2D vs 3D CAM: The Difference You Can Feel in Insoles and Molds
Read time: 6 min
When you hold a finished insole or mold in your hand, you feel very quickly if it is "right". The surface should feel smooth, the arch and curves should flow naturally, and there should not be small steps or sharp marks that distract the foot or the patient.
That final feel is not luck. It comes from how the CAM software tells the milling machine to move.
In our software we have a CAM module that can mill insoles and molds from materials like EVA, polypropylene and, for molds, often MDF. You can set up different milling tables, so every machine and every block type can have its own ideal settings. We support any open milling machine or router, so you can use the equipment you already have or choose the one that fits your workflow.
For a long time, almost everything was milled with what people usually call 2D CAM (or 2.5D CAM). That works very well and is still widely used. Recently we added full 3D CAM to our module. On the screen it looks like "just another option", but in the material you can clearly see and feel the difference.
This is the story of what actually happens when we project from the top in 2D CAM, and what changes when we follow the real surface in 3D CAM.
2D (2.5D) CAM – Projecting from Above
With 2D CAM in our system, we do not think in layers. Instead, we project from above.
You can imagine the insole or mold lying inside the block. The software looks at it from the top, like a shadow on the floor. It takes that top view and starts calculating where the cutter has to go. All the decisions about where to move are made from that flat top view.
So with 2D CAM we say:
"Here is the outline of the insole or mold seen from the top."
"Here is where we want to cut around it and over it."
The tool then moves over the block following that top-view projection and cuts down to the final height. Whether it goes to that depth in small step-downs or in a single depth is a technical detail. For you as a user, it is always one continuous job: the machine starts and cuts everything away in one go based on that projection from above.
This way of working is fast, clear and easy to calculate. For simple shapes it gives very good results. For many years this has been the standard way of milling insoles and MDF molds.
But once the shape becomes more three-dimensional – higher arches, deeper heel cups, smooth transitions, corrections, more complex mold shapes – this top-view way of thinking starts to show its limits. Because we are projecting from above, the distance between passes on sloped areas is not perfectly even on the actual surface. The cutter still does its job, but on curved zones you often see and feel more visible lines.
On MDF molds you might see this as clear milling lines in the curved areas. On insoles you feel small ridges where you would actually like a smooth, flowing surface.
This is where 3D CAM changes the story.
3D CAM – Following the Real Surface
With 3D CAM, we stop thinking in "shadows from above" and start thinking in real 3D surfaces.
Instead of projecting the insole or mold down onto the top plane, we take the actual 3D shape and follow that shape directly. The toolpaths are no longer calculated on a flat view; they are calculated on the surface itself.
Here is the key sentence that sums it up:
With 2D CAM we project from above and calculate offsets in that top view. With 3D CAM we follow the real 3D surface and make our offsets on that surface.
In practice, this means that the cutter is always trying to stay at a constant distance from the true insole or mold surface. It moves left–right, forward–back and up–down at the same time, smoothly flowing over the arch, through the heel, and into the forefoot, or across the curved surfaces of a mold. The spacing between paths is measured along the surface, not just in a flat plane.
On the finished product this is very easy to see. A 2D-milled insole or MDF mold often shows stronger lines, especially in curved areas. A 3D-milled part looks calmer and more even, as if the machine has already done most of the polishing for you. When you run your fingers over it, it simply feels more "finished".
Why the 3D Approach Feels Smoother
The smoother finish of 3D CAM comes from a few simple ideas.
Because we offset on the surface, the distance between passes stays much more constant on curved areas. On an insole arch or a heel cup, that means the little ridges between passes are lower and more regular. On an MDF mold, transitions and curves feel much closer to a sanded surface straight from the machine. Your fingers feel a continuous curve instead of many tiny lines.
Because the cutter follows the shape, more of the side of the tool is used instead of only the tip. In EVA this gives a cleaner cut with less tearing or fuzziness. In polypropylene it creates a smoother, more glossy look. In MDF it means fewer visible milling marks and less sanding work.
And because the paths are calculated directly on the 3D shape that you designed, the milled result stays very close to that original design. The arch height, heel cup, wedges and lifts in an insole are not approximated from a top view, but followed in 3D. The same goes for mold geometry: the curves you draw are the curves the machine actually follows.
For you, this means less grinding or sanding, less chance of changing the shape by accident during hand finishing, and more trust that the next pair or next mold you mill from the same design will feel the same.
How This Fits into Your Daily Work
In a real workshop or lab, you work with different machines, tools and materials: EVA, polypropylene, MDF and others. Our CAM module is built for that reality.
You can set up separate milling tables for different block sizes, materials and machines. Each table can have its own tools, speeds and strategies, including whether you want to use 2D projection or 3D surface following for a certain product. You decide what is best for your workflow, and the software remembers it, so the process stays simple for the user.
Because we support any open milling machine or router, you are not locked into one specific brand. You can keep using the machines you already own or add new ones later, and still generate toolpaths from the same CAM module.
The step from 2D to 3D CAM simply means that your milling machines can now treat your insole and mold shapes as true 3D objects instead of flat projections.
Conclusion
And that is what your patients and customers feel and see at the end: a smoother surface, more natural curves, and a product that reflects the shape you actually designed in the software—whether it is an insole under someone's foot or an MDF mold used in your production.
The difference between 2D and 3D CAM is not just visible on the screen. It is something you can feel with your fingers and something your patients will notice every day they wear their insoles.
Experience the difference yourself
Want to see how 3D CAM can improve your insole and mold production? Book a demo and discover the possibilities of our CAM module.
Co-Founder of LutraCAD, I'm a passionate software developer with a keen interest in 3D printing. Merging technology with creativity, I'm dedicated to pushing the boundaries of design and innovation.
Tags: CAM Software, 3D CAM, Insole Production, Milling Technology,