Improved Mayfair / Bemis Slow Close Toilet Seat Lid Hinge

thingiverse

I purchased a new "Made in the USA" slow-close toilet seat with built-in toddler seat from Amazon by Mayfair / Bemis in June 2018, and by October the lid hinge was broken from perfectly normal use. I decided to design and print (in PETG) a stronger hinge rather than spend my time on the telephone with a company that would probably just send me the same flawed part, ready to fail again. It took a few weeks and about 10 iterations to get it looking half decent, so it's not too offensive to the eyes. My first chunky square version worked great (once I printed it solid) but looked like I couldn't give a crap. The final version is not a perfect copy of the original - both because the original design has a flaw and I'm still learning to code OpenSCAD, so some aspects of the shape were hard to reproduce. But if you print both the left and the right hinge (only the left one breaks), it doesn't look bad - nobody noticed until I pointed it out to them, even though the plastics have slightly different white tones and I used 0.3mm layers. There are a couple things about the parts that I would still like to improve, but it has become a very low priority, so I thought I would share this version for now since I don't know how long it will be before I can work on this again. The main flaw I discovered during my measurements of the broken original left side, intact right side and first round of printing and testing is a gap between the hinge and the lid at the back / bottom of the hinge that is sort of visible when it's closed. The issue occurs when the lid is lifted because the 'no slam' slow close feature engages, so there is a bunch of force applied to the hinge part during opening, causing the hinge to flex and weaken where it starts to touch the lid. Thankfully the change meant it was easier to print since more of the bottom part of the print would be touching the print bed rather than needing supports and doesn't give it a bad appearance since the hinge now mates flush with the seat lid at the back.