50kg/110lbs load/force cell from cheap luggage scale

thingiverse

### Updates **2020-10-26:** Added two simple pressure pieces as FreeCAD and STL files. Print with 100% infill and preferably in PETG, ASA or similar (PLA works as well). ### What's this for? It's a low-cost device for measuring weights/pushing forces up to 50kg or 110lbs. Commercial force sensors that can do that are either really expensive or really big. Or both. ### What do I need? - A cheap (10$) luggage scale, model: Etekcity EL11 - Two 3D printed parts - A few screws - A few tools (M3 tap, soldering iron, glue, sticky tape) ### How is the conversion done? - Use a pair of pliers to unscrew the glued-in luggage-hook (counter-clockwise). - Open the scale (2 screws in the back). - Unscrew the PCB (3 screws). - Unscrew the load cell (2 screws). - Unsolder the load cells' 4 cables. - Solder 4 wires as long as you need them (don't go too wild, maybe 50cm max or so) to the board. Note colors and position! - Push wires through the opening in the case where the hook was. - Put PCB back, secure with the 3 screws. - Close case. - Add heat shrink tubing to the individual wires and one bigger diameter tube to keep them all neatly together. - Solder your extension wires (in the correct order of course!) to the load cell wires and shrink heat shrink tubing. - Cut M3 threads into the load cell case. - Put load cell into the case (secure each corner with a dab of glue). - Put on lid, fasten with M3 screws. - Add M8 screw, 8mm rod or what you like to act as a piston for the force sensor. ### Misc notes - STL, STP and FreeCAD files are included. If you want a different case, bigger screw holes, whatever: Feel free to modify to your heart's content! ### Cheers, Jan