SRM-20 / How to make a LED circuit board

Created Date: 2015-07-03/ updated date: 2018-03-13
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    Summary
    FabLab Kamakura has held CNC milling machine classes for beginners. This page is a summary of that class. In this tutorial you can learn how to make a simple circuit board with a LED.
    We explain how to make the circuit data using a software called Eagle, and how to mill the circuit board using the milling machine (SRM-20).

    Materials

      Tools

        Blueprints

          Making

          • Here we explain how to make the circuit data for the LED.
            • Decide where to place the battery box, LED, and resistor. 
              There is a command line at the top of the window. 
              Type in “move”, press Enter and click the components to move them.
              (Or you can click the [move command] on the toolbar at the left side of the window)
            • When you have finished arranging all of the components, wire them together. 

              Execute the Route command to connect each of the components’ pins. 
              Once you click one end of a component, the end of another component will be highlighted. Click and create a path to connect those ends.

            • First, connect the negative end of the LED to the negative end of the battery box.

              ※ Do not click and drag. Just click.
              ※ Be careful not to double-click or the wiring will stop at that point.
              ※ Make sure that the red lines DO NOT cross over.
            • Connect the rest of the components.

              ・Positive end of the LED → One end of the resistor
              ・Other end of the resistor → Positive end of the battery box.

              ※ If you want to change the angle or curve of the wiring,
              right-click during wiring, or use the toolbar at the top of the window.
            • If you want to erase the wiring, execute the Rip Up command and click the wire.

            • Execute the Polygon command by typing "Polygon" or clicking the [Polygon command].

              From the top of the window, change the layer form [1 Top] to [48 Document]

              ※ The outline of the board has to be saved on a different layer in order to save it separately from the other data,
            • Draw the outline by clicking several times.

              When the beginning and end of the line is connected, the inner area will turn into a transparent white color and the shape will be finalized.

              ※ If you press ESC before the shape is finalized, all of the lines will be erased.

            • Now, we will export the PNG file of the circuit's traces.

              Execute the Layer command and select [None] to deselect all of the layers.

              Select the numbers of [1 Top], [17 Pads] and [18 Vias] to show only the traces of the circuit, and press [OK].
            • From the menu at the top of the screen,  select [File] → [Export] → [Image] to export the circuit’s data.

              Browse and select the place to save the file, type the file’s name and save it as a png file.

              Check [Monochrome], change the resolution to [800 dpi] and press [OK] to save.
            • Select only the [48 Document] layer and repeat the steps from [Export to png(2)] to save the outline file.
          • Fab Modules is an online, open source, CAM software which we will use to convert the [.png] file to [.rml] file (path data). 

            Go to the site and follow the steps below.
            • Open an internet browser and go to the following link.
              fabmodules.org


              Click [input format] to show the extension names. 

              Select [image(.png)].

              Select the png file and click [Open].
            • Select the bit's size by clicking [process] and selecting [PCB traces (1/64)].


              ※For exporting the outline data, select [PCB outline (1/32)].
            • Click the [calculate button] located under process, to create the path data.

              Once the tool path data appears on the left area of the screen, click the [save button] to download the data.
            • Repeat steps (1) to (4) to create and save the outline’s path data.

              ※For exporting the outline data, select [PCB outline (1/32)] in step (3).
          • Here we explain how to mill the circuit board with the SRM-20.

            We will use a software called [VPanel] (provided by Roland) to export the [.rml] data.
            • Turn on the SRM-20.

              Turn on the computer that is connected to the SRM-20 and open [VPanel].
            • Here we use VPanel to set the bit’s origin.  There are two settings.
              • Machine Coordinate System
                   The preset of the bit’s origin.

              • User Coordinate System
                   The user determines the bit’s origin.

              This time we will use the User Coordinate System.
            • After inserting and securing a 1/64” bit in the spindle, click the [X/Y arrows] to set the origin of bit. Carefully click the [Z arrow] and lower the bit until it is slightly above the board. 
            • Now we adjust the bit so that it touches the board.

              While holding the bit with one hand, loosen the setscrew on the spindle with a hexagon wrench, carefully place the bit on the PCB, and gently tighten the setscrew. 

            • ※ DO NOT tighten the setscrew with too much force or you may damage it.
              ※ DO NOT drop the bit on the board or the tip may break.
            • Click [Add] and select the [.rml file] for the circuit's traces.

              When the [Output] button is pressed, the machine will begin to mill.

              ※If the previous files appear in the Output File List, delete them before opening the [.rml] file.
            • For the outline of the circuit board, change the bit to 1/32”. Use the [Z arrows] and hexagon wrench to adjust the bit. Then, click only the [Z button] under Set Origin Point to re-set the bit’s origin.

              ※DO NOT forget to re-set the bit’s origin ([Z button]), or the bit may break.
            • Repeat the previous steps from Send the Cutting Data for milling the outline of the board. ( [Cut] → [Add] → [Select the .rml file] → [Output] )
            • When the milling is done, open the front window, loosen the 4 screws and take out the orange stage.
            • Pour the solvent between the orange stage and the PCB. Insert the scraper between the stage and the PCB and carefully remove the board.
          • Begin to solder from the smallest components.

            [LED] → [Resistor] → [Battery case]
            ※Be careful! The LED has polarity. The side with the green line is - (anode).

            • Flow a little amount of solder into one of the pads
              Wet the soldering iron with a little solder. Press the tip of the soldering iron on a pad. Briefly press the solder on the board and flow it on the pad. Release the solder, then the soldering iron form the pad.
            • With a tweezer, hold the small component and press it on the soldered pad. Warm that pad until the component is connected to the board. Solder the other pad.
          • Insert the battery.

            If the LED turns on your circuit board is complete!
            • ・Press the tip of the soldering iron on the board and warm it up before flowing in solder.
              ・Turn off the soldering iron whenever it isn’t being used.

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