Introduction: The Door Handler V2
Note: This is the second version I left here for you to follow the development process. See "The Door Handler v3" for the latest version.
This is the next version of the door handler. It makes the design more complicated, but adds valuable protection lids on both sides to avoid touching the area that gets in contact with the handle. Next step will be an outside pocket holder with magnets so it must not be carried in a pocket anymore. I hope this will raise safety more so it might become a usable tool. Also the lids are not perfectly aligned yet, not covering the jaws perfectly. I will improve this too. For information about the whole development process and concerns see the previous project "The Door Handler".
There are two lids now that turn around a single axis (a fixing screw) in the front of the tool. I re-used the rubber band holder from the first version used for wrapping rubber bands around the tool's jaws for better friction. I dropped that friction enhancement part for now. The carving now holds a single rubber band connected to the lids that retracts the lids to the default position. If you push the tool over a handle the lids get pushed back allowing to grab the handle and they retract, when you pull away the tool from the handle.
You now also need one M3 screw of the length 22mm to 24mm with a counterpart nut. I currently use a much too long dummy screw for testing, but I ordered some 22mm M3 and also some M3 cap nuts which will fit better.
3D printer, PLA
One M3 screw 22-24mm and one M3 nut
Household rubber band (>60mm in loose state)
Step 1: Printing
Infill: 15% Gyroid for handler, 100% for lids
Filament: - PLA
Notes: 0.15mm height, 0.4mm nozzle
With these settings the print needs a little more than 7 meters of 1.75mm PLA filament, so the costs are not high
Step 2: Construction
Thread the rubber band into the holder carvings on both endings so that the band is under the lid stoppers and both sides of the rubber band have the same length. I use one with around 60mm length without tension. A little longer would be better because right now the tension is a bit too high. As this seems to be a standard rubber band size I tend to move the holder carvings a bit more to the back in the next version to loosen the band. It would also make it easier to thread the band into the small carvings.
Mount the lids with the lid stoppers facing the inner side of the tool. Push the rubber band with the middle part over the thumb rest into the little carving. Voila!