FIDIM 2.1 AFO Leg Brace

FIDIM - "Fine, I'll do it myself" Since I have had so many issues with manufactured braces breaking and/or being entirely too expensive.

This is an evolution of a brace design that I have been working on for some time. The older versions used a steel hinge that had to be fabricated, making them less accessible for people that need them. This one has a somewhat better fit (for me) uses slightly less material (~900 grams per brace) and uses a flexible TPU "flexihinge" instead of a fabricated steel one. You can easily find hook & loop (Velcro) straps online. I used adhesive Velcro pads to secure the straps to the braces. The straps rarely need to be replaced, but won't last forever.

I recently tweaked the design of the lowers to eliminate the need for the rear bumper, and named the files "FIDIM 2.1 LOWER". Those are the ones that I am currently using. I recommend getting adhesive backed foam rubber and sticking it on the back of the braces where the uppers and lowers meet. This will reduce shock and significantly reduce noise from the upper and lower snapping together when you take a step. The bumpers were intended to take the place of that foam rubber pad, but they didn't work particularly well in my opinion. Perhaps a softer TPU? Feel free to try it. That adhesive pad will need to be replaced roughly every month. It absolutely takes a beating.

I also updated the design of the Flexihinges so that they will last longer. The old versions lasted me about 6 months of constant use, but I have yet to break or stretch the new version after close to a year of using them. I named the file "FIDIM 2.1 Flexihinge" and included it here. Either hinge orientation will work. With the "U" cutout in the front, you will get more flex. With it in the back, you will get more "foot drop" support.

These can be adjusted with a heat gun, but I recommend that you download Blender and learn the basics of its sculpting mode. You can very easily change the shape of these before printing as if they were made of Play-Doh. When you are satisfied, try printing a hollow version with some cheap PLA and see if it fits.

I hope that I can help someone else that needs AFOs, but can't get them for whatever reason. I went without them for years (far too expensive) and they have vastly improved my quality of life now that I have them. Please do not commercialize this design beyond what it takes to cover the cost of materials. There are numerous braces already on the market, and I want this one to be free for all.

Print Settings:

I highly recommend Overture "Easy Nylon" filament for these. It is by far the easiest Nylon that I have ever used, and it is extremely tough stuff. It's also very reasonably priced. Overhangs aren't very pretty, but it is what it is. I have used these braces for about a year (as of 7/2/2023), and haven't had any issues with durability whatsoever. You'll need a temperature of about 250~260C. Use your discretion with bed temperature, but you may have to get aggressive with that. Nylon sometimes likes to warp and lift off of the bed. You can also try using a raft to mitigate that. I printed these with 5 walls and 100% infill, and used a 1mm nozzle with a 0.6mm layer height for speed. I am doubtful that PLA+ or PETG would be suitable for these since they undergo such cyclical stress. I am interested in hearing your results though if you try either. Standard PLA would likely be entirely too brittle. ABS may work, but you'll have lots of warping. Factory AFOs tend to be made from PP, but that can be very challenging to print with. The flexihinges and rear bumper were printed with a 0.4mm nozzle using a 0.16mm layer height. Use recommended heat settings for your brand of TPU. I have tried both Overture and Duramic TPU with a shore hardness of 95A. Despite both being 95A, the Overture is a little more soft and stretchy. It will permanently stretch after several months of use, and need to be replaced once it becomes a problem. The Duramic doesn't seem to stretch, but it will eventually break. Other brands may be better for this, but these are what I have tried as of typing this.