The Door Handler V3

This is the third version of the Door Handler. For previous development steps see my instructables "The Door Handler" and "The Door Handler v2".

Improvements:
- The lids are a bit larger and fit better over the jaws now.

- The lid's rubber band slots moved a bit to the back to reduce tension when using a 60mm rubber band.

- Hot glue is used on the inner of the jaws to add a smooth and grippy surface.

- Added 3D objects for a pocket holder. Four 6 x 2.8mm Neodym magnets are required for the pocket holder and the handler itself.

- Added left hand and right hand version so you can wear it on both sides.

I consider this the first version which might be really usable. Though I don't feel the urge to make the design more complicated a version with UV integrated LEDs roams in my mind. Maybe I will go for it the next days.

Aside the 3D printed parts you need:

- one household rubber band 60mm

- one M3 screw 22mm or 23mm

- one M3 nut (I now use an M3 cap nut)

- four 6 x 2.8 mm Neodym magnets

Print all the parts, which is one handler (left or right), one handler holder (left or right), both lids and one pocket holder clip. Choose either left hand or right hand version for the handler and the handler holder.

Print settings:

- 0.4 mm nozzle

- 0.15 mm layer height

- 15% Gyroid infill

- a brim is recommended

- I used PLA for these prints. I'm not the biggest fan of ABS, but in this case this and PETG would be the better material to use because of the chemical resistance. ABS and PETG can be cleaned with ethanol without worrying that the material becomes brittle.

Add hot glue to the inner area of the jaws. Try to make a smooth grip surface.

Thread the rubber band trough the holes on both lids as shown in the picture.

Align the band over the thumb rest, then move the lid screw holes over the mounting hole of the front jaw. Attach the screw. To avoid that the nut loosens though usage you can put some glue on the screw/nut junction.

Push two magnets into the holes of the handler holder and two magnets into the associated holes of the handler grip.

IMPORTANT NOTE: Check the polarity of the other two magnets before pushing them in, so that both magnet pairs attract each other properly! There is a trick you can use that makes placing the magnets much easier. First glue the magnets to the handler, then clip the opposite magnets of the holder on their counterparts on the handler. Add some (hot) glue to the holes in the handler holder, then take the handler and push it into the holder to place the magnets. Don't use too much glue to avoid sticking both magnets together.

Hot glue the handler holder to the holder clip.

Attach the handler holder to either your left or right pocket depending which version you printed.

Here are two pictures on how to use the handler on a door handle. The lids get pushed up when you place the handler over a handle. You can then push down the handle and then push the door back or pull it.

PLA is not the best material to clean: the printed surface is not totally even and although you can rinse it with boiled water for some seconds without a problem, you can't cover it with it. The PLA will get soft in a short time due to the heat therefore a dish washer is also no option. Spraying it with ethanol is the most reasonable solution right now, but note that alcohol tends to make PLA brittle over time. Maybe coating the tool with some protective layer like spray paint could also help. If you have ABS or PETG, use these because both of them are chemical resistant to ethanol. You could also try to CNC a version with a better material.

Important Note about Stability and Print Settings

For the prints I used 15% filling with the wonderful Gyroid pattern and it seems to be quite stable though I DID NOT TRY OUT THE FORCE IT TAKES TO BREAK IT. You maybe might want to experiment with a higher filling density. The print nozzle was 0.4mm and layer height was 0.15mm. The whole set of handler, holder, clip and lids with the mentioned settings needs a little more than 11 meters of 1.75mm filament (~33 grams).

I would have loved to add a UVC LED for instant sterilization, but they're still too expensive (about 30-40$ for one). Also the efficiency is quite bad, only a fraction of the power in converted to UVC radiation, the rest (~90%) dissipates as heat.

I published all door handler versions under the GNU GPL for everyone to copy, use, develop and share. You find the repo here. Peace and love.