CAD/CAM for Orthotics
PodoCanada offers various types of custom insoles.Pedorthist Sal Sabbagh has been a DeskProto user for many years. Located in Ottawa, his company PodoCanada provides orthotic services both for consumers and for professionals:
- Custom orthotics to patients
- Central fabrication of orthotics to podiatrists
- Setting up digital labs in orthotic facilities
Insoles can be be made of hard plastic or of flexible foam.
Various types of orthotic insoles are possible: rigid orthotics in polypropylene or carbon fiber, and softer orthotics in EVA foam. Each type comes with different requirements for the design, and each type needs a different fabrication process. Common ground is that in all cases the process starts with measuring the foot.
Three methods to measure a foot, from traditional to state-of-the art.
Since 1998 PodoCanada has used CAD/CAM technology, in which the design is based on a 3D digital model of the client's foot. This digital model is captured using a 3D scanner. Several methods are possible: the scanner can scan an imprint of the foot in a foambox (a box with soft foam), an imprint in a vacuum pillow, or even make a direct scan of the foot.
An iPad with the 3D scanner add-on attached, and screenshots of raw 3D CAD scandata.
The scanning device can be an iPad with a scanning extension, however the most recent development is to use an iPhone. This is possible as the face recognition feature of this device is in fact a 3D scanner. A big advantage of using an iPhone is that no special hardware is needed, so the client does not need to travel to the pedorthist. Detailed instructions by PodoCanada explain this process step-by-step and make it possible to make this scan at home.
Screenshot of the Footmill software: both the 3D scan and the insole are visible.
To design insoles it is needed to use specialized CAD/CAM software: PodoCanada uses the program FootMill, made by CAD - CAM - Hinrichs in Germany. Footmill is a design software for insoles and shoe lasts.
At this stage of the process the pedorthist's knowhow comes in, making the insole a good or a bad product. Simply explained: the insole may not be a copy of the bottom of the foot, instead it needs to provide correction(s) in order to remedy the client's problem.
Footmill imports the 3D scan data (an OBJ file), the pedorthist designs the insole, and the resulting 3D design then is exported as STL file.
CNC toolpaths are calculated using DeskProto.
The resulting STL file is loaded in DeskProto, the toolpaths are calculated and the G-code file is saved. This process is fully automated, as the milling parameters for each type of insole are standard.
Sal Sabbagh says: "We tried many CAM softwares and they are all good. But our favorite is DeskProto (expert edition), the offset strategy."
Both small machines and large machines can be used.
As DeskProto supports many different CNC milling machines, PodoCanada can do so as well, for instance Shapeoko, Isel and Heiz. Professional clients of PodoCanada's services who want to fabricate their own insoles are supplied with a Shapeoko machine, as that offers good performance at a low price.
The fabrication process for hard plastic insoles: thermoforming over a PS foam plug.
The fabrication process of hard plastic insoles starts with CNC machining a positive plug (mold) in cheap PS (PolyStyrene) insulation foam. The insole is created by thermoforming: a flat sheet of plastic is heated and then vacuumed over this plug. PodoCanada has sufficient control over this process to prevent the PS plug to also melt and/or stick to the insole.
Demo-blocks for various models of insoles: casual, positive, finn, birk and dress.
The insoles in soft foam are fabricated by CNC machining from a block of EVA (a "rubber-like" type of plastic foam). The insole will be designed to match the footwear in use: Birkenstock (BIRK in the photo above), Finn Comfort (FINN), Dress Shoe (DRESS), walking shoe (CASUAL), or any other shoe type. In the photo the demo-block marked POSITIVE is the exception: this is a thermoforming plug.
A collection of various types of insoles, all made by PodoCanada.
As described above, PodoCanada offers a wide variety, both of products and of services. So the company needs tools that are sufficiently flexible to support all these processes.
Sal Sabbagh concludes: "DeskProto is very versatile and saves us time".