Milling

Prep Material

Use double-sided scotch tape to secure the FR-1 board to the spoilboard. I use the wide version, which covers more surface area. I use three long strips, evenly placed across the length of the board on the far top, bottom and middle section of the board. Do not overlap the strips or use too much as it will become difficult to remove. You'll want to wipe down the FR-1 board and the spoilboard with isopropyl alcohol with a paper towel. This will get rid of any debris, grease or finger prints from the surface.

Secure PCB to Spoil Board

When you're ready to install the material onto the spoilboard, carefully position the FR-1 board over the lower left corner of the spoil board. Square off the edges of the corner so they're both as flush as humanly possible. Then, press down on the material. I like to use a piece of paper towel over the material (prevents finger prints) and apply an even amount of pressure so all of the tape adheres to the spoil board.

Configure Material Profile

Bantam Tools software features a material profile preset for singled sided FR-1 boards. Select the Single-Sided FR-1 option from the material drop down. The size is already configured for the PCB blanks purchased from Bantam Tools. Under the placement dropdown, you'll need to input a value for the Z axis. This should be the thickness of the tape. We're using double-sided permanent scotch tape, which is 0.08mm. Type or paste that value into the input field.

PCB Placement in Bantam Tools

We can positioning our designs in Bantam Tools software by clicking on the placement button in the right hand sidebar. The dropdown menu has X, Y and Z input fields. I suggest adjusting the X and Y axis to 2mm to accommodate for a slightly offset PCB. This ensures we'll get nice edges. You also have the option to rotate the PCB. In my plan, I added a second PCB, positioned them close to each other and rotated by 180 degress. This allows 2x PCBs to fit on one FR-1 blank. 

Configure Milling Tools

We can assign milling tools to each PCB. I designed the PCB to work with a single 1/32in Flat End Mill. By using a single tool, we reduce the machining time since we only need one tool to do all of our operations. If planned accordingly, our traces and spaces have enough clearances for a 1/32in flat end mill. We also have the option to enable/disable milling the traces, holes and the outline. For this project, we can have them all enabled. Keep the "parts to mill" set to the "top".

Start Cutting

With everything setup and ready to mill, click the Mill All Visible button. The toolhead will start up and cut around the traces, drill holes and finally cut the board outline. Be sure to watch as the operation takes place. You'll want to be aware and cautious in case something comes loose.

This guide was first published on Jun 27, 2018. It was last updated on Oct 17, 2018. This page (Milling) was last updated on Jun 26, 2018.