LogiTech MX Mechanical Keyguard for Parkinsons and Tremors

# STEADYWELL – clip-on keyguard with swappable key blockers & finder rings for Logitech MX Mechanical

**A keyguard you can tune to one person's hands.** STEADYWELL clips over the MX Mechanical and puts every key at the bottom of its own shallow well. You can rest your hand on it without typing, and a shaky finger drops onto the key it was aiming for instead of the one next to it.

Small snap-in inserts let you switch individual keys off, or make them easy to find by touch and colour. You can change the setup in seconds, with no tools.

Built from the official MXMecha_Dummy.step starter file from Logitech's Official MX Keyboard CAD Templates.

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## Who it helps

STEADYWELL is for people who have trouble hitting one key at a time, including:

- Hand tremor. For example Parkinson's disease, essential tremor or multiple sclerosis. Tremor turns one keypress into several and makes fingers land on neighbouring keys.
- Reduced fine-motor control. For example cerebral palsy, stroke, brain injury or ALS. These make it hard to lift the hand off the keys between presses, so resting the hand causes accidental typing.
- Typing with a mouthstick, head pointer or typing stick. The wells guide the tip onto the key and stop it skating across the keyboard.
- Low vision. High-contrast halo rings and tactile blockers help find important keys and avoid unwanted ones.

## What it does

- A flat resting surface. The guard floats 1.4 mm above the keycaps, so the hand can lean anywhere on it without pressing a key. Anchoring the hand is one of the most effective ways to steady a tremor while typing.
- Each key is a well. Every key sits at the bottom of a 6 mm-deep opening with a 45° lead-in. The finger or stylus is guided to the centre of the key and can't slide onto its neighbours.
- Blockers (red). Snap one into a well and that key is switched off. The blocker sits flush with the surface and has an engraved X you can feel. Typical uses are Caps Lock, the Windows/Start key, Menu and Insert, the keys that cause the most "what just happened?" moments. Every blocked key also becomes extra resting space.
- Halos (yellow or any contrasting colour). A raised ring around a key makes it easy to find by touch and by sight. Typical uses are Esc, Enter, Backspace and the F/J home keys.
- Tunable over time. Inserts come in all 8 key sizes on the board and can be moved or removed in seconds. A therapist, carer or the user can adjust the layout as needs change. This matters for progressive conditions.

## How to use it

1. Clip the guard on (see Assembly below).
2. Rest the heel of your hand or your fingers on the flat top.
3. To type, press a fingertip, knuckle or stylus down into the well of the key you want. Keys work normally through the openings.
4. Start with no inserts, and notice which keys get hit by accident and which are hard to find. Add blockers to the first group and halos to the second.
5. Lift the guard off anytime to type normally.

> Tip for tremor users: keep the side of your hand in contact with the guard while typing. The guard carries the weight of your hand, and your fingers only have to travel down into one well.

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## Printing

**Parts list:**

| Part | Qty | Material | Notes |
|---|---|---|---|
| guard_A_left | 1 | PLA / PLA+ | 142 × 137 × 30 mm |
| guard_B_middle | 1 | PLA / PLA+ | 169 × 137 × 30 mm |
| guard_C_right | 1 | PLA / PLA+ | 146 × 137 × 30 mm |
| blocker_*u | as needed | PETG | 8 sizes |
| halo_*u | as needed | PETG | 8 sizes, contrasting colour |

- Bed size: every part fits a 180 × 180 mm bed, including Prusa MINI and Bambu A1 mini.
- Orientation: all STLs are pre-oriented. Print them as supplied; the flat top face goes on the bed.
- Guard settings: 0.2 mm layers, 3 walls, 15–20 % gyroid infill, 5 top and bottom layers.
  - No supports are needed.
  - The four small rear hook lips are a short, steep overhang. If your printer droops there, add tree supports under the lips only.
  - Use PLA or PLA+. It's stiffer than PETG, and stiffness keeps the guard from flexing onto the keys.
  - A textured PEI sheet gives the resting surface a pleasant grip.
- Insert settings: 0.12–0.16 mm layers, 100 % infill, no supports.
  - Use PETG, because the snap arms need to flex.
  - Halos have a small bed contact area, so use a brim or glue stick if they lift.

