The Perfect Buckle

thingiverse

The buckle of my fanny pack broke after falling from a third floor window, giving me the perfect excuse to design something to 3D print! After checking out buckles on Thingiverse and reading comments, I decided to set some goals for the project: - It must print without supports, - The buckle has to look like the original, - It needs to be as strong as the original, - Opening and closing should work smoothly with no jamming, - It can be used with already stitched webbing, - And it has a double loop on one side for strap adjustment. After many iterations, I came up with a very solid and practical replacement. I've been using it for about two weeks, and it's just as good as the original part. I was looking for a name that had more charm than "replacement buckle" and showed my friend "The Perfect Buckle", which fit perfectly. This buckle is meant for a strap 36mm / 1.42inch wide. You should be able to scale it up or down to fit other widths, but I haven't tried it myself yet. Expect some more friction if you scale it down though, since the gap between the parts will also decrease. **How to Print** Print without supports. Use PETG filament for best results. ABS works well too, but it may warp a bit, making the insertion and release less smooth. I haven't tried PLA because I'm not sure it will be strong enough for this application (but if you try please share your results!). The buckles shown in the photos have been printed on a PRUSA I3 MK3 using 0.2mm layers, 3 perimeters, and 30% infill. Black and red parts are PETG, and blue and yellow parts are ABS. **What Files to Print** If you're in a hurry (but still managed to read up to this point, thank you), print the [thePerfectBuckle.stl](https://www.thingiverse.com/download:6800219) file, which includes everything you need in one convenient package. I did some experiments adding decorations to the female part of the buckle, which is tricky since it has to be printed vertically. I tried a few designs until I settled for the one in the photos, inspired by the DANGER EJECTION SEAT stickers found in aircraft. If you want the decorated version, use the [buckleFemale--decorated.stl](https://www.thingiverse.com/download:6800224) file. Much nicer decorations would be possible if the female part of the buckle printed horizontally, which would require some sort of support. In this configuration, the bridging capability of the printer can be exploited, meaning the supports are only needed at the side openings, so I decided to add some detachable supports there. To print this version, go for the [experimental--buckleFemale_decorated_with_supports.stl](https://www.thingiverse.com/download:6800225) file and print it without supports since they're already included in the file. After printing, detach the side supports and that's it. Printing this horizontal version using filaments of different colors makes for a very nice-looking buckle, but keep in mind that insertion and release may not be as smooth as in the vertically printed version (because the bridges will hang down a little, increasing friction). BTW, if you come up with a nicer decoration for the buckle, please share your make! I uploaded the Fusion360 files for you to play with them; the decoration is in Sketch14. **How to Assemble the Parts** If your webbing is already stitched in place like mine, pass the male pin through its strap and then set it in place in the male part of the buckle. Do the same for the female part. If your webbing is not yet stitched, set the male pin in place and then pass the webbing through the loops. The female part requires its strap to be stitched anyway, so you can add the pin and then sew the strap or the other way around. **UPDATE 22/09/2019:** I've now been using this thing for a couple of months, and it's been working well. A minor nag was that with enough pulling force and some twisting, you could actually open the buckle. To solve that, I tweaked a bit the hooked ends of the male part and thinned the female internal walls accordingly. It locks very tight now. Enjoy!