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Step 3: Print Your Inside Frame and Ring

Picture of Print Your Inside Frame and Ring
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The hardest part of this step is probably going to be finding a high-resolution printer. I did mine on a resin printer. FDM printers won't be able to replicate the tiny arms on the inner frame that help center it in the mold.

All files are located at: https://www.thingiverse.com/thing:3550573 be sure to scale both files according to your ring size. The original files are for my right ring finger, which is size 10 and 3/4. If your ring size isn't 10 and 3/4, scale it using this chart before you print it: http://www.mazaldiamond.com/blog-en/wp-content/up...

Since the inside diameter above is shown as 0.806 inches for the original 10.75 size, (You're looking at the radius in the last picture above, so we're doubling it.) then if your ring size is 9 and 1/2, looking at the chart you'll see that's a diameter of 0.762 inches. 0.806 divided by 0.762 is 0.9454ish, so just scale the models to 94.5% of their current size before you print them. Note that bigger ring sizes mean more room for more resin around the RFID chip, so I wouldn't suggest making this a pinky ring. Middle finger or thumb is probably the safest bet if you have small hands. I could also be talked into making a larger profile ring STL if you need it, but that would probably be less comfortable to wear.

Random note that the absolute best way I've found to remove delicate resin prints from the supports is a Dremel, a cutting wheel, and going very slowly. Make sure when you're cutting you move the cutting wheel up and down so that it doesn't bind as you're cutting and you should be fine. It's better to cut the support and then grind/sand it down flat against the part than to try and save a minute or two and end up breaking the part. Focus on getting it out of the supports completely first and only then sanding things flat where the supports were.

Darr2474 months ago
22.12 meter wavelength (13.56MHz typical) = 870.8635 inches... so a 1/32 wave antenna should be about 27.25'' long. What really matters is the diameter of the antenna in the reader. Check this out https://www.limpkin.fr/public/NFC/RFID_antennas.pdf