Clamping Shelves — Blade-Mounted Accessories

Side Plates & Bend-Tab Clamps

See also: Articulating Features for compliant/spring mechanisms, Blade-Mounted Accessories for full category list.

Purpose

Two new edge feature types for mounting clamping devices to blade faces. These provide downward clamping force to hold parts during cutting. Both types use the face detection modes above to determine placement surfaces.

Feature Type Registry

Type ID	Name	Constant	Description
7	Side Plate (Gusset)	`i_EDGE_FEAT_SIDE_PLATE`	Clip-together flat pieces with triangular gusset braces
8	Bend-Tab T-Plate	`i_EDGE_FEAT_BEND_TAB`	Single-piece bent clamp shelf, self-locking, 3-bend design

11.1 Variant A: Side Plate with Gusset (Clip-Together)

Multiple flat laser-cut pieces that slot together and bolt to the blade face. Triangular gusset braces provide structural rigidity. Best for heavy clamping loads, thick materials, and permanent fixtures.

3-5 parts per station (plate + gussets + fasteners)
Any material thickness
What you model IS the DXF — no unfold calculation needed
Each piece independently replaceable

2019 Prototype — Side Plate Clamp Stations (SolidCut CAD)

2019 Side plate clamp prototype - top-down isometric view showing blade with gusset clamp stations

Top-down isometric: Blade with side plate clamp stations at both ends. Triangular gusset braces, flat shelves with bolt holes, vertical through-slots in blade walls.

2019 Side plate clamp prototype - front isometric view showing 4 tilted clamp stations along blade

Front isometric: Four tilted clamp stations along front face plus end gussets. Shelves mount flush to blade inside walls. Note compound S-curve profile transitions between heights.

Historical Context (2019 Development)

These screenshots from the original 2019 SolidCut development show the side plate concept with triangular gusset braces already modeled as 3D solid geometry. Key observations from this prototype:

Gusset braces are triangular plates slotted into the blade wall — self-locating via tab-and-slot
Flat shelves extend outward from the blade face with multiple bolt-hole patterns
Clamp stations placed at varying heights along the blade profile
End stations use larger gussets for additional rigidity at blade terminations
Compound blade profile (S-curve transitions) demonstrates real-world fixture geometry
Vertical through-slots in blade walls accept gusset tabs — cut during blade fabrication

This 2019 work forms the basis for Variant A in the current system. The new automation will generate these assemblies programmatically from face detection results, rather than manual placement.

11.2 Variant B: Bend-Tab T-Plate (3-Bend Self-Locking Clamp)

Key Innovation

A single flat laser-cut blank (double-T shape) that bends at three scored lines and enters the blade twice — through a top mortise and back through a lower ratchet slot — creating a self-locking clip secured with a pin.

Concept Drawing (Rev G)

Assembled ZX Profile (the “7” Shape) — ASCII Reference

      BACK            │BLADE│         FRONT
                      │     │
 stop ════════════════╪═════╪═╗
 (wide)               │ mor │ ║ BEND 1 (+10° shown, could be -10°)
                      │ tise│  ╲
                      │     │   ╲═══════════╗ ← shelf (~15mm span)
                      │     │               ║   clamp on top
                      │     │               ║
                      │     │               ║ BEND 2 (−135°)
                      │     │              ╱
                      │     │            ╱
                      │     │          ╱   leg
                      │     │        ╱
                      │     │      ╱
                      │     │    ╱
          pin ○───────╪─■■■─╪══╝ BEND 3 → tab thru this slot
                      │─────│
                      │─────│  ← more ratchet slots
                      │─────│    (pick higher = shelf higher)
                      │─────│    (pick lower = shelf lower)
                      │     │

Material Path Through Blade

Back stop sits against back face (wider than mortise, prevents pull-through)
Through top mortise — passes through blade
Exits front face — BEND 1 tilts shelf up or down (±10-15°)
Shelf extends ~15mm out from front face — clamp mounts here
BEND 2 at shelf tip — the big −135° kick, leg angles back toward blade
Leg runs back toward blade at ~45° from vertical
BEND 3 at leg bottom — tab goes horizontal, through chosen ratchet slot
Tab exits back side — secured with pin through hole in tab

