I-Wood system reference

EngineeringStandards

A modular family of wood profiles organized around three nominal size classes and a common Hill-and-Valley geometry.

Preliminary specificationRevision 2026-09-10

01 / 09

The I-Wood interface concept

Plain. Hill. Valley.

What distinguishes I-Wood is the addition of two complementary surface geometries—Hill and Valley—to an otherwise conventional wood component. These shallow profiles transform timber from raw stock into a repeatable part of a joint, allowing adjoining components to locate, engage and align through their own geometry.

The principle is related to a tongue-and-groove joint, but incorporates designed-in tolerance along the profiled surfaces. This provides limited accommodation for the natural dimensional movement of wood caused by changing moisture conditions while maintaining positive registration between components.

Because the Hills and Valleys are deliberately shallow, they can read as architectural detailing rather than purely functional machining. The profiles can be produced using relatively simple router tooling, from small workshops through to economical production-scale manufacturing.

When assembled, the complementary angled surfaces guide the components toward their shared centre. This self-centering action improves alignment, while engagement across several profiled faces distributes forces through the joint and contributes to a secure mechanical connection.

Hill and Valley surfaces interlock and self-align.

Plain

Flat, unmodified face.

Hill

Raised profile intended to mate with a Valley.

Valley

Recessed profile intended to mate with a Hill.

Hill and Valley surfaces interlock and self-align, creating positive registration between adjoining components without additional fixtures.

02 / 09

The geometric foundation

Three relationships define the system.

The standard continues with a proportional rule set. Every size class scales from the same Hill-and-Valley width, depth, and side-angle relationships.

½ Width40 mm ÷ 2 = 20 mm

Hill / Valley width

In this Medium-class example, every Hill and Valley is half the 40 mm component width: 20 mm.

⅛ Width40 mm ÷ 8 = 5 mm

Hill / Valley depth

The same 40 mm component uses a 5 mm Hill and Valley depth—one eighth of its width.

45°Same angle on every side

Hill and Valley side angles

Each sloping side of every Hill and Valley uses the same 45° geometry.

03 / 09

Three size classes

One family at three compatible scales.

The dimensioned view shows how the 20 mm, 40 mm, and 80 mm profiles scale together and permit selected components to interface across sizes.

Three C profiles showing 20, 40, and 80 millimetre nominal sizes — The C profile at 20 mm, 40 mm, and 80 mm demonstrates scale progression and cross-scale compatibility.

Metric and imperial compatibility

For I-Wood, 20 mm = 3/4 in, 40 mm = 1 1/2 in, and 80 mm = 3 in. The Hill-and-Valley fit is designed to accommodate the small stock difference between the two systems.

Code	Metric	Imperial
IW-S	20 mm	3/4 in
IW-M	40 mm	1 1/2 in
IW-L	80 mm	3 in

Lettered I-Wood profiles assembled into a multi-face component — Lettered I-Wood profiles demonstrate how the shared geometric system can organize components across multiple faces and size classes.

H and U profiles illustrate the cross-size relationship: each smaller class locates within the Valley section of the next larger class.

Cross-size Valley registration

Each smaller class locates within the next larger Valley.

Because every Valley is one half of its component width, the system creates two exact cross-size relationships. A 20 mm Small component matches the 20 mm Valley of a 40 mm Medium component. A 40 mm Medium component matches the 40 mm Valley of an 80 mm Large component.

IW-S · 20 mm=IW-M Valley · 20 mmIW-M · 40 mm=IW-L Valley · 40 mm

This lets selected components from adjacent size classes seat laterally within the same geometric system, extending alignment and assembly options without introducing a separate interface standard.

04 / 09

Groove geometry

Dimensions scale without changing the rule.

Standard dimensions

Size	Component width	Hill / Valley width	Hill / Valley depth
IW-S	20	10	2.5
IW-M	40	20	5
IW-L	80	40	10

All values shown in millimetres. All Hill and Valley side angles are 45 degrees. This dimensional progression also demonstrates cross-scale compatibility.

Three I-Wood profiles with Hill-and-Valley width and depth dimensions — Hill-and-Valley width and depth scale in direct proportion to component width, allowing selected profiles to interface across sizes.

05 / 09

Profile catalogue

Dimensioned profiles in one consistent language.

Each code identifies one profile. The catalogue uses supplied dimensioned end-view drawings so shape, scale, and Hill-and-Valley geometry can be read together.

IW-S · 1×20 mm / 3/4 inSmall reference size

×2 →

IW-M · 2×40 mm / 1.5 inEvery linear dimension is twice IW-S

×2 →

IW-L · 4×80 mm / 3 inEvery linear dimension is twice IW-M

Uniform scaling doubles every linear dimension from Small to Medium, then doubles it again from Medium to Large. One dimensioned profile drawing can therefore define the same profile in all three standard sizes.

Directional scaling

A profile may also be extended along one principal axis without enlarging the other. Each mating face keeps the Hill-and-Valley proportions assigned to that face, preserving system compatibility while changing only the required width or height.

2C4 · Width-only extension · 80 × 40 mmWidth increases to 80 mm while height and the side-interface geometry remain on the 40 mm standard.

4C2 · Height-only extension · 40 × 80 mmHeight increases to 80 mm while width remains 40 mm; the side-interface geometry follows the 80 mm standard.

Current profile catalogue

The drawings below show the most common profiles in the IW-M medium size class, with a nominal 40 mm component width. The proportional rules above define the corresponding IW-S and IW-L versions; separate drawings are only needed for directional variants. Select any drawing to inspect its dimensions.

AAM 40 mm profile drawing

CCM 40 mm profile drawing

CrnCrnM 40 mm profile drawing

DDM 40 mm profile drawing

HHM 40 mm profile drawing

IIM 40 mm profile drawing

OOM 40 mm profile drawing

UUM 40 mm profile drawing

VVM 40 mm profile drawing

WWM 40 mm profile drawing

Example of I-Wood component labeling

Every component code reads from left to right in the same four-part order: profile, size class, finished length, and end treatment. Hyphens separate the profile-and-size identifier from the length and end treatment.

CM-120-SS

CC profile

MMedium size class

120Length in centimetres

SSSquare ends at both ends

CM-120-SS · Profile + Size – Length – End treatment

More component labeling examples

These finished components demonstrate how the identification code appears across different profile, length, and end-treatment combinations.

I-Wood component labeled AM-60-OO — AM-60-OO

I-Wood component labeled CM-120-RR — CM-120-RR

I-Wood component labeled DM-120-SS — DM-120-SS

I-Wood component labeled JM-60-HS — JM-60-HS

06 / 09

Manufacturing basis

From proportional geometry to repeatable production.

Complementary Hill and Valley router bits — Complementary Hill-and-Valley router bits reproduce the mating profile geometry shown in the drawings below.

Valley-form relationshipThe complementary cutter geometry corresponds to the recessed Valley surface.

Hill-form relationshipThe cutter geometry corresponds to the raised Hill surface of the finished profile.

01Prepare and identify the blank

Size stock for the selected component, shape, and surface treatment. The recommended standard length is 1200 mm, approximately 4 ft.

02Allow for the Hill

Additional blank material: 2.5 mm, 5 mm, or 10 mm for IW-S, IW-M, or IW-L.

03Match the bit to the drawing

The routing bits reproduce the Hill-and-Valley dimensions shown in the profile drawing. The supplied diagrams document 45-degree routing, Hill-bit, and Valley-bit geometry below.

04Why the 45-degree bit is long

At a 45-degree angle, the cutting path across the component is longer than it would be in a straight, square cut. The extended cutting edge ensures that enough of the knife remains in contact to cut completely across the component in one continuous pass.

05Align the centres

When the workpiece centre aligns with the router-bit centre, the intended routed profile is produced.

Dimensioned Hill routing-bit and workpiece geometry — **Hill bit geometry**Dimensioned Hill-form routing setup · supplied dimensioned routing geometry

Dimensioned Valley routing-bit and workpiece geometry — **Valley bit geometry**Dimensioned Valley-form routing setup · supplied dimensioned routing geometry

45-degree routing geometryBit, workpiece, profile, and clearance dimensions · supplied dimensioned routing geometry

07 / 09

Adaptable workshop tooling

One jig profile. Many component geometries.

I-Wood cutting and drilling jigs use the dedicated Jig profile as a configurable locating body. By setting dimension X to the target workpiece, the same jig principle can be adapted to hold virtually any I-Wood profile securely and repeatably.

Jig profile · adjustable dimension XDimension X defines the clear span between the locating faces. It is selected to match the component being held.

System principle

The fixture is derived from the workpiece.

The Jig profile provides the body of the fixture. Changing dimension X changes the receiving space without changing the basic locating principle, allowing purpose-built jigs to be produced for different I-Wood sizes and profile shapes.

X: Clear holding dimension matched to the selected I-Wood component.
Registration: The component seats against the jig’s locating faces so the tool guide remains referenced to the workpiece.
Repeatability: Once configured, the jig reproduces the same cut or drilling geometry across multiple components.

Cutting jig

Pre-cut slots establish the cutting plane.

The workpiece is seated in the jig and the saw runs through the selected guide slot. Prepared slots establish repeatable cuts at 90°, 22.5°, 30°, and 45°, while the Jig profile holds the component in registration and constrains the blade path.

Drilling jig

Pre-drilled guides establish position and angle.

The drill bit follows a prepared guide hole in the jig body, controlling its entry point and drilling direction relative to the workpiece. A drilling jig can be configured with guides at 90°, 22.5°, 30°, and 45°, then sized through dimension X to suit the required I-Wood profile.

Shared tooling logic

Both jig types separate setup from repetition: profile selection and dimension X establish the fit; the prepared slot or guide hole establishes the tool path.

Jig assembly

Four matching members create one continuous fixture.

The dedicated Jig profile is repeated and rotated around the work zone. Its shaped faces establish how adjoining members meet, while the enclosed opening becomes the receiving channel for the component and its guided operation.

01 · Repeatable member

Begin with the Jig profile.

Each side of the fixture is derived from the same purpose-built profile. Repetition keeps the locating geometry consistent around the assembly.

Exploded arrangement of four I-Wood Jig profiles around a square work zone

02 · Orientation

Position four members around the work zone.

The profiles are rotated into their required sides so the shaped edges approach one another and the central working space remains open.

Four I-Wood Jig profiles assembled into a square fixture

03 · Completed frame

Close the assembly into a continuous jig body.

With the four members brought together, the outer frame provides the fixture body and the centre opening defines the controlled receiving channel.

08 / 09

Closed-form assemblies

One interface. Many closed forms.

Hill-and-Valley profiles can be repeated and rotated around a shared centreline. As each Hill registers with the adjoining Valley, the individual members close into square, hexagonal, octagonal, and related polygonal sections.

A family of hollow I-Wood posts assembled from repeating Hill-and-Valley profiles — **A common interface, applied around the perimeter**Changing the profile combination and number of repeated members changes the completed section while preserving the same locating principle at each joint.

How the geometry closes

The joint becomes the shape.

Each longitudinal edge forms part of the same complementary interface. When the members are brought together in sequence, their mating faces locate one another and establish the perimeter of the finished assembly.

Repeat: Use a consistent member around the section so every adjoining face follows the same assembly logic.
Rotate: Orient each member toward the shared centreline to establish the required four-, six-, or eight-sided form.
Close: Engage the final Hill-and-Valley pair to complete a continuous hollow or closed section.

Four I-Wood members forming a hollow square post — 04 membersSquare hollow sectionA compact four-sided arrangement for rectilinear posts, legs, columns, and casings.

Six I-Wood members forming a closed hexagonal post — 06 membersHexagonal closed sectionA six-sided assembly that demonstrates how repeating faces resolve around a central axis.

Six I-Wood members forming a hollow hexagonal post — 06 membersHexagonal hollow sectionThe central void can reduce material and provide a protected route for wiring or other services.

Eight I-Wood members forming a hollow octagonal post — 08 membersOctagonal hollow sectionAdditional sides create a more rounded architectural expression while retaining repeatable joints.

Potential applications

From furniture-scale parts to architectural elements.

These assemblies can inform pillars, posts, table legs, lamp columns, hollow decorative casings, and beam-like components. The geometry defines how the parts locate and close; wall thickness, reinforcement, loading, fastening, and code compliance must be engineered for the intended application and region.

09 / 09

Development status

Clear about what is defined—and what comes next.

Defined in this preliminary specification

Three metric and imperial size classes
Proportional Hill-and-Valley width and depth
45 degree Hill and Valley side angles
Cross-scale compatibility
Self-aligning Hill-and-Valley surfaces
Square, hexagonal, and octagonal closed-form assembly principles
Dimensioned profile and routing geometry
Adaptable cutting and drilling jig principles
Component identification pattern

Regional standards and future documentation

Structural capacity and code compliance are region specific
Requirements should be sourced from the relevant local authorities
I-Wood intends to provide code specifications in due course
Profile face classifications and release status remain to be verified before publication