Blade Retention Methods - Blade Generation System

Overview

Blade retention covers two distinct areas:

Blade-to-Blade - How blades interlock with each other at intersections
Blade-to-Baseplate - How blades mount into the fixture baseplate

Document Sections

Section	Topic
Blade-to-Blade Interlocking	N-blade / U-blade slot systems, clearances, crossover positioning
Blade-to-Baseplate Mounting	Tab/slot systems, locking mechanisms, captured nut mounting
JSON Configuration	Complete schema for all retention options

⚠️ Not to be confused with Part Retention

Blade Retention = How blades connect to each other and baseplate (this page)

Part Retention = How the workpiece is held by blades (see Part Retention)

🔗 Blade-to-Blade Interlocking

When two blades intersect (typically at 90°), one blade has a U-slot (receiver) and the other has an N-tab (insert). This section covers the geometry and clearance requirements.

Key Terms

Term	Description
U-Blade	Receiver blade with slot cut into it
N-Blade	Insert blade with tab/tongue that engages the slot
Crossover Height	Vertical position where blades intersect
Crossover Gap	Clearance or radius between intersecting faces

Slot Clearance Configuration

Clearance Dimensions

U-BLADE SLOT CLEARANCES (Top View) ══════════════════════════════════════════════════ ┌─── clearanceLeft │ ▼ ┌───────────────────────────┐ │ │ │ │ │ │ N-tab │ │ │ │ │ │ │ │ │◀──────────┼─── clearanceRight │ │ │ │ └───────────────────────────┘ │ │ │◀─────▶│ slot width additionalClearance = extra on BOTH sides

Parameter	Description	Default
`clearanceLeft`	Gap on left side of N-tab	0.1 mm
`clearanceRight`	Gap on right side of N-tab	0.1 mm
`additionalClearance`	Extra clearance added to both sides	0 mm

Total slot width = N-tab thickness + clearanceLeft + clearanceRight + (2 × additionalClearance)

Crossover Gap / Radius

Where the upper N-blade face crosses the lower U-blade face, you can specify either a gap (clearance) or a radius to ensure they don't touch:

CROSSOVER DETAIL (Side View at Intersection) ════════════════════════════════════════════════════ OPTION A: Gap (flat clearance) N-blade ────────┐ │ ┌──────┴──────┐ │ GAP ↕ │ ◀── crossoverGap (e.g., 2mm) ─────────┴─────────────┴───────── U-blade OPTION B: Radius (curved clearance) N-blade ────────┐ │ ╭───┴───╮ ╱ ╲ ◀── crossoverRadius (e.g., 3mm) ──────────╯ ╰────────── U-blade

Parameter	Description	Use Case
`crossoverGap`	Flat vertical gap between blade faces	Simple clearance, easy to machine
`crossoverRadius`	Radiused transition between faces	Stress relief, smoother load transfer

If both are specified, crossoverRadius takes precedence.

Crossover Height Positioning

Height Options

The crossover point (where U-slot is positioned) can be specified as:

CROSSOVER HEIGHT OPTIONS ════════════════════════════════════════════════════ ┌─────────────────────────┐ ◀── Blade top (100%) │ │ │ │ │ ═════════ │ ◀── Crossover at 50% (ratio mode) │ │ OR fixed at 25mm (fixed mode) │ │ │ │ └─────────────────────────┘ ◀── Blade bottom (0%) Total height at intersection = H RATIO MODE: crossoverHeight = H × ratio FIXED MODE: crossoverHeight = fixedValue (always)

Mode	Parameter	Description
Ratio	`crossoverRatio: 0.5`	50% of intersection height (scales with blade)
Fixed	`crossoverFixed: 25`	Always 25mm from bottom (constant)

When to Use Each Mode

Mode	Best For	Example
Ratio	Variable height blades, consistent proportions	Crossover always at center regardless of blade height
Fixed	Consistent baseplate clearance, robot access	All crossovers at 30mm for robot gripper clearance

⚠️ Height Validation

If crossoverFixed exceeds the actual blade intersection height, the system will:

Warn the user
Fall back to ratio mode (50%)

Keyhole Slot Variations

Slot Pattern Reference

Six keyhole slot variations showing different configurations for blade interlocking.

Retention Types

Type	Description	Serviceability
`keyhole`	Wide entry hole + narrow slot lock	Tool-free assembly
`friction-slot`	Simple slot, interference fit	Moderate - pry out
`cross-pin`	Both blades slotted, pin locks	Excellent - remove pin
`weld-only`	No mechanical interlock	Permanent
`none`	No retention (bridge blades)	N/A

🔩 Blade-to-Baseplate Mounting

Blades must be securely mounted to the fixture baseplate. Multiple methods are available depending on serviceability requirements and load conditions.

