Pull-pull cord retractor (Automatikaufroller)

A automatic cord retractor with auto locking functionality and pull-pull release.

Since pictures during via ferratas are so great but always connected with the hope of not letting your phone fall (or become an oblation to the mountain spirits ;) ) i designed a small helper.
I usually attach it to my pants or backpack on the one side while the phone is connected via a cord through the phone cover.

For printing: Use any material you like to use, but I would recommend PET at least for the rotary bolt to ensure the knob can withstand some impulse from the spring. Supports are usefull for the spool. Ensure that the control curve is smooth. Avoid layerheigths >0.2mm or the small knob of the rotarybolt or the spring slit of the base are prone to break.

Assembly:

1. Thread your cord through the hole of the base and then through the small hole of the spool (see pic).
2. Cut a pice of ~1m of the spring. Bend the ends to form a V at both ends. You might to heat the material with a lighter to avoid any breakage.
3. Bring the V shaped end into the spools slit. Slide the spring into the small cut off (see pics) to bring it into the center of the spool, and thighten it.
4. Fiddle the sprint into the center of the spool
   5)Roll the cord in the opposite direction of the spring. E.g if your looking at the spool and you can see the spring, wind it in clockwise direction.
5. Mount the rotary bolt with a M3 screw into the top. You might need to grind the M3 head a little so it is flat with the rotary bolt surface. Don't tighten it to hard, the rotary bolt needs to spin quire freely. Otherwise you will experience problems with the locking behaviour.
6. Bring the spool into the base and hook the spring into the base's center rod slit.
7. Place the spool into the base and test if the spring is attached correctly by rotating the spool.
8. screw the top onto the base and ensure that the rotary bolt is somewhere in the contol curve. Again don't tighten it to hard and allow some tolerance for a free spinning spool.
9. Enjoy your new gadget.

(11) if its not working properly, try to play a little with the screw tension

Further materials needed:
Spiral spring: you can use one of an old measuring tape (Rollmaßband) or order one of these: https://www.amazon.de/gp/product/B000VCY1ZM/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

the spool is made for a max width of 13mm spring sheet. I used around 1m of a 0.1mm spring, resulting in around 1m of flexible cord length.

strap buckle (optional): i used: https://www.amazon.de/sourcingmap%C2%AE-Rucksack-Schnellverschluss-Schnalle-Schwarz/dp/B01JYDXQAO/ref=sr_1_12?__mk_de_DE=%C3%85M%C3%85%C5%BD%C3%95%C3%91&dchild=1&keywords=steckverschluss+15mm&qid=1607612087&sr=8-12

2 M3 screws :)