Introduction: Custom PCB Nightlight
A lot of visitors come through Other Machine Co. headquarters in San Francisco on a regular basis, and we like making them something nifty that illustrates what the Othermill can do to remember us by.
This neat little nightlight incorporates the Othermill's circuit board-cutting abilities, some crafty non-circuit cutting, and results in a custom-made item that is suitable for all of a small child's bedtime-monster-vanquishing needs.
In this tutorial, we also include a bit of the hows and whys of machining so you can take the knowledge and apply it to making other things like this on the Othermill.
Step 1: Tools and Materials
- Computer with Otherplan installed
- Flat end mill, 1/32"
- Soldering iron and solder
- Wire nippers
- Hot glue gun and glue
- Third set of hands (optional)
- Printed circuit board blanks, single-sided, FR-1 enough for three 2"x2" sheets
- LEDs (2) A soothing color, like red or amber, is probably best.
- Resistors (2) that work with your LEDs. Most LEDs need a resistor in line with the power to keep them from burning out immediately. If you don't already know what resistor you need for your particular LED, refer to this online LED resistor calculator.
- Battery, coin cell, 3V We used CR2032s for this project; you can find them at most hobby and electronics stores.
- Battery holder that fits your coin cell. Keep in mind that the board is made to accommodate the CR2032 holder, so if yours varies too much it might not fit the board. We used a standard through-hole CR2032 holder.
You will also need a reasonable working knowledge of soldering simple circuits. There are some excellent soldering tutorials available online.
Step 2: Cut the Board
The wonderful thing about this nightlight is that it's pretty much limited only by your imagination (and to a certain extent, the laws of physics). We've provided a handy, easy-to-cut file for a basic LED circuit board that you can use to light up your creation. It's up to you to create the decorative part of the nightlight.
We created this very simple circuit in EAGLE, a common circuit board design platform.
To cut the board:
- Download the file and load it up in Otherplan. (If you haven't used Otherplan before, you might want to try our Hello World tutorial first.)
- Load the correct tool (we used a 1/32'' end mill) and go through the tool touch-off process.
- Load the FR-1 blank, copper-side-up, onto the machining bed and secure firmly with the double-sided tape.
- Make sure your safety windows are in place.
- Click on "Cut Traces."
- Once the traces are cut, make sure everything looks good, and click on "Cut Outline" to cut the through-holes and the outline.
- Save the rest of the FR-1 for later.
Step 3: Choose a Design
One of the funnest parts of this project is, of course, finding a suitable image for the nightlight.
We found some lovely free clip art online that was relevant to the interests of the very nice 9-year-old girl for whom we were making this jolly light-up trinket. We downloaded the image, adjusted it slightly in a graphics program so it matched our artistic vision, and then determined how big it had to be to accommodate the tools we had available (more on this in a moment).
Then we had to decide if we wanted it to be a negative or a positive image. A negative image would have the light shining through the image itself, while a positive image would have the light shining through the negative space around the image. We decided to go for the positive image to start.
Step 4: Make the Image Into Toolpaths: an Overview
Now we need to use computer-aided machining software (CAM) to convert the art into toolpaths. Toolpaths are the series of coordinates that determine the movement of the tool during a machining operation.
Toolpaths are usually automatically generated for maximum efficiency and to make sure the actual physical tool can make the cuts you want. The CAM package takes the graphic, turns it into a toolpath that makes sense for the design, then translates that into code the milling machine can understand.
There are a ton of CAM software packages out in the world. Prices range from free and open source to "If you have to ask how much, it's probably really expensive." Our CAD and CAM guide gives suggestions and goes into detail. Try as many different kinds as you can so you can see what you like best. Lots of CAM software sites offer limited-time free trials, and they also usually have online tutorials and user forums that show you how to get the best out of the product.
The Othermill works with G-code, a standard machining language, which pretty much any CAM software can generate.
Step 5: Toolpaths: the Basic Workflow
Before you convert your images into toolpaths, there are some questions you may want to ask yourself about your project. These are general and don't necessarily apply to this project, but they're good to think about nonetheless:
- What sort of material are you cutting and with what tool?
- Is the image positive or negative? (Is the image a hole in the material or a raised area?)
- Are you cutting an inlay that will have to fit in another piece of material?
- Are there any areas in your design that are too small for your smallest tool to cut?
- Do you have the right feed and speed settings (more on that below) for the material you're cutting and the cut you want to make?
Every CAM package has a different user interface, ease of use, and learning curve. Although the terminology may differ from app to app, here's the basic process to follow:
- Import your image into the CAM software.
- Select the areas you'd like to cut, and choose how you'd like to cut them.
- Have the software calculate the toolpaths.