Three Bends

Bend	Location	Angle	Purpose
1	Just past front blade face	±10-15°	Shelf tilt (up or down)
2	Shelf tip (end of ~15mm span)	−135°	Leg kick-back toward blade
3	Bottom of leg (near blade face)	Calculated	Tab horizontal through ratchet slot

Four Degrees of Adjustability

Control	How	Range
Shelf tilt	Bend 1 angle	±10-15° from horizontal
Shelf span	Fixed by blank geometry	Designed per application
Leg angle	Bend 2 (always ~−135°)	Fixed by score line position
Height on blade	Which ratchet slot tab enters	Discrete steps (e.g. 5mm)

Blade Modifications Required

Top mortise slot — horizontal through-slot for shelf to pass through
Ratchet slot column — multiple through-slots below mortise for height adjustment
Pin hole — for locking tab on back side

Bend-Tab Clamp — CAD Model

Bend-tab clamp isometric view showing shelf angled upward at approximately 45 degrees from blade surface

Isometric View: Bend-tab clamp inserted through blade. The shelf portion (white) angles upward at ~45° from the blade face to create the clamping surface. Pin hole visible at top for securing. Pink back stop plate sits behind blade, wider than the through-slot to prevent pull-through. The small radii at the blade intersection mark the bend line position.

Bend-tab clamp plan elevation showing clamp passing through blade with retaining wings and corner reliefs

Plan Elevation: Clamp passes through blade (grey). The inner slot and small corner radii at the blade face are where the bend occurs — material folds upward here to form the angled shelf. Pin hole at top center. Corner reliefs (semicircular cutouts) at the slot/blade intersections prevent stress concentration. Back stop plate visible below blade.

Note: The isometric view does not clearly show the bend angle — the shelf nominally angles upward at ~45° (or as specified by bendAngle1_tilt) to provide a horizontal or near-horizontal clamping surface for the workpiece. The bend occurs at the small radii / inner slot visible in the front elevation where the clamp exits the blade face.

Material Gauge Limits & Forming Method Selection

Variant Selection by Gauge

Gauge	Thickness	Forming	Recommended Variant
18-16ga	1.2-1.5mm	Hand bend	Bend-Tab (Variant B)
14ga	2.0mm	Hand bend (mild steel) / Press brake (stainless)	Bend-Tab (Variant B) — sweet spot
12ga	2.5mm	Press brake required	Bend-Tab (Variant B) with press brake, or Side Plate (Variant A)
10ga+	3.0mm+	Press brake / fabrication	Side Plate (Variant A) recommended

Rule of thumb: If press brake is required, consider whether Side Plate (Variant A) is more practical — no bending needed, just flat laser-cut pieces that bolt together.

Bend Relief Voids

Bend relief voids (notches at bend lines) prevent material tearing during forming. Required for all bend-tab clamps. Dimensions scale with material thickness:

Void width ≥ 2× material thickness (minimum clearance for bend tooling)
Void depth ≥ material thickness + 0.5mm (prevents stress concentration)
Rib connection width — solid material between voids — must be sufficient for structural strength

Recommended minimums:
  14ga (2.0mm): relief width 4mm, depth 2.5mm, rib width 8mm
  12ga (2.5mm): relief width 5mm, depth 3.0mm, rib width 10mm

Bend Allowance (Shared with Zigzag Blades)

BA = π × (R + K × T) × (θ / 180)

Where:
  R = inside bend radius (mm)
  K = K-factor (0.33 air bend, 0.50 bottoming)
  T = material thickness (mm)
  θ = bend angle (degrees)

Example: 14ga steel (2mm), R=1.5mm, K=0.4
  Bend 1 (10°):  BA = π × 2.1 × 0.056 = 0.37mm
  Bend 2 (135°): BA = π × 2.1 × 0.750 = 4.95mm
  Bend 3 (~45°): BA = π × 2.1 × 0.250 = 1.65mm

Ratchet Slot Reachability

Not every ratchet slot is reachable at every tilt angle. The combination of bend 1 angle, shelf span, leg length, and bend 2 angle determines which slot the tab can reach. The system must validate reachability and warn if the chosen slot is unreachable.

