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The DFM design loop closes its own findings

Eight prompts, two per process — machining, injection moulding, sheet metal, additive — whose first build breaks a named design-for-manufacture rule on purpose: a thin wall, no draft, an unrelieved internal corner, an undersized pin. The loop runs cad_dfm_check, takes the remedy its finding names — a face to push out, edges to fillet, walls to draft — and sends it straight back to the kernel. No fillet radius or draft angle on this page was chosen by a person or by the loop: every number below is what the kernel measured before and after its own fix, and every picture is the kernel's own render or section of the body it measured.

8/8pass in ≤ 3 iterations

4processes, 2 prompts each

12fixes applied, all from the checker

0refusals hit while redesigning

Machine a 60 x 40 x 10 mm aluminium tray with a pocket leaving a 0.5 mm floor. — the part that passed, rendered by the kernel

Additive (Bambu X1 Carbon)

The eight parts as the loop left them, each one passing its process's rule pack. Pick one to see how it got there.

Machining (CNC mill)

Machine a 60 x 40 x 10 mm aluminium tray with a pocket leaving a 0.5 mm floor.

PASS · 3 iterations

Thin wall and unrelieved internal corner — the pocket floor is under the machining pack's hard wall floor, and its square corners are sharper than any 6 mm end mill can cut. The second rule was not deliberately dialled in — a square pocket cut with no corner relief always leaves sharp internal corners — but it is real and the loop closes it exactly like the one it was written for.

Rule(s) under test: min_wall_thickness, min_internal_corner_radius

iter	op applied	rule — measured vs limit	gate
0	(first build)	min wall thickness: 0.5 mm vs 0.8 mm FAIL min internal corner radius: 0 mm vs 3.6 mm FAIL	2 blocking
1	`cad_move_face`	min wall thickness: 0.8 mm vs 0.8 mm PASS min internal corner radius: 0 mm vs 3.6 mm FAIL	1 blocking
2	`cad_fillet_edges`	min wall thickness: 0.8 mm vs 0.8 mm PASS min internal corner radius: 3.6 mm vs 3.6 mm PASS	approved

Machine a 60 x 40 x 10 mm aluminium tray with a pocket leaving a 0.5 mm floor. — first build, rendered by the kernel — 0. first build

Machine a 60 x 40 x 10 mm aluminium tray with a pocket leaving a 0.5 mm floor. — after cad_move_face, rendered by the kernel — 1. after `cad_move_face`

Machine a 60 x 40 x 10 mm aluminium tray with a pocket leaving a 0.5 mm floor. — after cad_fillet_edges, rendered by the kernel — 2. after `cad_fillet_edges` passes

min wall thickness 0.5 → 0.8 mm (limit 0.8 mm) · min internal corner radius 0 → 3.6 mm (limit 3.6 mm)

Side section at y = 20 mm. Dashed: the first build. Filled: the part that passed. Right: the boxed region, enlarged ×4, where the outline moved most (1.14 mm).

Plan section at z = 9 mm. Dashed: the first build. Filled: the part that passed. Right: the boxed region, enlarged ×4, where the outline moved most (1.491 mm).

Mill a 60 x 40 x 20 mm block with a square-cornered 30 x 20 x 12 mm pocket — no corner relief for the cutter.

PASS · 2 iterations

Unrelieved internal corner — the pocket's square corners are sharper than any 6 mm end mill can cut.

Rule(s) under test: min_internal_corner_radius

iter	op applied	rule — measured vs limit	gate
0	(first build)	min internal corner radius: 0 mm vs 3.6 mm FAIL	1 blocking
1	`cad_fillet_edges`	min internal corner radius: 3.6 mm vs 3.6 mm PASS	approved

Mill a 60 x 40 x 20 mm block with a square-cornered 30 x 20 x 12 mm pocket — no corner relief for the cutter. — first build, rendered by the kernel — 0. first build

Mill a 60 x 40 x 20 mm block with a square-cornered 30 x 20 x 12 mm pocket — no corner relief for the cutter. — after cad_fillet_edges, rendered by the kernel — 1. after `cad_fillet_edges` passes

min internal corner radius 0 → 3.6 mm (limit 3.6 mm)

Side section at y = 20 mm. Dashed: the first build. Filled: the part that passed. Right: the boxed region, enlarged ×3, where the outline moved most (1.495 mm).

Plan section at z = 19 mm. Dashed: the first build. Filled: the part that passed. Right: the boxed region, enlarged ×4, where the outline moved most (1.491 mm).

