How to Design and Fabricate a Table Top game using a CNC Mill and Laser!

Introduction

We love making projects with our CNC machines because they can work with a wide range of materials, and a wide range of manufacturing processes. In this project overview, we look at how a fun table top game was machined using plywood through both milling and laser engraving operations on the Carvera Desktop CNC!

Project Overview

We'll be looking at a few key components of the project in this post through the following topics:

1. Creating the Model in CAD
2. Preparing a 2-sided CNC Project
3. Milling Tool Paths
4. Laser Engraving Tool Paths
5. Assembly

All design files and a detailed video tutorial for this project can be found here on our wiki site.

Creating the Model in CAD

As you design your models for CNC milling, there are a few important things to keep in mind. The first is which CAM program you will be working with to prepare your designs for manufacturing. We'll be using Makera CAM for this project, which allows you to import a wide range of file types, opening greater flexibility for your CAD designs. But some CAM programs might require a particular type of file, which you need to plan for in the CAD stages.

We've chosen to design this model in Onshape, and kept the design as a series of 2D sketches as that suited the intricies of the design well for our purposes. We were able to layer the sketches of the top and bottom profiles, as well as keep things like the engraving profiles on seperate layers to make the CAM process a bit easier to do. Whever you create a 2D design, the 3D aspect of your project comes from the stock thickness set in CAM later on.

Preparing a 2-sided CNC Project

In order to make the board parts of this game project, we need to machine both sides of the stock. There's not one approach to creating a successful 2-sided project, but there are a few important steps to consider:

Creating a Second WCS

In Makera CAM, we can create a second Work Coordinate System (WCS) for the other side of our project. When doing this, we want to select the new origin position (bottom left corner by default) when the stock has been flipped:

Importing a 2-Sided Design

After importing our designs for the top and bottom sides of the part, we want to ensure they are aligned properly when the stock is flipped. Makera CAM offers a Quick Align tool that will automatically center your design on the stock center, and a Center to Center tool that will automatically center two designs to one another, making these crucial steps easier to do.

Using Alignment Pins

Using alignment pins can be a highly effective way to ensure your stock is aligned during a flip. Makera CAM's Create tools will allow you to easily create holes for your alignment pins, and the Mirror tool allows you to mirror your holes across the stock center to ensure they are perfectly centered for an accurate flip.

As you set up your CNC, consider using a thicker and more dense piece of wasteboard below your stock so that an effective hole can be drilled for your alignment pins. You also might use the corner clamp for the first side, but typically align only using the pins for the second side.

Milling Tool Paths

To manufacture this project, a number of Tool Paths must be created. Tool Paths are what tell the CNC how to manufacture the part using drilling, cutting, or chamfering operations. We walk through each Tool Path in great detail in our Tutorial Video for this project, but we'll also briefly overview them here. It's also important to remember that you need to make 2 board parts in order to assemble the project successfully.

Board Part - Side 1 (Bottom)

To manufacture the bottom of the board, we need the following Tool Paths:

1. 2D Drilling to create the holes for the alignment pins
2. 2D Pocket to create pockets for the magnets which hold the board shut when folded together
3. 2D Pocket to create pockets for the hinges to fasten the boards together
4. 2D Pocket to create the larger storage pocket in the center of the part
5. 2D Chamfer to create a chamfered edge along the perimeter of the design - note that we won't be cutting all the way through until the other side after the flip, but this will create a chamfered edge on the bottom side when the part is removed

Board Part - Side 2 (Top)

To manufacture the top of the board, we need the following Tool Paths:

1. 2D Pocket to create the holes for the cups
2. 2D Pocket to create pockets for the launcher bases
3. 2D Contour to create cut through the part along the outer perimeter - remember to create Tabs to hold the part in place when machining
4. 2D Chamfer to create a chamfered edge along the top of the part perimeter

And we'll discuss the laser engraving Tool Path in the next section.

Launcher Parts

In a seperate project, we can prepare the milling Tool Paths for the launchers to complete this game:

1. 2D Drilling to create the holes for dowel pins
2. 2D Pocket to create pockets for the ball and rubber bands
3. 2D Contour to create cut through the parts along the outer perimeter - remember to create Tabs to hold the parts in place when machining

Something else to consider for a larger project like this is your bit shank diameters. By default, the Carvera and Carvera Air are equipped with a 1/8" (3.175 mm) spindle collet, which works well for most applications. But to clear out the larger storage pocket in this project, a smaller 1/8" bit will take a very long time.

As such, you can take advantage of interchangeable spindle collets and bit shank adapters to utilize larger bits and smaller bits in a single project for optimal machining workflow.

Laser Engraving Tool Paths

The Carvera has a built-in laser engraving module, and the Carvera Air has a similar optional laser engraving module. This allows you to perform laser engraving operations alongside your milling operations with your Desktop CNC! Makera CAM also allows you to easily prepare laser engraving Tool Paths, as well as milling Tool Paths.

You can find recommended Speed and Feed settings for the Laser Engraving Modules on our wiki site, and its important to remember that not every material can be laser engraved safely. Additionally, you also must always wear proper eye protection and ensure you're working in a well ventilated space whenever using a laser engraver.

For this project, we've created a laser engraved profile on the top of the board part for a purely aesthetic feature, but one that adds to the overall appeal of this project nicely! You could also choose to create a similar design using a milling function, or bring in a logo or other design to engrave instead as you create your own custom projects like this one.

Assembly

After manufacturing the parts of this project using the strategies and Tool Paths we've outlined above, its time for assembly! First, you will need to cut the parts out of the stock by removing the tabs using a small handsaw and some sand paper to get a clean and smooth finish. You might find that some of the edges need to be sanded too, when making your parts out of plywood as we chose to.

For the Launchers, you will need to drill a hole that passes through the uprights for the launchers and the levers of the launchers in order to assemble them using wooden dowels. Smaller ~20 mm dowels can be glued into the front of the uprights via the pilot hole our CNC's machined, while longer ~40 mm dowels can be inserted and removed to assemble the launchers for use, or disassemble them for storage.

For the Board parts, we can glue magnets into the pockets created on the board bottoms, and we can attach the two board halves together using small 1" jewellery box hinges. With the board halves opened, you can easily store the launcher parts in the large pocket when not using the game, and the halves will close and latch together using the hinges and magnets!

Conclusion

After assembly, all that's left to do is to assemble the launchers, insert your cups, and play the game! The pockets for the launchers have been intentionally machined to be a bit bigger for easy rotation and aiming, and the cup pockets should be a snug fit to hold everything in place, even on the windiest of days!

Thanks for reading, and don't forget to check out the full tutorial for more info and a deeper dive on how this project can be made using the Makera Desktop CNC and Makera CAM!