Small improvements

Upgrade 21.07.2020

Changes:

- Longer guide v2 (3 mm)
- Changed hole for printed screw to hole for M5 nut
- Spring cap (for spring 8mm OD, 4mm ID) between M5 screw and spring
- Reworked Knob (two parts, snug fit, alignment marks)
- You will need M5x20 bolt with hexagonal head and M5 hexagonal nut

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I have improved these details.

- Bigger knob and threads
- Longer guide
- Added threads for M6 fitting
- The hole for filament between fitting and PTFE tube is wider
- Added hole for zip tie on the corner of the base

Reasons for remix

- The turning of knob was not comfortable and sometimes threads slipped
- Guide was too short for green spring
- Fitting was loose
- After printing the hole for filament between PTFE tube and fitting was too small
- No option for securing the cable