Injection moulding

Injection-mould a 60 x 40 x 0.8 mm plate, vertical walls, no draft.

PASS · 3 iterations

Thin wall and no draft — the 0.8 mm plate is under the 1 mm wall floor and dead vertical against the pull.

Rule(s) under test: min_wall_thickness, min_draft_angle

iter	op applied	rule — measured vs limit	gate
0	(first build)	min wall thickness: 0.8 mm vs 1 mm FAIL min draft angle: 0 deg vs 1 deg FAIL	2 blocking
1	`cad_move_face`	min wall thickness: 1 mm vs 1 mm PASS min draft angle: 0 deg vs 1 deg FAIL	1 blocking
2	`cad_draft`	min wall thickness: 1 mm vs 1 mm PASS min draft angle: 1 deg vs 1 deg PASS	approved

Injection-mould a 60 x 40 x 0.8 mm plate, vertical walls, no draft. — first build, rendered by the kernel — 0. first build

Injection-mould a 60 x 40 x 0.8 mm plate, vertical walls, no draft. — after cad_move_face, rendered by the kernel — 1. after `cad_move_face`

Injection-mould a 60 x 40 x 0.8 mm plate, vertical walls, no draft. — after cad_draft, rendered by the kernel — 2. after `cad_draft` passes

min wall thickness 0.8 → 1 mm (limit 1 mm) · min draft angle 0 → 1 deg (limit 1 deg)

Side section at y = 20 mm. Dashed: the first build. Filled: the part that passed. Right: the boxed region, enlarged ×16, where the outline moved most (0.2 mm).

Injection-mould a 40 x 40 x 8 mm plate with a shallow square 10 x 10 x 3 mm pocket, no draft, no corner relief.

PASS · 3 iterations

No draft and unrelieved internal corner — every wall is dead vertical and the pocket's corners are sharp.

Rule(s) under test: min_internal_corner_radius, min_draft_angle

iter	op applied	rule — measured vs limit	gate
0	(first build)	min internal corner radius: 0 mm vs 0.5 mm FAIL min draft angle: 0 deg vs 1 deg FAIL	1 blocking
1	`cad_fillet_edges`	min internal corner radius: 0.5 mm vs 0.5 mm PASS min draft angle: 0 deg vs 1 deg FAIL	1 blocking
2	`cad_draft`	min internal corner radius: 0.5 mm vs 0.5 mm PASS min draft angle: 1 deg vs 1 deg PASS	approved

Injection-mould a 40 x 40 x 8 mm plate with a shallow square 10 x 10 x 3 mm pocket, no draft, no corner relief. — first build, rendered by the kernel — 0. first build

Injection-mould a 40 x 40 x 8 mm plate with a shallow square 10 x 10 x 3 mm pocket, no draft, no corner relief. — after cad_fillet_edges, rendered by the kernel — 1. after `cad_fillet_edges`

Injection-mould a 40 x 40 x 8 mm plate with a shallow square 10 x 10 x 3 mm pocket, no draft, no corner relief. — after cad_draft, rendered by the kernel — 2. after `cad_draft` passes

min internal corner radius 0 → 0.5 mm (limit 0.5 mm) · min draft angle 0 → 1 deg (limit 1 deg)

Side section at y = 20 mm. Dashed: the first build. Filled: the part that passed. Right: the boxed region, enlarged ×11, where the outline moved most (0.264 mm).

Plan section at z = 7 mm. Dashed: the first build. Filled: the part that passed. Right: the boxed region, enlarged ×18, where the outline moved most (0.1728 mm).

Sheet metal

Laser-cut and form a 40 x 30 x 10 mm sheet-metal tray with a pocket leaving a 0.3 mm floor.

PASS · 2 iterations

Thin wall — under the sheet-metal pack's sanity floor on the sheet itself.

Rule(s) under test: min_wall_thickness

Also trips min_internal_corner_radius (not under test): severity warning on the sheet_metal pack: the pocket has no corner relief; it fails the rule, not the gate, so the loop closes on the named rule alone

iter	op applied	rule — measured vs limit	gate
0	(first build)	min wall thickness: 0.3 mm vs 0.5 mm FAIL	approved
1	`cad_move_face`	min wall thickness: 0.5 mm vs 0.5 mm PASS	approved

Laser-cut and form a 40 x 30 x 10 mm sheet-metal tray with a pocket leaving a 0.3 mm floor. — first build, rendered by the kernel — 0. first build

Laser-cut and form a 40 x 30 x 10 mm sheet-metal tray with a pocket leaving a 0.3 mm floor. — after cad_move_face, rendered by the kernel — 1. after `cad_move_face` passes

min wall thickness 0.3 → 0.5 mm (limit 0.5 mm)

Side section at y = 15 mm. Dashed: the first build. Filled: the part that passed. Right: the boxed region, enlarged ×11, where the outline moved most (0.2 mm).

