HeadStand — Prototype v0 Build Guide

For Joni (Chicago). Research and simulation: CJ & Luars. Rev 0 · 2026-09-30

1. The problem

Ductless mini-split indoor units hang on a steel mounting plate. Before the unit is clipped flat, the installer has to reach behind it. That's where they flare and connect the refrigerant lines, attach the drain hose, tape the bundle and connect the interconnect wire. Right now the bottom of the unit is held out from the wall in one of three ways:

• a second person holds it (paid labor sitting idle),
• a scrap block of wood or a bucket is wedged underneath (it slips, marks the wall and can drop the unit), or
• the unit's small built-in flip-out spacer, which usually gives only a few cm of room.

The hypothesis to validate in the field: installers would pay about $100–$200 for a tool that holds the unit 10–20 cm off the wall, adjustable and rock-solid, set up in under 30 seconds, with no second person.

2. How HeadStand works

      WALL │▓ steel plate
           │▓●───────────────┐   ● = unit's top hook (pivot)
           │▓ ╲   INDOOR      │
           │▓  ╲   UNIT       │
           │▓   ╲             │
           │▓    ╲____________┘
           │▓     ╲
           │[M]═════════╗U     [M] = magnetic foot on plate
           │▓  telescoping ║    U  = rubber-lined cradle that
           │▓  strut       ║         cups the unit's bottom-rear edge

1. Put the magnetic foot on the lower part of the mounting plate. It sticks there on its own.
2. Hang the unit on the plate's top hooks as usual. Let the bottom swing out.
3. Extend the strut until the cradle cups the unit's bottom-rear edge. Lock the thumb knob.
4. Both hands are free. Do the line set, drain and wiring.
5. Pull the unit's bottom out 1 cm, lift the strut away, and snap the unit flat onto the plate.

The simulation says the loads are small. A 12 kg unit held 150 mm out puts roughly 60–80 N (about 15 lbf) on the strut. So the engineering challenges are stability and speed, not strength. Don't overbuild it. The simulator lets you check any unit size and gap.

3. Target spec (v0)

4. Bill of materials — all available in the Chicago area or online

Prices are rough 2026 estimates. "HD" = Home Depot, "Menards" also stocks most hardware. McMaster-Carr ships to Chicago next day. Search their catalog with the terms given.

For the bench test rig

• ¾″ plywood, 2×3 ft, as the "wall", plus one spare universal mini-split mounting plate. HVAC supply houses sell these, or salvage one from a scrapped unit (about $15).
• A dummy "unit": plywood box 300 × 230 × 900 mm, with ballast (sandbags) to 12 kg and then 25 kg. Two lag hooks at the top-rear edge act as the unit hooks.
• Digital luggage/hanging scale (≤ 50 kg), about $12, for pull-off and magnet shear tests.
• A real used indoor unit from Facebook Marketplace/Craigslist, often $30–80 dead. This is the best test dummy.

Tools

Drill + bits (¼″, 3/8″ step bit), hacksaw or miter saw with non-ferrous blade, file/deburr tool, tape measure/calipers, 3D printer. No printer? Pumping Station: One (Chicago makerspace) and the Chicago Public Library Maker Lab at Harold Washington have printers. Craftcloud or JLC3DP print and ship the parts in about a week.

5. Build steps

1. Cut tubes. Outer tube: 200 mm. Inner tube: 220 mm. Deburr all edges.
2. Fit check. ¾″ inside a 1″ × 1/16″ wall tube leaves about 1.6 mm of play per side. Print two PETG bushings (square sleeves, 3/4″ ID, ≈0.87″ OD, 15 mm long) and press one into the mouth of the outer tube. If it's still loose, wrap the inner tube with a layer of UHMW tape. Target: slides by hand, no wobble.
3. Lock. Drill a hole in one face of the outer tube, 15 mm from the open end, sized for the rivnut. Set the ¼-20 rivnut. Thread in the star knob. It clamps against the inner tube. Add a small printed pad under the knob tip so it doesn't gouge the tube.
4. Magnetic foot. Print a foot cap (40 × 40 mm face, plugs into the outer tube's closed end). Bolt the pot magnet through the center so its face sits 0.5 mm proud of the plastic. Stick 1/8″ neoprene around the magnet so the foot won't mark the wall if it touches drywall instead of the plate.
5. Cradle. Print a U-cradle, 60 mm wide, 15 mm deep channel, 5 mm walls, with a stem that plugs into the inner tube. Secure it with an M4 screw. Line the channel with neoprene. Printing tip: lay it flat with the channel facing up, 4 walls, 40% gyroid infill.
6. Depth scale. Engrave or mark every 10 mm on the inner tube so installers can repeat a setting.
7. Weigh the tool (target < 500 g) and photograph every part, with dates. Keep the photos as invention records.

6. Test plan

A. Bench (before any real install)

B. Field (the test that decides everything)

1. Find 3–5 Chicago-area residential HVAC installers, ideally small non-union shops doing mini-splits and heat pumps (IL heat-pump rebates keep them busy). Leads: Facebook groups, r/HVAC, supply houses (Johnstone, Ferguson, Carrier Enterprise counters early in the morning).
2. First watch one install without the tool. Time the "someone holds the head" step and note how they solve it today.
3. Then let them use HeadStand on the next install. Time it again.
4. Ask: "Would you buy this? At $99? $149? What would you change?" Do they take out a wallet, or just say "cool"? That's the real signal.
5. Film the problem (with permission). CJ can use it for content once the provisional is filed.

Kill criteria

• Most installers say the built-in spacer or a block of wood is "good enough", or
• the held step is under about 10 minutes and no one would pay ≥ $60.

If either is true, stop. Take what you learned back to the Round 2 list (next candidates: condensate/drain install aids, drywall overhead holding).

7. Engineering notes from the simulation

• The strut force is F = W·xc / (H·cos θ). W is the unit's weight, x_c is the horizontal distance from the hook to the unit's center of mass, H is the unit's height, and θ = asin(gap / H).
• Aluminum ¾″ tube has a buckling safety factor in the hundreds. Strength isn't the risk. The risks are side slip, the magnet sliding and the wall marking. Test those.
• The plate hook sees the same horizontal pull as the strut force (≈ 15–35 lbf). That's well within what the unit's top hooks already carry when a person holds it out.
• v1 ideas once validated: a spring-loaded self-extending strut; a second "arm" with hose/tape holder; an injection-molded foot and cradle (≈ $3–6k tooling at a US molder, only after 100+ pre-orders).

8. Rough unit economics (to check later)

9. IP housekeeping

• Keep dated sketches, CAD, photos and test logs, with a note of who contributed which idea. The inventors are the humans who conceived the mechanism. AI-assisted research and simulation is fine as a tool.
• Before any public demo, sale or social post showing the mechanism, file a US provisional patent. Book one consult with a Chicago patent attorney first.
• Assign inventions to the team's LLC so all three founders are covered.