Top Tips for Prototyping with your CNC Mill

At Makera, we strive to create desktop and mini CNC Milling machines and CAM software that are versatile enough to work with almost any material, and intuitive enough for any user to achieve success. But making mistakes is a natural part of the learning process, regardless of your skill level. In this article, we'll share top tips and best practices for prototyping your projects, helping you achieve greater success while also preventing costly mistakes along the way.

1. What is Prototyping?

In this context, prototyping is being used to describe an iterative approach to design and manufacturing. For example, I might want to create a product that is machined out of solid aluminum on several sides, with finished edges and tight manufacturing tolerances.

But before I jump headfirst into creating this part out of expensive materials and a lot of machine time, I might first create some test parts along the way. These parts might be made from different materials, they might be different sizes, they might not even be the same design or serve the same function as my final part. But they will allow me to test my design, identify possible problem areas, and most likely save time and money in the long run, too.

So, who should use this prototyping method? Everyone! Sure, some projects might be small and quick, with fewer complexities that might have room for error. But approaching every project through a design thinking approach with an iterative model at hand is one that will foster greater success and skill, every time.

2. Iterative Designs

The first step in prototyping your project begins at the design stage. For example, you might choose to test a single part of your design before manufacturing the entire product. This is especially helpful when testing tolerances, fits, and finishes.

Let's say I'm making a bracket that interfaces with a specific bolt, thread, or socket. Instead of machining the whole bracket for XXX amount of minutes, I could machine a test hole in a piece of scrap material in just X minutes to see if I have my fit and tolerances adjusted properly. I might repeat this process several times until I'm happy, then move on to making the whole part.

This can be done in your CAD or CAM software solutions. For example, you could export just a part of your design in CAD in order to test these components quickly. Or when using an all-in-one CAM solution like Makera CAM, you can select individual parts of your design to generate tool paths for, or even create basic 2D and 3D shapes to test with.

Another example of when you might want to utilize this approach is when machining a multi-sided part, or when using custom jigs or fixtures. The last thing you want is to realize you have an alignment error in your design after you've already spent the time machining one side of your part. In this case, make a very quick and simple design using the same number of sides or fixtures as your end product to test your positioning or flipping accordingly.

3. Gradual Machining Parameters

Something else to adjust in the CAM stages of your project would be your cutting parameters, such as your Speed and Feed settings. One of the most common mistakes we find both our users and ourselves making is choosing cutting speeds that might be a bit too fast or aggressive for our project, resulting in broken bits.

Breaking bits is certainly part of the learning process, but one that can be reduced by using a gradual approach to choosing your cutting parameters. For example, our recommended Speed and Feed settings are not the fastest or perhaps even the most efficient parameters the Carvera and Carvera Air can handle in many cases. But instead, a good starting point to test your tool paths for all scenarios.

We always recommend starting well below the maximums with slower operations to test your design and settings for any possible errors that might cause a broken bit or other damage. Again, you might choose to test these settings on just a part of your design or a smaller test piece rather than the finished product to cut down on machine time and material costs, too.

4. Material Selection

Another great tip for prototyping your designs is to use a selection of materials to cut your parts from. Let's again assume that I want my finished product to be manufactured out of a metal like aluminum.

Aluminum isn't a very cheap material to work with; it's also a material that we need to cut more slowly, and one that will quickly break our bits if we get our Speed and Feed settings wrong. So, in other words, the margin for error with metals is quite high.

So before I make my part out of aluminum, I might first make it out of a softer and cheaper material like foam, wax, or wood. These materials can be cut more quickly, so I can test my design efficiently before moving on to the harder material for the end result. And as these materials are much softer than metal, the likelihood of breaking a bit is far lower.

One of our favorite materials to prototype with is Expoxy Tooling Board. This material is relatively inexpensive, very soft, and also holds great detail and tight tolerances. As such, it's often a material you can use to test your parts on for both 3-axis and 4-axis machining operations quite effectively.

5. Simulations

And the last tip and technique you can utilize for prototyping your design is through tool path simulations. This is a virtual way of testing your designs, and one that you should utilize as you prepare your designs for manufacturing in your CAM software.

Virtual tool path simulations will show you how your part will be cut in a realistic visualization that should be pretty accurate, as long as you set your stock and origin positions correctly when setting up your CAM document. This is a quick and cost-effective way of preventing any major mistakes in your design before you begin to machine your parts.

The only thing simulations might not test effectively is your speed and feed settings. You should be able to identify where a bit might make a mistake or cut an area that is not intended, but you won't be able to necessarily tell that it's cutting too quickly. For this, refer to some of the tips and techniques we discussed earlier.

Conclusion

So, who should utilize these prototyping techniques when preparing their CNC projects? Again, everyone! As you begin a new project, consider breaking it into smaller components that can be tested in stages to ensure greater success down the road.

We all make mistakes, and sometimes things just go wrong. Better to allow these things to happen when the stakes are lower rather than when you are pushing a close deadline or when working with costly materials and cutting bits.

To learn more about these concepts, check out our Getting Started video series.