**Suggested starter kit:**

- Blockers: 1× 1.75u (Caps Lock), 2× 1.25u (Win, Menu).
- Halos: 3× 1u (Esc, F, J), 1× 2u (Backspace), 1× 2.25u (Enter), 1× 2u vertical (Numpad Enter).

**Which insert fits which key:**

| Size | Keys |
|---|---|
| 1u | Letters, numbers, F-keys, Esc, nav cluster, arrows, most numpad keys |
| 1.25u | Ctrl, Start/Win, Alt, Fn, Menu |
| 1.5u | Tab, \ |
| 1.75u | Caps Lock |
| 2u | Backspace, Numpad 0 |
| 2u vertical | Numpad +, Numpad Enter |
| 2.25u | Left Shift, Enter |
| 2.75u | Right Shift |

## Hardware

**None.** STEADYWELL is 100 % printed. It needs no screws, magnets, rubber bands or heat-set inserts.

One optional extra: a drop of CA (super) glue in each dovetail, if you want the three guard pieces joined permanently.

## Assembly (about 1 minute, no tools)

1. Join the three pieces.
   - Stand A, B and C upright on a table, top face up. Slide B straight down onto A's two dovetail tabs, then slide C down onto B's three tabs.
   - The joint between A and B follows the natural left-hand/right-hand divide of touch typing, and runs through key openings rather than through the thin walls between them.
2. Hook the back.
   - Hold the joined guard with its front edge tilted up. Hook the four rear lips under the back edge of the keyboard.
   - The hooks sit clear of the USB-C port and power switch.
3. Lower the front. Rotate the front down until the skirt drops over the front edge of the keyboard. The guard is now locked: lifting the front only pushes the hooks further under the keyboard.
4. Add inserts. Press a blocker or halo into any well until it clicks.
5. Removing things.
   - Guard: lift the front edge, then unhook the back.
   - Inserts: lift the guard off and push the insert out from underneath.

## Non-destructive

STEADYWELL never opens, drills or permanently changes the keyboard:

- It clips over the case and holds on with four hooks under the rear edge.
- It uses no adhesive and no fasteners.
- It rests only on the flat rim around the keys.

*Modifications are done at the user's own risk. Logitech does not provide support for third-party add-ons, as per Logitech's legal disclaimer.*

## Editable source files

- STEP: the full assembly, positioned exactly over the official MX Mechanical model, plus each guard piece and each insert. It opens in Fusion 360, Onshape, FreeCAD, SolidWorks and others.
- generate.py: the fully parametric generator, written in Python with CadQuery.
  - It reads key positions, keycap shape and case outline directly from Logitech's STEP file and rebuilds every part.
  - You can adjust well depth, opening size, clearances, hook positions and insert fit. For example, use deeper wells for mouthstick users, or bigger openings for large fingers.
  - Install with pip install cadquery trimesh shapely manifold3d, then run python generate.py MXMecha_Dummy.step out/.

## Tested fit (checked digitally against the official model)

- No contact at rest. The guard doesn't touch the keyboard with keys at rest, pressed to actuation, or fully bottomed out.
- Allows for wobble. There is still no contact with every keycap shifted 0.5 mm in any direction.
- Clearances:
  - 1.4 mm above the keycaps
  - 0.8 mm around their sides
  - 0.3 mm around the case
- Inserts. They don't touch the keycaps, and their snap barbs lock under the guard's plate.

Because the official file is a simplified model without rubber feet, please share a make if you fit it to a real keyboard. Feedback on fit helps everyone.

**Tuning tips:**

- If the inserts are too tight or too loose, change fit (default 0.15 mm) and regenerate.
- If you print the guard in PETG, raise c_top to 1.8 mm for extra clearance.

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## Tags

#Keyguard #Tremor #LowDexterity #FineMotorControl #Parkinsons #EssentialTremor #CerebralPalsy #MultipleSclerosis #MouthStick #HeadPointer #TypingStick #LowVision #HighContrast #TactileMarkers #KeyBlocker #ClipOn #NoTools #NoHardware #NonDestructive #MXMechanical #Logitech #AssistiveTechnology #Accessibility