Support ring for harpless lampshade

thingiverse

If you have a pretty lamp, and a pretty lampshade, but the lamp is designed with harp-style shades, and the shade isn't harp-compatible, you need an adaptor. (In this case, an IKEA lampshade. Your mileage may vary.) The internet suggested I'd easily find a ginormous washer (1 3/8" inner diameter, 3" outer diameter) at my local hardware store, but that was optimistic. I initially made this as just a basic washer, but then I got carried away. This support ring fits snuggly around a type-A lamp socket, with channels for the wires on my three-wire shade, and towers to hold the shade's ring securely, and a subtracted-out cone segment to get it better bonded to the socket's flange. I haven't exposed it to the heat of a lamp for hours & hours, so I may need to reprint with more fill if it sags, but Makerbot's draft setting with no raft works great otherwise. (The .3MF file here is from Microsoft's 3D Builder app. If you need to resize the ID or OD, or have different channels, or a different depth cone, you can start with these bits, resize what you need, then subtract the inner cylinder and channels guides from the main disc, then place the cone inside the hole and subtract it as well.)