Mounting Method Overview

Method	Description	Serviceability	Strength
Tab + Slot	Blade tabs fit into baseplate slots	Excellent	Medium
Tab + Slot + Shift-Lock	Tabs shift sideways to lock	Good (with clip)	High
Captured Nut + Screw	Screw from below into blade foot	Excellent	High
Direct Weld	Blade welded to baseplate	None (permanent)	Very High

Tab + Slot Mounting

Basic Tab/Slot System

Blade foot has tabs that drop into matching slots in the baseplate:

TAB + SLOT MOUNTING (Side View) ═══════════════════════════════════════════════════ BLADE ┌─────────────────┐ │ │ │ │ │ │ └──┬─────────┬────┘ │ TAB │ │ │ │ │ ◀── Tab depth options: │ │ - Through (full thickness) │ │ - Partial (fixed depth) │ │ - User-defined ═══╪═════════╪═══════════ BASEPLATE │ │ │ SLOT │ └─────────┘

Tab Depth Options

Option	Description	Use Case
`through`	Tab passes completely through baseplate	Maximum engagement, visual confirmation
`partial`	Tab stops at percentage of baseplate thickness	Clean underside, calculated depth
`fixed`	Tab depth is fixed value (e.g., 10mm)	Consistent depth regardless of baseplate

Slot Configuration

BASEPLATE SLOT (Top View) ═════════════════════════════════════════ ┌─────────────────────────────────────┐ │ │ │ ┌───────────────────────┐ │ │ │ │ │ │ │ SLOT │ │ ◀── slotLength │ │ │ │ │ └───────────────────────┘ │ │ │ │ │ ▼ │ │ slotWidth │ │ (blade thickness + clearance) │ │ │ └─────────────────────────────────────┘ BASEPLATE

Parameter	Description	Default
`slotWidth`	Blade thickness + clearance	auto + 0.2mm
`slotLength`	Length of slot in baseplate	blade length
`slotDepth`	Depth of slot (or "through")	through
`tabCount`	Number of tabs per blade	auto (based on length)
`tabSpacing`	Distance between tabs	100mm

Shift-Lock Tab System

🆕 Locking Mechanism

Tabs pass through baseplate, then blade shifts sideways to lock. A retaining clip prevents the blade from shifting back.

Shift-Lock Operation

SHIFT-LOCK MECHANISM (Top View - Looking Down) ══════════════════════════════════════════════════════════ STEP 1: Insert blade vertically BLADE │ ┌────────────┼────────────┐ │ │ │ │ ┌──────┴──────┐ │ │ │ SLOT │ │ BASEPLATE │ └─────────────┘ │ │ ↓ │ └─────────────────────────┘ STEP 2: Shift blade LEFT to lock BLADE │ ┌────────────┼────────────┐ │ ┌────┴────┐ │ │ │ TAB │ │ │ ◀────│ SHIFTED │ │ BASEPLATE │ │ │ │ │ └─────────┘ │ └─────────────────────────┘ Tab now underlaps baseplate edge STEP 3: Insert retaining clip ┌─────────────────────────┐ │ CLIP ┌─────────┐ │ │ ████ │ TAB │ │ │ ████───│ LOCKED │ │ BASEPLATE │ ████ │ │ │ │ └─────────┘ │ └─────────────────────────┘ Clip prevents shift-back

Lock Geometry

Parameter	Description	Default
`shiftDistance`	How far blade shifts to lock	5mm
`lockLip`	Undercut depth in baseplate	3mm
`clipSlot`	Slot for retaining clip	enabled
`clipType`	Sheet metal spring clip design	"nucleo"

Retaining Clip (Nucleo Style)

The same clip design used in Nucleo fixtures - sheet metal spring clip that snaps into a slot:

RETAINING CLIP PROFILE ══════════════════════════════════════════ ┌─────────────────────────┐ │ ○ ○ │ ◀── Snap tabs │ \ / │ │ \ / │ │ \_______█_______/ │ ◀── Blade contact │ │ │ └────────────┴────────────┘ ↓ Locks against blade Prevents shift-back

📦 Generated Files

baseplate_shift_slot.dxf - Slots with lock geometry

blade_lock_clip.dxf - Retaining clip profile (laser cut)

Captured Nut + Screw Mounting

🆕 Screw-Up Mounting

Similar concept to the plunger T-slot mount, but inverted. A captured nut in the blade foot allows a screw from below to secure the blade to the baseplate.

Assembly Cross-Section

CAPTURED NUT MOUNTING (Side View) ════════════════════════════════════════════════════════ BLADE ┌─────────────────────┐ │ │ │ │ │ │ └──────────┬──────────┘ │ ┌───────┴───────┐ │ ┌───────┐ │ ◀── Nut pocket in blade foot │ │ NUT │ │ │ └───┬───┘ │ │ │ │ ══════════╪═══════╪═══════╪══════════ BASEPLATE │ │ │ │ │ │ ◀── Clearance hole in baseplate └───────┼───────┘ │ ┌──┴──┐ │SCREW│ ◀── Screw from below │ ▼ │ └─────┘ Screw threads into captured nut, pulling blade tight to baseplate

