Making a hybrid encoder disk via JLCPCB pro.EASYEDA.com

[JamesNewton]

JLC PCB reached out to offer me a set of PCBs. Little did they know what they were getting into, because I don't need (yet) a PCB for the electronics (they are just too simple), but I do want to try getting the encoder disk itself made as a PCB. There is a strong case for the use of PCB material as an encoder disk:

• It's strong, but not brittle. Far stronger than the black cardstock I started with.
• PCBs don't warp or bend like fibers alone or metal alone. As ever, the combination is better.
• They aren't expensive (in quantity) and come ready made.
• The copper on either side makes it completely opaque (which plastics do not actually accomplish, which is why I used laser cut black card stock in the original)
• Most importantly: You can put a silkscreen on the surface for the STCG disk, as well as cutting the slots for the optical disk.

Because I now run Linux (Mint at the moment) I do not have access to CircuitMaker / Altium, or even Protel 99se anymore. I can use KiCAD, but frankly it's a poorly document, fragmented, powerful, but difficult to learn and quite complex program; using it would discourage others from experimenting. Instead, I chose to use the mfgrs EasyEDA program which can run in the browser. Specifically, the pro version:
https://pro.easyeda.com/

Steps

Setup EasyEDA

• Sign up for a free account.
• Start a new project
• In the project, add a new PCB (not a board)
• In the PCB editor, use the (H)elp system to do the tutorial to learn how to use it.

Copy Main Disk to PCB Outline

• Back in https://openjscad.com/ copy in the encoderdisk.jscad source and Shift-Enter to run it.
• Set the parameters as you desire, then select output: Disk Slots and press Update
• At the bottom, select DXF output, and press Generate DXF and then download the "output.dxf" file
• In pro.EasyEDA, zoom way in on the center at 0,0 until you can easily position the cursor near the home position, then select File -> Import -> DXF, change the layer to Board Outline, and click Import. Carefully position the cursor so it snaps to the center and click.
• Zoom out so you can see the entire disk. It should appear in a purple (or whatever color you select for the board outline layer)

Copy STGC Disk to PCB Silkscreen

• In openjscad.com, change the output to STGC Disk and Update. Note: You probably want to change the "slot break" setting to 0 first, so that there are no "stencil" lines in the segments.
• Change DXF to SVG and generate, then download the "output.svg" file.
• I had to edit the SVG file in svgEdit.Netify.app to first select everything, change the fill to solid white, then use the source edit (U) to find and remove the long outline path at the end of the file then "Apply Change" (or select the object and "ungroup" with the weird icon at far right, then select only the outline, and delete it) and then Export the result. This needs to be done to make sure the inside of each path gets filled in, and that the outer ring isn't covering everything else.
• In pro.EasyEDA.com, select the top (or bottom) solder mask layer
• Click (P)lace -> Image, select the output.svg file. Check that the image size is correct. You may wish to open the downloaded file and check the size mentioned in it's source. Click to Accept the image and place it. You can adjust the position and size after the fact (unlike the board outline slots) so don't worry.

The color on the display doesn't reflect the actual color which will be used in the production of the PCB; be sure to specify that when ordering the board.

Now, you can add a better circle on the outside of the Board Outline layer and delete the original multi-segment straight line version and do the same for the center hub. I'm trying to setup a (huge) via as the center hub so that it will be plated through and very strong, but I'm not sure they can mill / plate something that big.