Introduction

The Auto-Fold TP Point Mechanism is a mechanical device that automatically folds the tip of a toilet paper sheet into a neat triangle after each use. Inspired by the aesthetic practice of Japanese housekeeping, this device uses purely mechanical components—rollers, folding arms, and torsion springs—to reset the next sheet for a premium experience. No electronics. No batteries. Just clever engineering.

Table of Contents

• URS
• Physics
• Free Body Diagram
• Design
• BOM
• Electronics
• Code
• Modeling
• Fabrication
• Guides
• Notes
• Contact

---

URS

User Requirement Specifications

Constraints	Approach	Achieved
Size	Must fit standard TP roll mount
Depth	< 6 inches from wall
Height	< 10 inches
Width	< 10 inches
Weight	Under 1.5 lbs
Cost	<$20 in parts
Power	No electricity required	✔
Decibels	Silent to minimal mechanical clicks
Geometry	Triangular fold at paper tip	✔
Case	Wall mount or freestanding
Assemble	No tools required for install
Temperature Range	32°F to 120°F	✔

---

Physics

• Torsion Spring Force:
  τ = kθ
  Torque generated by folding arms where k is spring constant, θ is angle of rotation.
• Frictional Tension on Pull:
  Ensures roller rotates and loads mechanism without tearing paper.
• Moment Arm Calculations:
  Folding arms apply force along a line to crease paper.

---

FBD

A simplified Free Body Diagram showing:

• TP Roll
• Roller on bearings
• Folding arm A (folds right corner inward)
• Folding arm B (folds tip leftward)
• Spring force vectors
• Paper tension and tear line

(SketchBook/Instagram reel planned for this)

---

Design

See attached isometric design:

Core Components:

• Roller on shaft
• Dual folding arms with smooth edges
• Torsion spring housing
• Paper guides and crease guides
• Optional gear/cam timing control

---

BOM

Quantity	Description	Link	MOQ	Unit Cost	Total	Notes
1	Torsion Spring	Amazon	1	$3	$3	0.25″ shaft
1	Roller Axle	McMaster	1	$2	$2	1/4″ stainless rod
2	Folding Arms	Custom 3D Print	1	$0.50	$1	PLA or PETG
1	Mount Case	Laser Cut Ply	1	$5	$5	1/4″ plywood

---

Electronics

None required.
Fully mechanical design using spring-loaded motion and ratcheted roller.

---

Code

None required.
A future version could include an ESP32 with servos for a smart bidet-like experience.

---

Modeling

Parametric Model

OnShape Link

Revisions

• V1: Proof-of-concept with bent wire arms
• V2: Hinged arm + notch for better crease
• V3: Enclosed spring housing and roller bearings

---

Fabrication

• [ ] 1. Cut wood or print parts for body and arms
• [ ] 2. Install roller and spring
• [ ] 3. Assemble folding arm hinge points
• [ ] 4. Test pull-tear-refold cycle
• [ ] 5. Refine folding angles
• [ ] 6. Paint/stain housing (optional)

---

Guides

Assembly Guide

TBA (Google Docs/Youtube Link Placeholder)

Operating Guide

1. Install roll of toilet paper
2. Pull desired amount
3. Tear
4. Watch triangle auto-fold back in place

---

Notes

• Possible upgrade: magnetic creasing heads
• Consider compatibility with various paper types
• Can it self-correct if paper is torn unevenly?

---

Contact

Name	Phone	Email	Notes
James Parsons	310-999-9040	jamesparsons (at) gmail (dot) com	Creator/Designer