Z_tab = Z_mortise - shelfSpan × sin(tilt) - legLength × cos(kick_effective)
Valid slot = closest ratchet slot to Z_tab within ± (spacing / 2)

11.2.5 Variant C: Flex-Lug Clamp Shelf (Concept)

Status: Concept / Under Development

This variant extends the bend-tab design with integral spring-loaded contact lugs. The concept needs further discussion and validation before implementation.

Concept

Extends the standard bend-tab clamp shelf (Variant B) with vertical "flex lugs" that provide spring-loaded contact with the workpiece. The base uses the existing mortise/ratchet system for coarse positioning, while serpentine cuts in the lugs provide passive compliance.

Design Comparison: TruArc-Style vs Flex-Lug Approach

TruArc-Style (Complex)

Flex-Lug (Simple)

Estimated Design Time Comparison

Task	TruArc-Style	Flex-Lug (Parametric)	Savings
Initial CAD design	20-40 hrs	2-4 hrs (library setup)	~90%
Iteration / prototyping	10-20 hrs	1-2 hrs (parameter tweaks)	~90%
Per-job customization	4-8 hrs	0.5-1 hr (select type, place)	~85%
BOM / procurement	2-4 hrs (multiple parts)	0.25 hr (single blank)	~90%
Total per fixture	36-72 hrs	4-8 hrs	~85%

Key Insight

The TruArc-style mechanism is highly capable but requires:

Multiple sourced parts — turnbuckle, rod-end bearings, pins, fasteners
Assembly time — fitting, adjusting, threading
Custom CAD per job — adapting to part geometry

The Flex-Lug approach trades some adjustability for dramatic simplicity:

Single laser-cut blank — shelf + lugs + spring cuts in one piece
Zero assembly — bend and install
Parametric library — select from library, override as needed

For high-volume fixture shops, this could mean 10x faster turnaround on compliant clamping solutions.

Potential Advantages

Single bent blank (no separate actuator, rod-ends, turnbuckle)
Uses existing mortise/ratchet system for coarse height adjustment
Integral spring compliance via laser-cut serpentine pattern
Simpler manufacturing than TruArc-style mechanisms
Passive spring force (no manual tightening needed per cycle)

Open Questions

How much clamping force can be achieved with passive flex lugs vs actuated mechanisms?
Optimal lug geometry and spring cut patterns for various applications
Integration of 1 vs 2 flex lugs per shelf bracket
Whether the flex section should be in the lug or the shelf-to-lug connection

Preliminary JSON Structure

Concept Stage: The Flex-Lug variant (BT-FLEX-LUG-14) schema will be added to the JSON Schema Reference when the design is finalized. Key additions include flexLugs object with spring pattern, contact pad, and lug geometry parameters.

See also: Articulating Edge Features for related flex mechanisms including turnbuckle-actuated clamps.

11.3 Comparison Table

Aspect	Variant A (Gusset/Clip)	Variant B (Bend-Tab)	Variant C (Flex-Lug) *
Parts count	3-5 per station	1 (single blank)	1 (single blank)
Blade modifications	Multiple slots + additions	1 mortise + ratchet slots	1 mortise + ratchet slots
Tilt adjustment	Fixed at fabrication	Bend 1 angle (±10-15°)	Bend 1 angle (±10-15°)
Height adjustment	None	Ratchet slot selection	Ratchet + flex compliance
Compliance	None (rigid)	None (rigid)	Passive spring (serpentine cuts)
Removal	Difficult (bolted)	Pull pin, slide out	Pull pin, slide out
Strength	Higher (triangulated)	Moderate (bent sheet)	Lower (spring section)
Cost	Higher	Low	Low
Gauge range	Any thickness	16-12ga only	16-12ga only
Use case	Heavy loads, permanent	General clamping	Compliant contact, weld fixtures

* Variant C is a concept under development

11.4 JSON Configuration — Library-Based Schema

📋 Master Schema Reference

For the authoritative schema definitions, see the JSON Schema Reference:

Two-Level Architecture

Clamp/shelf types are defined once at the file level in a reusable library, then referenced by ID at the blade level with position and override information. This avoids duplication and ensures consistency across blades.