Component Details

Component	Description
Nut Pocket	Recess in blade foot sized to capture nut
Captured Nut	Standard hex nut held in pocket (can't spin)
Baseplate Hole	Clearance hole for screw to pass through
Screw	Socket head or countersunk from below

Dimensional Parameters

Parameter	M5	M6	M8	Description
`nutWidth`	8mm	10mm	13mm	Nut across flats
`nutHeight`	4mm	5mm	6.5mm	Nut thickness
`pocketDepth`	5mm	6mm	8mm	Pocket in blade foot
`clearanceHole`	5.5mm	6.5mm	9mm	Baseplate hole diameter
`countersink`	optional	optional	optional	For flush screw heads

👍 Advantages

Positive clamping - Screw pulls blade down firmly
Fully serviceable - Remove screw, blade lifts out
Adjustable - Can tighten or loosen as needed
No welding - Completely mechanical

👎 Disadvantages

Access required - Need access to underside of baseplate
More components - Nut + screw per location
Thicker blade foot - Must accommodate nut pocket

🔄 Mounting Method Comparison

Criteria	Tab + Slot	Shift-Lock	Captured Nut	Weld
Serviceability	Excellent	Good	Excellent	None
Strength	Medium	High	High	Very High
Assembly Time	Fast	Medium	Medium	Slow
Component Count	0	1 (clip)	2 (nut, screw)	0
Underside Access	Optional	No	Required	No
Best For	Light duty, prototypes	Production fixtures	Heavy duty, serviceable	Permanent fixtures

💡 Selection Guide

Prototype / light loads → Tab + Slot
Production / medium loads / no underside access → Shift-Lock
Heavy loads / full serviceability → Captured Nut
Permanent / maximum strength → Weld

📡 JSON Configuration

Complete Blade Retention Schema

"bladeRetention": { // ═══════════════════════════════════════════════════════ // BLADE-TO-BLADE INTERLOCKING // ═══════════════════════════════════════════════════════ "bladeToBlade": { "type": "keyhole", // "keyhole" | "friction-slot" | "cross-pin" | "weld-only" | "none" // --- Slot Clearances --- "clearanceLeft": 0.1, // mm - gap on left side of N-tab "clearanceRight": 0.1, // mm - gap on right side of N-tab "additionalClearance": 0, // mm - extra on BOTH sides // --- Crossover Configuration --- "crossover": { "mode": "ratio", // "ratio" | "fixed" "ratio": 0.5, // 0.0-1.0 (if mode=ratio) "fixedHeight": 25, // mm (if mode=fixed) "gapOrRadius": "gap", // "gap" | "radius" "gap": 2, // mm clearance between faces "radius": 3 // mm fillet radius (if gapOrRadius=radius) }, // --- Keyhole Options --- "keyhole": { "enabled": true, "entryDiameter": "auto", // "auto" = slot width × 2 "position": "bottom" // "top" | "bottom" }, // --- Relief Holes --- "reliefHoles": { "enabled": true, "count": 2, "diameter": 4, // mm "offsetFromSlot": 8 // mm from slot centerline }, // --- Alignment Hole --- "alignmentHole": { "enabled": false, "type": "square", // "square" | "round" "size": 5 // mm } }, // ═══════════════════════════════════════════════════════ // BLADE-TO-BASEPLATE MOUNTING // ═══════════════════════════════════════════════════════ "bladeToBaseplate": { "type": "tabSlot", // "tabSlot" | "shiftLock" | "capturedNut" | "weld" // --- Tab Configuration --- "tab": { "count": "auto", // "auto" | number "spacing": 100, // mm between tabs "width": 20, // mm "depth": "through" // "through" | "partial" | number (mm) }, // --- Slot Configuration --- "slot": { "widthClearance": 0.2, // mm added to blade thickness "cornerRadius": 1 // mm (for CNC milling) }, // --- Shift-Lock Options (if type=shiftLock) --- "shiftLock": { "shiftDistance": 5, // mm blade shifts to lock "lockLip": 3, // mm undercut depth "clipType": "nucleo", // "nucleo" | "spring" | "custom" "generateClipDXF": true }, // --- Captured Nut Options (if type=capturedNut) --- "capturedNut": { "threadSize": "M6", // M5, M6, M8 "nutType": "hex", // "hex" | "square" "screwHead": "socket", // "socket" | "countersunk" | "button" "countersinkBaseplate": true, "nutSpacing": 150 // mm between nut locations } } }

Quick Examples

Use Case	Configuration
Serviceable prototype	`"bladeToBlade": {"type": "keyhole"}, "bladeToBaseplate": {"type": "tabSlot"}`
Production fixture	`"bladeToBlade": {"type": "friction-slot"}, "bladeToBaseplate": {"type": "shiftLock"}`
Heavy duty serviceable	`"bladeToBlade": {"type": "cross-pin"}, "bladeToBaseplate": {"type": "capturedNut"}`
Permanent maximum strength	`"bladeToBlade": {"type": "weld-only"}, "bladeToBaseplate": {"type": "weld"}`