Sunglasses Arm

thingiverse

When one of the arms for my sunglasses broke, I designed new ones for it. Understand that while this model really isn't intended for human consumption, there's no reason not to share it. I've included an image of the style of hinge this is designed for. It is not parametric. You'll notice in the photo, one arm is grey, while the other is green. The grey is ColorFabb PHA, while the green is some cheap generic PLA. The green was printed recently, after the left grey arm broke after a few months of use. Originally, I printed these vertically, so support material couldn't mess with any of the inner surfaces or tolerances I designed to, but that creates a weak section where a small cross sectional area meets a larger cross section, right on a layer transition. This is why the left arm broke on the first pair. The green arm is printed lengthways on the plate, with Meshmixer's supports (I did not include the baked support version because you can probably do better, this was intended as a test). This should mean the stress isn't applied directly to a seam between layers. I've included one fully designed right arm, the art-deco look of it is actually intended to reinforce the design a bit, on some very thin sections of plastic, and I've also included just the sleeve section that goes over the hinge, as a base for your own designs. Print Settings Printer Brand: Up! Printer: Up Mini Rafts: No Supports: Yes Resolution: To taste Infill: Kind of irrelevant as the walls are so close. Notes: When printing vertically, support material is not required. You'll get a good finish, but it will be quite weak. I recommend Meshmixer's supports if you print horizontally, as this will minimise the amount of cleanup required, to smooth the surfaces. The resolution is really irrelevant to this. The green arm, I printed at 0.3mm resolution, because I was impatient, while the grey at 0.2. The tolerances are fine either way, so the resolution won't impact the function. You may just want to tidy a rougher model up a bit more. It's down to how much finishing you want to do. Post-Printing Depending on the orientation you print this in, you may need to file or sand off the tags the support material leaves behind, for comfort. If you print this vertically, be careful not to flex the arms too much, or they will pop apart right where the hinge ends. How I Designed This After taking measurements of the hinge, I designed the shape in 123D Design. I'm absolutely NOT good at 3D modelling, so things like the curve downward and inward were quite difficult for me to work out, at first.