Bantam Badge Tutorial
This script is based on the tutorial on Bantam Tool's website (https://support.bantamtools.com/hc/en-us/articles/360037787874-Light-Up-PCB-Badge), modified for our specific setup.
The Bantam Desktop Milling Machine (Bantam Mill, Mill) is a light-weight milling machine. For our shop this should only be used for milling PCBs for circuit boards unless you have explicit approval for your project from the Lab Manager. This tutorial will go over the initial setup using one of Bantam’s projects: the Bantam Tools PCB Badge.
When you open the Bantam Tools program, you should have a blank board on display. If the Mill is turned off, then you will notice that there is no fixture shown. Turn on the machine and you should notice the bracket appears in the graphics and in the configure menu (see orange arrows). If one does not appear, contact a Lab Supervisor to place the bracket as the tools are delicate.
To change the units in the program (this tutorial uses inches) click on the "View" tab at the top of the program window, then click on "Show units in inches" about halfway down.
The Bantam Tools program is well designed in that you can essentially work from top to bottom and get what you need done. The first step will be to make sure the vacuum hose assembly is out of the way of the bed, ideally attached to the spindle assembly, or hanging out of the back of the mill.
Once you verify that it is out of the way, click on the “Start homing” button (blue arrow in previous picture). Next, click on the “Change” button next to the tool row in the configure menu (the first button). This will bring up a dialog box at the bottom of the screen that will allow you to choose the tool you want.
Click on the “[unknown]” drop down menu then choose “1/32in Flat End Mill”.
Slide the tool all the way into the collet and tighten the collet with the wrenches on top of the PCB mill.
The next screen will have you verify the position of the tool. You want to make sure the tool is over the spoil board and not over the PCB material if it is already installed. (see red outline in previous picture).
You might have to click on “Locate Tool…” twice before it begins. The tool will then slowly make contact with the spoil board to verify its position.
Continue down the configure menu. You should have the 1/32in Flat End Mill in the tool menu, and there should be a bracket next to the Fixturing block. Now, select the material. It should be the Single-Sided FR-1. This is the standard PCB material that we will be using for most projects.
Next, click the down arrow next to size and you should see the dimensions (set to standard) for the PCB material. You should use the calipers to verify the dimensions, especially the thickness (Z) value.
Click the down arrow to show the placement window. Align to bracket should have “left” selected. X and Y should be 0.000in indicating the PCB is placed in the front left corner of the spoil board against the fixture bracket.
Most projects will use the white Nitto tape to secure the PCB to the spoil board. The Z value under placement is the thickness of this tape.
Measure the tape thickness without the backing. The tape is typically 0.008" but sometimes is slightly different.
Next, we will prepare the PCB blank and load it up. It is recommended that tape be applied to as much of the board as possible to prevent deflection in the PCB (especially needed for engraving). Make sure the edges are covered (next picture) then fill in the rest of the PCB (second picture) evenly spacing the tape and not allowing the tape to overlap. Overlapping the tape can cause the Z-thickness to be off and could potentially break a tool. Then, using the handle of the scissors or some other object, burnish the tape to make sure it is securely attached to the PCB.
On the configure menu, next to the move tab, press the Loading button to bring the spoilboard into position. Remove the protective backing from the tape and place the PCB on the spoilboard keeping in mind your origin (in this case, the front left corner). Press down firmly along the PCB to make sure the tape is secured to the spoilboard. Then place the probe clip onto the board.
We will now use the mill to make sure it knows where the top of the board is. In the top menu bar of the program, click on BitBreaker, then click on Probe Material Thickness.
The spindle will then move over the board to roughly the center. You can use the arrows in the pop-up to move the spindle if the tool is not over the PCB. Continue through the dialogue to check the thickness. You may have to click on buttons twice. Do NOT use the Z movement button to speed up the process. The spindle will very quickly accelerate and can easily break the bit if not stopped in time.
Once the thickness is done, REMOVE THE PROBE CLIP! If this is not done, the spindle and tool will crash into the probe clip, breaking the machine and/or the tool.
The vacuum assembly can now be placed back onto the spindle carriage. Make sure the vacuum assembly is fully seated, you should feel a click as you press it all the way in.
You are now ready to load your file. Click the Open Files button under plans. Navigate to C:\physics and select Bantam_Tools_PCB_Badge. Place the file 0.1" on both X and Y. This is to ensure the endmill will not crash into the fixture.
Make sure 1/32" Flat End Mill is chosen in the milling tools. By default traces, holes, and outlines are all selected to be milled. If you do not wish to keep the badge, turn off the outline as this will cut the time in half. We are now almost ready to mill.
Turn on the vacuum located in the drawer to the right of the computer. Do NOT touch the light green auto/man switch. Leave the vacuum on manual mode. The dark green switch will turn on the vacuum.
Double check the probe clip is not on the PCB board.
Verify both spindle belts are in place.
At the bottom of the configure menu, click on Start Milling.
During milling, be sure the spindle is turning and the belts remain in place. Should a belt break, hit the pause button in the bantam program. If a tool breaks or some other catastrophic issue, hit the emergency stop button on the bottom right side of the mill.
When the machine is done, the spindle we raise automatically and turn off. You can now turn off the vacuum.
Remove the vacuum assembly and put it out the back as before. Remove the end mill: use the wrenches on the top of the PCB mill to loosen the collet. The collet nut will then freely turn some and stop again. The tool will still be stuck in the collet. Putting slight pressure on the side of the endmill (careful, the endmill is sharp) to prevent it from falling, use the smaller wrench on the spindle and you can loosen the nut by hand to free the endmill.
Remove the side window and slide the putty knife under the PCB mill and gently pry the PCB off the spoil board.
The tape should peel off fairly easily. Please replace the windows and leave the PCB mill as you found it.
If you did not cut out the outline, this should be your finished product:
