Engineering Standards

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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.

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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.

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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.

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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.

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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

VHVHM 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-40-OO — AM-40-OO

I-Wood component labeled CM-40-RR — CM-40-RR

I-Wood component labeled DM-40-SS — DM-40-SS

I-Wood component labeled JM-40-HS — JM-40-HS

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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.

Two-bit production system

Two complementary cutters generate the complete I-Wood profile language.

The Hill-form and Valley-form router bits establish the two mating surface conditions at the centre of the I-Wood system. Applied to different faces, orientations, size classes and lengths, they produce every standard Hill-and-Valley interface from which the profile catalogue, joints and larger assemblies are developed.

The breadth of the system comes from recombining consistent geometry—not from requiring a separate cutter for every component. Frames, closed forms, furniture, tools and architectural elements can therefore be derived from one interoperable family of routed profiles. Conventional workshop operations complete the component wherever plain faces, end cuts, drilling or finishing are required.

The two complementary I-Wood router bits surrounded by the profiles, joints, frames, furniture, tools and architectural forms derived from the system — **One tooling principle · an open field of outcomes**The two central cutter geometries establish a common interface that can be repeated and recombined across the full I-Wood system.

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

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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 is measured across the receiving Valley, between the two 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.

Configured receiving sizes

The same four-member jig scales to different workpieces.

Dimension X is set when the Jig profiles are produced. Changing that clear receiving dimension creates a fixture for the selected component while preserving the same enclosing form, locating faces and working principle. The examples below show dedicated jigs for 2C2, 2C4 and 2C8 components.

Four I-Wood Jig profiles assembled around a 2C2 receiving opening — **2C2 jig**Compact receiving opening configured for the 2C2 component.

Four I-Wood Jig profiles assembled around a 2C4 receiving opening — **2C4 jig**Intermediate receiving opening configured for the 2C4 component.

Four I-Wood Jig profiles assembled around a 2C8 receiving opening — **2C8 jig**Larger receiving opening configured for the 2C8 component.

Guided cutting operation

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.

Guided drilling operation

Two I-Wood C components aligned for assembly with a drilled dowel connection — Result · aligned dowelled connection

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.

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Repeatable corner geometry

Square, hexagonal, and octagonal corners—made from controlled cuts.

A closed frame is defined by a repeated change of direction. I-Wood turns that geometric requirement into a repeatable workshop operation: the profile is positively located, each mating end is cut to a controlled angle, and the dowel positions are established from the same reference faces.

A family of I-Wood corner connections shown at several angles before assembly — **One corner-making principle, applied at several angles**Accurately prepared mating ends and aligned dowel locations allow the same profiled members to resolve a range of frame and polygon geometries.

Square90° finished cornerTwo equal 45° mitres close the corner.

Hexagon120° internal cornerTwo equal 30° mitres establish the six-sided form.

Octagon135° internal cornerTwo equal 22.5° mitres establish the eight-sided form.

Jig-assisted machining

The fixture converts angle selection into repeatable work.

The cutting jig holds the I-Wood profile against consistent locating faces while its prepared slots guide the saw through the required cutting plane. For the three common closed forms, the operator selects the 45°, 30°, or 22.5° mitre guide rather than laying out every component independently.

After cutting, the drilling jig references the same profile geometry to control dowel-hole position and direction. Matching holes bring the prepared ends into registration during assembly, reducing accumulated error as the corners are repeated around the frame.

Two profiled I-Wood members prepared for a 45-degree corner relationship — 45°**Directional corner study**A shallow change of direction illustrating the system’s angular range.

Two profiled I-Wood members prepared for a 60-degree corner relationship — 60°**Hexagonal direction change**The six-part turn is established by consistently prepared mating ends.

Two profiled I-Wood members prepared for a 90-degree square corner — 90°**Square corner**Equal mitres and aligned dowels produce a clean right-angle connection.

Two profiled I-Wood members prepared for a 120-degree internal corner — 120°**Hexagonal internal corner**A controlled 120° internal relationship closes naturally into a six-sided form.

Precision accumulates

In a polygonal frame, a small error at one joint is multiplied around the perimeter. Referencing every cut and drilling operation to the same jig geometry keeps the repeated corners consistent, helping the final joint close accurately.

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Profiled corner reinforcement

Knees and elbows lock the corner into one working joint.

Knees and Elbows bridge adjoining components at a change of direction. Their triangular form braces the corner against racking, while complementary Hill-and-Valley surfaces positively locate the reinforcement on the components it connects.

Joint action

Geometry reinforces the connection in more than one direction.

Rather than relying on a single fastener line, the profiled reinforcement engages the adjoining members across broad mating faces. The triangle transfers forces between the two components and reduces their tendency to open, twist or move out of square.

When the profiles are fully seated and the assembly is secured by its specified fastening or bonding method, the result is an exceptionally robust corner connection. Final structural capacity remains dependent on material, dimensions, grain direction, workmanship, fastening and the requirements of the intended application.

End views comparing the full component-width Knee with the reduced-width Elbow — **Two reinforcement depths, one locating principle**The Knee extends through the full component thickness; the Elbow occupies the narrower Hill-and-Valley interface width.

Full I-Wood corner assembly reinforced by a Knee — Complete Knee-reinforced corner

Close view of a full-thickness I-Wood Knee seated between two components — Full-thickness interface detail

End view showing an I-Wood Knee matching the full thickness of the component — Knee end view · thickness equals the component thickness

Knee · full-depth reinforcement

Component-width thickness for maximum bearing area.

The Knee is the thicker reinforcement. Its thickness matches the nominal thickness of the component, creating a broad connection through the full depth of the adjoining members. This larger bearing area makes the Knee appropriate where the corner requires the strongest and most substantial form of bracing.

Thickness: Equal to the component thickness.
Interface: Complementary routed faces engage the profiles on both components.
Function: Full-depth corner bracing with high resistance to racking and separation.

Full I-Wood corner assembly reinforced by an Elbow — Complete Elbow-reinforced corner

Close view of a reduced-thickness I-Wood Elbow seated between two components — Reduced-thickness interface detail

End view showing an I-Wood Elbow matching the width of the Hill-and-Valley interface — Elbow end view · thickness equals the Hill-and-Valley width

Elbow · reduced-depth reinforcement

Valley-width thickness in a lighter reinforcing plane.

The Elbow follows the same triangular bracing principle in a thinner form. Its thickness equals the width of the Hill or Valley interface, allowing it to register within the profiled zone while using less material and occupying less visual and physical depth than a Knee.

Thickness: Equal to the Hill or Valley width.
Interface: The slim reinforcing plane remains positively located by complementary geometry.
Function: Compact corner bracing where a full-depth Knee is not required.

Complementary by design

Hill meets Valley—in either orientation.

If the component presents a Valley, the Knee or Elbow receives a corresponding Hill on its mating face. If the component presents a Hill, the reinforcement is routed with the matching Valley. Reversing the profiles does not change the principle: one surface locates within the other, producing the same self-aligning, interlocking connection.

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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 VH members forming a hollow square column — 04 VH membersSquare hollow VH sectionA compact four-sided arrangement using the complementary VH profile 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.

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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
Jig-assisted square, hexagonal, and octagonal corner geometry
Knee and Elbow corner-reinforcement principles
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

EngineeringStandards