx_openable. Options: mx_openable, mx, mx_alps, alps, custom (requires custom shape parameters)
    • stabilizer_type: Stabilizer type. Default: cherry_costar. Options: cherry_costar, cherry, costar, alps
    • custom_switch: Defines the parameters for a custom switch shape. If this is defined it overrides the switch_type selection
      • points: List of x, y coordinates. The coordinates must be defined where (0, 0) is the center of the cutout shape. ex. This would be a 14x14 mm square [[7, 7], [7, -7], [-7, -7], [-7, 7]]
      • path: List that defines the order that the points should be traversed to draw the shape. If this is omitted the list of points will be followed in the order the are defined
      • EXAMPLE: The following example would create a 14x14 mm square cutout

        "custom_switch": {
            "points": [
                [7, 7],
                [7, -7],
                [-7, -7],
                [-7, 7]
            ],
            "path": [0, 1, 2, 3]
        }
        

  • Plate Only parameters

    • plate_supports: Generate support ridges that help to strengthen the plate true or false
    • support_bar_height: How far down from the top of the plate the support bars should be in mm
    • support_bar_width: How wide the support bars should be in mm

  • Plate and Body Parameters

    • plate_thickness: How thick the plate should be. This will affect how well switched hold into the plate in mm
    • top_margin: amount of extra material that should be added to top of plate in mm
    • bottom_margin: amount of extra material that should be added to bottom of plate in mm
    • left_margin: amount of extra material that should be added to left of plate in mm
    • right_margin: amount of extra material that should be added to right of plate in mm
    • case_height: the height of the case. When tilt is used this will be height of the lowest part of the case in mm
    • plate_wall_thickness: How thick the walls of the case should be in mm
    • plate_corner_radius: The radius to be used in rounding corners of the case in mm
    • bottom_cover_thickness: The thickness of the base palte of the case in mm
    • tilt: The number of degrees the case should be tilted forward

  • Mounting Screw Parameters

    • screw_count: The number of scre holes to generate. If a cable hole is added and a screw hole would interfere with it the screw hole is not created
    • screw_diameter: The diameter of the scres to be used in mm
    • screw_edge_inset: How far in off the edge of the plate should the center of the scre hole be.

  • Cable Hole Parameters

    • cable_hole: Generate a hole in the back of the case for a cable. true or false
    • hole_width: The width of the screw hole in mm
    • hole_height: The height of the screw hole in mm
    • cable_hole_down_offset: How far down from the bottom of the plate thickness should the screw hole be placed.
    • cable_diameter: The diameter of the cable. Used to create a strain relief clamp that holds the cablein place so it does not tug on an internal conector

  • Custom Cutout Shapes: These options allow for defining extra cutouts on the plate for things like oled displays or encoders.

    • custom_polygons: Define a set of custom polygons to be cutout of the top plate
      • type: The type of shape to create. Options: circle, rectangle, polygon
      • r (circle): Radius.
      • width (rectangle): Width of rectangle. If only width is defined the shape will be a square with matching height and width
      • height (rectangle): Height of rectangle. If only height is defined the shape will be a square with matching height and width
      • points (polygon): List of x, y coordinates that define the vertices of a polygon
      • path (polygon): List that defines the order that the points should be traversed to draw the shape. If this is omitted the list of points will be followed in the order the are defined
      • coordinates: The coordinates defining x and y distance from the origin the cutout should be moved from. 0, 0 is the bottom left of the keybaord. For circle and rectangle the origin is the bottom left of the shape. For polygon the origin is defined by the points in the points list
      • EXAMPLE:

        "custom_polygons": [
            {
                "type": "circle",
                "d": 7.5,
                "coordinates": [
                    [114.3, 110]
                ]
            },
            {
                "type": "polygon",
                "points": [
                    [0, 0],
                    [-10, 13],
                    [5, 17]
                ],
                "coordinates": [
                    [5, 5]
                ]
            },
            {
                "type": "rectangle",
                "width": 12.5,
                "coordinates": [
                    [0, 0]
                ]
            }
        ]
        

  • Custom PCB Parameters: These options are to be used when you want to have a case generated to fit a specific PCB inclusing the mounting holes in the PCB. This was setups spcifically to handle easily creating a case for a PCB built in kicad. Milage may vary for other PCBs

    • custom_pcb: Generate the case to fit a specific PCB. true or false
    • pcb_width: The width of the PCB
    • pcb_height: The height of the PCB
    • pcb_top_left_coordinates: The coordinates that should represent the top lef tcorner of the PCB. In kicad this would be the actual x,y coordinates of the top left corner in the PCB editor.
      • NOTE: If using a custom PCB and custom screw holes for the PCB the custom_screw_hole_coordinates_origin parameter must be in the same coordinate system as the value of pcb_top_left_coordinates
    • pcb_left_switch_center_x_coordinate: The X coordinate for the center of the left most switch on the layout.
    • pcb_top_switch_center_y_coordinate: The Y coordinate for the center of the top most switch on the layout.
    • pcb_case_top_margin: The space between the top edge of the PCB and the inside of the case wall
    • pcb_case_bottom_margin: The space between the bottom edge of the PCB and the inside of the case wall
    • pcb_case_right_margin: The space between the right edge of the PCB and the inside of the case wall
    • pcb_case_left_margin: The space between the left edge of the PCB and the inside of the case wall

Example Output

Output Format

• The program exports 4 different files for each model it is set to generate
  • top: the top part of a complete case. meant to be screwed to the bottom to make a complete case
  • bottom: the bottom of the case with screw posts to connect it to the top of the case
  • plate: the plate only eith no case walls. The palte still includes the mounting holes
  • all: This is just a render of the entire case as one peice. Not really meant for printing just for reference
• The files will be exported into a folder within the same folder where the layout json file is. The folder will have the name of the layout file without the .json extension
• There will be separate scad and stl folders in the export folder

Small Layout Test

• This shows testing done using a msall layout and changing the printer build plate settings to force it to split the design up.

  This is an image of the layout design on keyboard-layout-editor

  

• if just passing in the layput fle with the "-i" option the entire case will be generated. An example of the top of the case of that model is shown bellow

  

• using the "-a" option it will generate files for 2 different models that make up the entire layout. The images bellow show the separate section top case models

  

  

• using the "-e" file will generate an exploded view of the case where all the sections are shown but they are offset to be viewed more easily. See the iamge bellow

  

Full Size ANSI

• Bellow is and exploded view of the generated model for a full size keyboard

  

Printed Part

Here are some pictures of that raw parts from the printer and the assembled case

• Topside of Top

• Underside of Top

• Top edge on view

• Focus on stabilizer cutout

• Bottom

• Bottom edge on view

• Assembeled Front

• Assembeled Side

• Assembeled Tilt

Acknowledgements

Shout out to Will Stevens https://github.com/swill for his plate generator that provided inspiration and very useful measurements. The swillkb plate and case generator is here http://builder.swillkb.com/