Lian Li Vector V100-style 3x 3.5" HDD floor-supported rack
v0.5 - separate bolt-on fan-brace revision

This revision is based on v0.4 but changes the fan-side support into a separate printed part.
It also bakes in the user parameter changes:

  base_bar = 12.0 mm
  base_h   = 8.0 mm

Design intent
-------------
- 3x 3.5" HDDs stacked vertically.
- Small 101.6 mm x 26.1 mm HDD ends face the side fans.
- Four adjustable M5 leveling feet carry the drive/rack weight.
- Side fan screws provide lateral stability only.
- The fan brace is now a separate bolt-on stabilizer rather than part of the main rack.
- The base uses triangulated bars between each pair of foot bosses and the middle bottom crossbar.

OpenSCAD part selector
----------------------
At the top of the SCAD file, change:

  part = "assembly";

Options:

  part = "assembly";          Preview rack + separate fan brace + mock drives.
  part = "rack";              Export/print the main HDD rack only.
  part = "fan_brace";         Export the separate fan brace in installed orientation.
  part = "fan_brace_print";   Export the separate fan brace laid flat for easier printing.
  part = "test_coupon";       Test grommet slot and M5 foot boss/nut pocket.
  part = "mock_drives";       Shows only the drive/cable envelopes.

How the separate fan brace attaches
-----------------------------------
The main rack has four outside receiver lugs on the fan-facing side.
The separate fan brace has:

- Four vertical slots matching a 120 mm fan-hole pattern.
- Four M4 rack-side bolt holes matching the receiver lugs.

The intended installed stack-up is:

  side fan bracket / fan frame
      -> rubber washer
      -> separate printed fan brace
      -> M4 bolts through brace into rack receiver lugs
      -> optional captive M4 nuts in rack-side lug pockets

The fan brace should be tightened after the four feet are adjusted.
Do not use the fan-brace screws to lift or preload the rack; they are only there to stop tipping/sliding.

Suggested hardware
------------------
HDD mounting:
- 6-32 UNC HDD screws.
- Rubber/silicone grommets or rubber washers for isolation.
- Metal washers under screw heads if needed.
- Keep screw penetration into the HDD shallow; roughly 3 mm is a safe target unless your drive manual says otherwise.

Feet:
- 4x M5 screws/bolts for leveling feet.
- 4x M5 nuts for captive pockets.
- 4x rubber feet/pads/caps.
- Optional M5 locknuts or removable threadlocker.

Separate fan brace:
- 4x M4 bolts/washers from brace to rack receiver lugs.
- Optional M4 nuts in the receiver lug pockets.
- 2-4x fan-mount screws or M4 hardware through the fan slots.
- Rubber washers are recommended between fan brace and case/fan bracket.

Important install order
-----------------------
1. Print/test-fit with no HDDs installed.
2. Put the rack in the case.
3. Adjust the four M5 feet so the rack is solid and level enough on the lower floor/angled panel.
4. Bolt the separate fan brace loosely to the rack receiver lugs.
5. Align the brace's vertical fan slots to the side fan mounting holes.
6. Snug the fan-mount screws lightly.
7. Install HDDs and 90-degree SATA power/data cables.
8. Recheck that the rack weight is still on the feet, not hanging from the fan mount.

Parameter notes
---------------
Likely tuning variables:

  base_bar             = 12.0;
  base_h               = 8.0;
  cable_channel        = 18.0;
  air_gap              = 25.0;
  brace_lug_w          = 10.0;
  brace_lug_y          = 9.0;
  brace_mount_z1/z2    = rack_h/2 +/- 18.0;
  fan_lower_slot_z     = 30.0;

If the fan holes don't line up after the rack sits naturally on its feet, adjust fan_lower_slot_z first.
If the brace-to-rack bolts are awkward to reach, adjust brace_mount_z1 and brace_mount_z2.

Print notes
-----------
Recommended material:
- PETG, ASA, ABS, or PC.
- Avoid PLA inside the case.

Main rack:
- Use strong perimeters/walls.
- Consider 35-50% infill or equivalent high-strength settings around bosses/feet.
- Orient so the base and foot bosses print cleanly.

Fan brace:
- Print flat using part = "fan_brace_print" or rotate it flat in your slicer.
- More perimeters are better than high infill for this thin stabilizer.
- It is a lateral brace, not a structural hanging bracket.
