Concentric Coat Hook

This stylish and easy-to-print coat hook makes it easy to hang a variety of items. With large diameters and generous curves, this can hold most apparel without creasing or stretching.

The outer “cup” portion is designed to hold:

• Apparel that is hung by the collar, hood, etc.
• Heavier bags or purses

The inner “knob” portion is designed to hold:

• Apparel that is hung using a locker loop* or hanger
• Lighter bags or purses
• Other lightweight articles

The knob is provided in multiple sizes for different functions or aesthetic preferences. If you intend to use locker loops, I recommend using the small size, although the medium may work.

*A “locker loop” is the loop commonly found on dress shirts and outerwear, often at the collar or yoke, and may be on the inside or outside of the garment.

Inspiration

This model was inspired by the Duo Coat Hook, created by @SharedObjects_56029. That model did not meet my preferences, which include:

• Curved edges, which increase contact area (and decrease possible creasing/stretching)
• A concave “base”, which is partly aesthetic, but also allows a lower profile and possibility of accidentally catching items on adjacent hooks
• A slightly shallower angle on the “base", improving printability without sacrificing grip
• Trapezoidal threading, which improves thread engagement and adhesive contact area (if desired), and is more tolerant to different nozzle sizes

This was modeled completely from-scratch and, with those significant changes, does not constitute a remix. However, I did want to give credit to my design inspiration.

Printing

Layer adhesion is key. I've provided the settings I used below, but also a range of acceptable settings, in case you get better layer adhesion with different settings.

Orientation

As-oriented in the STL files, with the narrow side of the cup and wide side of the knob on the bed.

Material

I have printed this in both PETG and PLA. ABS and ASA should work as well.

Settings

• Nozzle Diameter:
  Tested: 0.4mm
  Should Work: 0.2mm - 0.6mm
• Layer Height:
  Tested: 0.2mm
  Should Work: 0.15mm - 0.35mm
• Wall Thickness:
  Tested: 1.5mm
  Should Work: ≥ 1mm
• Top/Bottom Shell Thickness:
  Tested: 0.6mm
  Should Work: ≥ 0.6mm
• Infill:
  Tested: 15% 3D Honeycomb
  Should Work: ≥ 15% anything except lightning
• Overhangs: Go slow, and be careful with cooling to maximize layer adhesion without warping. The threads are designed be more forgiving, but accuracy is important here.
• Scarf Joints: I couldn't get these to work without messing up the threads, so I wouldn't recommend using them at the moment.

Assembly

These can be mounted using screws or double-sided (VHB or 3M Command) tape.

Tip: The knob can be permanently attached to the cup using wood glue, or hot glue. This should significantly improve load-bearing capacity, and can make up for some layer-adhesion issues. Do not do this when mounting with screws unless the installation is intended to be permanent, as it will be impossible to remove without damaging the hook, wall, or both.

Using Screws

The screw holes are 4.5mm in diameter. That is equivalent to a #9 wood screw. For extra-heavy loads or usage, I'd recommend using washers as extra security against pull-through.

I highly recommend either screwing these into studs or using wall anchors. Screwing into plain drywall is a recipe for sadness.

1. Place cup in desired position and, using a pencil/pen/marker, mark the screw hole locations on the wall. It is best to orient the screw holes vertically.
2. Either:
   a. If using wall anchors, drill hole and insert anchor as directed by manufacturer.
   b. If screwing to wood stud, drill appropriate-sized pilot hole (1/8" or 3mm for #9 or 4mm screw)
   c. If screwing into drywall without anchor, re-evaluate your life choices.
   d. If attaching to some other surface (concrete, lath-and-plaster, metal studs) consult a licensed contractor/builder to determine appropriate method.
3. Screw cup to wall through modeled-in screw holes.
4. Screw knob into cup.

Using Tape

I can only recommend using 3M VHB tape or Command strips. Other adhesives may work, but have not been tested. The weakest point will be the wall finish (e.g. paint), so make sure that is durable before using this method.

1. Screw knob into cup.
2. Optional: if printed on a smooth plate, sand, scuff, or score wall-side of cup to improve adhesion.
3. Clean wall-side of cup to ensure it is free of residue.
4. Follow manufacturer's recommendations for applying adhesive and mounting to wall, making sure to apply the adhesive to cup first.