File-level library — defines parametric clamp types (dimensions, material, leg count, bend angles, holes, etc.)
Blade-level placements — references library types by ID, adds position along edge, face selection, and per-instance overrides

File-Level: Clamp Shelf Library

Defines parametric clamp types including bend-tab (BT-STD-14, BT-WIDE-12) and side-plate (SP-HEAVY-2G) variants.

See: JSON Schema Reference → Clamp Shelf Library

File-Level: Custom Profiles Library

Define custom cutout shapes for shelf mating plates. Profiles are defined once at file level, then referenced by ID in clamp type definitions. Supports PEPS kurve format (native), SVG path syntax, or parametric shapes.

See: JSON Schema Reference → Custom Profiles

Blade-Level: Clamp Placements

References library types by ID, adds position along edge, face selection, and per-instance overrides.

See: JSON Schema Reference → Blade-Level Placements

Custom Profile Formats

Format	Description	Example
`peps-kurve`	Native PEPS kurve syntax (lines: `tx y`, arcs CW: `tx y xc yc`, arcs CCW: `ax y xc yc`)	`"x0 y0 tx10 y0 tx10 y10 tx0 y10 tx0 y0"`
`svg-path`	SVG path d attribute syntax (M, L, A, Z commands)	`"M0,0 L10,0 L10,10 L0,10 Z"`
`parametric`	Predefined shapes with dimensions	See Parametric Shapes below

Parametric Shapes

Shape	Parameters	Description
`rectangle`	width, height, cornerRadius (opt)	Rectangle, optional rounded corners
`obround`	width, height	Slot with semicircle ends (pill shape)
`circle`	dia	Simple circle
`diamond`	width, height	Diamond/rhombus shape
`hexagon`	across_flats	Regular hexagon

Custom Profile Parameters Reference

Group	Parameter	Type	Description
(profile root)	description	string	Human-readable description
	origin	string	center, corner — reference point for placement
	format	string	peps-kurve, svg-path, or parametric
	data	string	Profile geometry (for peps-kurve and svg-path)
(parametric)	shape	string	rectangle, obround, circle, diamond, hexagon
	width / height / dia	float	Shape dimensions (mm)
	cornerRadius	float	Corner radius for rectangle (mm)
`shelfCutouts[]`	profileRef	string	Reference to customProfiles library ID
	count	int	Number of cutouts (default: 1)
	spacing / axis	float / string	Spacing between cutouts, axis direction (width or span)

Position Modes

Mode	Value	Description
`percent`	0–100	Percentage along edge (0 = start, 100 = end)
`absolute`	mm	Distance from edge start in millimeters
`fromEnd`	mm	Distance from edge end in millimeters

Clamp Type Parameters Reference

Group	Parameter	Type	Description
(root)	partNumber	string	Formal part number for inventory/drawings
(root)	description	string	Human-readable description of clamp type
`material`	gauge	int	Sheet metal gauge (10–20)
	thickness	float	Thickness in mm
	material	string	mild-steel, stainless, aluminum
`shelf`	span	float	Projection from blade face (mm)
	width	float	Width perpendicular to blade (mm)
	depth	float	Depth for sidePlate variant (mm)
`leg`	length	float	Leg length from shelf tip (mm)
`leg`	count	int	Number of legs (1 = center, 2 = split)
`bends`	kick	float	Bend 2 angle (degrees, −135 typical)
	kFactor	float	K-factor for BA calc (0.3–0.5)
	insideRadius	float	Inside bend radius (mm)
`bends.relief`	type	string	notch, radius, or none
	width	float	Void width at bend line (mm), typically ≥2× thickness
	depth	float	Void depth into material (mm), typically ≥ thickness
(root)	shape	string	semicircle, square, vee
(root)	formingMethod	string	hand, press-brake, roll
`ribConnection`	width	float	Solid material width between voids (mm)
`backStop`	overhang	float	Overhang beyond mortise width (mm), prevents pull-through
`ratchet`	slotCount	int	Number of height-adjust slots
`ratchet`	slotSpacing	float	Vertical spacing between slots (mm)
`holes.shelf`	pattern	string	linear, grid, radial, or custom
	count	int	Number of holes (linear pattern)
	rows / cols	int	Grid dimensions (grid pattern)
	dia	float	Hole diameter (mm)
	spacing	float	Distance between holes (linear, mm)
	spacingX / spacingY	float	Grid spacing in X and Y (mm)
	origin	string	center, corner, or edge
	axis	string	width or span (linear pattern direction)
	rotation	float	Rotate hole pattern about shelf center (degrees)
`holes.pin`	dia	float	Retaining pin hole diameter (mm)
`holes.pin`	fromTop	float	Distance from tab top edge (mm)
`countersink`	dia	float	Countersink diameter (mm)
`countersink`	depth	float	Countersink depth (mm)
`cornerBlends`	shelfEdges	float	Blend radius on shelf plate edges (mm)
	backStopEdges	float	Blend radius on back stop/retention flange (mm)
	lockingProngs	float	Blend radius on ratchet locking tabs (mm)
	legEdges	float	Blend radius on leg edges (mm)
`gussets`	count	int	Number of triangular braces
	angle	float	Gusset angle from vertical (degrees)
	height	float	Gusset height (mm)
`fasteners`	type	string	bolt, rivet, weld-stud
	dia	float	Fastener diameter (mm)
	count	int	Fasteners per station