- Save the toolpaths as G-code (or export them, or however your CAM software handles things).
- Import the G-code into Otherplan.
- In the View menu of Otherplan, select "Show Motion Plan" and make sure it looks good on the virtual machine bed.
Having a project is a great way to get you exploring and learning the features of your CAM software. While the learning curve might be a little steep, with a few projects under your belt, you'll be a dab hand in no time.
Feeds and speeds is machining shorthand for the combination of the RPM of the Othermill spindle (the spindle speed), the rate of travel across the surface of the material (the feed rate), and the rate at which the spindle moves up and down (the plunge). Every material has a slightly different feed and speed depending on the tool you're using and the kind of cut you're making.
For this project, Otherplan will automatically calculate the feeds and speeds based on the .brd file for the circuit board. For the bezel of the nightlight, we used a spindle speed of 10,000RPM, a surface feed speed of 6mm/sec, and a plunge of 2mm/sec.
Step 6: Generating Toolpaths: Things to Look For
When choosing your design, keep in mind that if it's too detailed and fine for the end mill you're using, chances are either your CAM software won't render it or it won't cut correctly when you import it into Otherplan. Most CAM software has a simulation mode that'll warn you if it's unable to cut something properly.
If you want to get fancy when generating toolpaths, you can generate a few different files to make your work slightly quicker. For example, you can generate a rough pass that outlines the basic shape you're cutting with a larger end mill, then generate a fine pass that cuts the smaller details with a smaller tool. The pictures above show what this looks like in the program we used for our G-code.
For example, for the image in the previous step, clearing the large side areas with a smaller end mill would take a while, so we used a 1/8'' two-fluted flat end mill to do the rough outline and the clearing, and a 1/32'' two-fluted flat end mill to do the finer outline and details.
Once you've made all your toolpaths and produced your G-code, you're ready to cut!
Step 7: Cut Your Nightlight
Two steps back, you imported your G-code into Otherplan and turned the motion plan on to see how it rendered. If everything looks reasonable, you can cut your design.
- Secure your sheet of FR-1 to the Othermill bed with the double-sided tape. Tamp it down hard; your design will suffer if the material moves around, and it could also break your end mill.
- Measure the material and enter the material type and dimensions into the Setup Material panel.
- Use the Tool Change panel to set the tool you'll be using, and go through the tool location dialog boxes.
- Make sure everything looks correct on the machine bed and in the machine itself.
- Finally, click on Cut!
The Othermill will begin cutting your board. Depending on the files you created and how complicated your design is, your project might take a while to cut. Make sure you're settled in and ready to stay in one place for a bit because you should never leave a running mill unattended.
Step 8: Assemble Your Nightlight: the Board
Lay out your components (LEDs, resistors, battery holder, and battery) on the circuit board you milled earlier.
- The positive leads (the slightly longer ones) on the LEDs go into the outermost holes in the board.
- The resistors drop into the holes right next to the positive LED leads.
Bend the wires of all your through-hole components so the wires are holding the components more or less securely. Make sure to leave a little bit of play in the LED wires so you can move them around a bit.
Step 9: Solder Your Board
Since we're building everything on one side of our single-sided board and we're doing it with through-hole components, solder the wires on the same side of the board as the components. Be sure to clip the wires on the back of the board close with the nippers.
Feel free to play around with your component positioning. For example, you can have the LEDs on the non-copper side of the board, pointed up, and use various materials to make legs or some other kind of shield to keep the copper on the bottom from coming into contact with things. We positioned everything on one side of the board for quickness and ease of layout (and also to make the most of the components we had around the office).
Step 10: Glue Your Nightlight Together
Heat up your hot glue gun and bring all your pieces together.
- Lay your circuit board and design flat and flush with one another.
- If your design is not the same size as the circuit board, center it or position it wherever else you'd like it.
- Lay down a bead of hot glue at the joint of the two pieces.
- As the glue cools, bend the design up so that the circuit board is the base. Adjust the angle of your nightlight where you want it.
- Once the glue for that joint is dry, flip the nightlight so that the design is face down.
- Take a 2''x2'' piece of FR-1 and lay it down across the top of the cutout, copper side up.
- Once again, as the glue cools, stand the nightlight up on its base (the circuit board) and bend the FR-1 you just glued to the top down and over the battery holder, as shown in the photos. The copper will act as a reflector for the LEDs.
Step 11: Add the Battery
Take your handy CR2032 coin cell and pop it into the battery holder. The LEDs should light up, and all nightmares should be banished.
If you have any questions about this process, feel free to add a comment or contact us at firstname.lastname@example.org. And if you make one, be sure to show us — we'd love to see it!
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