Blade-Level Override Parameters

Parameter	Type	Description
`ref`	string	Required. Library type ID to use
`face`	string	Required. left-inside, left-outside, right-inside, right-outside, front, back
`position`	object	Required. { mode, value } — see Position Modes above
`ratchetSlotIndex`	int	Which ratchet slot (0 = lowest). bendTab only.
`tiltOverride`	float	Override bend 1 tilt angle (±15°)
`mirror`	bool	Mirror clamp geometry (default: false)
`enabled`	bool	Enable/disable this placement (default: true)
`overrides`	relief.width	float	Override relief void width (mm)
	relief.depth	float	Override relief void depth (mm)
	ribConnection.width	float	Override rib connection width (mm)

11.5 Macro Architecture

Shared Parallel-Bend Engine

Both Variant B (bend-tab clamps) and zigzag blades use the same fxParallelBend engine. The geometry is always N rectangular segments joined at N-1 parallel bend lines, all perpendicular to the base. The 3D solid is built by extruding each rectangle (SLD BLO), rotating to the bend angle, and unioning all pieces. The flat pattern is the same rectangles laid inline with BA deductions at each joint, stored as a named figure/kurve associated with the solid body.

fxParallelBend.ovm               ← SHARED ENGINE (clamps + zigzag blades)
  ├── fxPB_Build3D                 N segments → BLO + rotate + UNI → solid
  ├── fxPB_BuildFlat               BA-deducted flat pattern → figure/kurve
  └── fxPB_ExportDXF               Layers: outline, scores, holes

fxEdgeFeat_Dispatch              ← Main edge feature dispatcher
  ├── type 1-6                   ← Existing features (grippers, plungers, etc.)
  ├── type 7 → fxSidePlate       ← Variant A (clip-together gusset)
  │   ├── fxSP_BuildLocalCS
  │   ├── fxSP_PlateProfile
  │   ├── fxSP_GussetProfile
  │   ├── fxSP_Slots + Fasteners
  │   └── fxSP_Transform + Boolean
  └── type 8 → fxBendTab         ← Variant B (3-bend T-plate)
      ├── fxBT_PrepSegments        4 segments, 3 angles → arrays
      ├── call fxPB_Build3D        → i_clampBody (3D solid)
      ├── call fxPB_BuildFlat      → k(n) flat pattern figure
      ├── fxBT_AddShelfHoles       Drill into 3D + mark on flat
      ├── fxBT_BuildMortiseSlot    (subtract from blade)
      ├── fxBT_BuildRatchetSlots   (column of height-adjust slots)
      └── fxBT_TransformToWorld

fxZigzagBlade.ovm (future)       ← Same shared engine, different inputs
  ├── fxZZ_PrepSegments            N segments, N-1 angles → arrays
  ├── call fxPB_Build3D            → i_zigzagBody (3D solid)
  └── call fxPB_BuildFlat          → k(n) flat pattern figure