Laser-cut a 40 x 30 x 10 mm sheet-metal block with a square 20 x 15 x 5 mm pocket — no corner relief for the cutting head.

PASS · 2 iterations

Unrelieved internal corner — the pocket's square corners are sharper than the sheet-metal pack's cut-corner floor.

Rule(s) under test: min_internal_corner_radius

iter	op applied	rule — measured vs limit	gate
0	(first build)	min internal corner radius: 0 mm vs 0.75 mm FAIL	approved
1	`cad_fillet_edges`	min internal corner radius: 0.75 mm vs 0.75 mm PASS	approved

Laser-cut a 40 x 30 x 10 mm sheet-metal block with a square 20 x 15 x 5 mm pocket — no corner relief for the cutting head. — first build, rendered by the kernel — 0. first build

Laser-cut a 40 x 30 x 10 mm sheet-metal block with a square 20 x 15 x 5 mm pocket — no corner relief for the cutting head. — after cad_fillet_edges, rendered by the kernel — 1. after `cad_fillet_edges` passes

min internal corner radius 0 → 0.75 mm (limit 0.75 mm)

Side section at y = 15 mm. Dashed: the first build. Filled: the part that passed. Right: the boxed region, enlarged ×6, where the outline moved most (0.4945 mm).

Plan section at z = 9 mm. Dashed: the first build. Filled: the part that passed. Right: the boxed region, enlarged ×13, where the outline moved most (0.3107 mm).

Additive (FDM)

3D-print a 30 x 20 x 8 mm FDM tray with a pocket leaving a 0.4 mm floor.

PASS · 2 iterations

Thin wall — under two perimeters of the FDM pack's extrusion width, so it prints as a gap.

Rule(s) under test: min_wall_thickness

iter	op applied	rule — measured vs limit	gate
0	(first build)	min wall thickness: 0.4 mm vs 0.8 mm FAIL	1 blocking
1	`cad_move_face`	min wall thickness: 0.8 mm vs 0.8 mm PASS	approved

3D-print a 30 x 20 x 8 mm FDM tray with a pocket leaving a 0.4 mm floor. — first build, rendered by the kernel — 0. first build

3D-print a 30 x 20 x 8 mm FDM tray with a pocket leaving a 0.4 mm floor. — after cad_move_face, rendered by the kernel — 1. after `cad_move_face` passes

min wall thickness 0.4 → 0.8 mm (limit 0.8 mm)

Side section at y = 10 mm. Dashed: the first build. Filled: the part that passed. Right: the boxed region, enlarged ×6, where the outline moved most (0.4 mm).

3D-print (Bambu X1 Carbon, 0.4 mm nozzle, PLA) an L bracket with a 0.6 mm rib and a 1.0 mm free-standing pin.

PASS · 3 iterations

Thin wall and undersized pin — the rib is under the X1 Carbon pack's two-perimeter wall floor and the pin is under its printable-diameter floor.

Rule(s) under test: min_wall_thickness, x1c_min_pin_diameter

iter	op applied	rule — measured vs limit	gate
0	(first build)	min wall thickness: 0.6 mm vs 0.84 mm FAIL min pin diameter (X1C): 1 mm vs 1.5 mm FAIL	2 blocking
1	`cad_move_face`	min wall thickness: 0.84 mm vs 0.84 mm PASS min pin diameter (X1C): 1 mm vs 1.5 mm FAIL	1 blocking
2	`cad_move_face`	min wall thickness: 0.84 mm vs 0.84 mm PASS min pin diameter (X1C): 1.5 mm vs 1.5 mm PASS	approved

3D-print (Bambu X1 Carbon, 0.4 mm nozzle, PLA) an L bracket with a 0.6 mm rib and a 1.0 mm free-standing pin. — first build, rendered by the kernel — 0. first build

3D-print (Bambu X1 Carbon, 0.4 mm nozzle, PLA) an L bracket with a 0.6 mm rib and a 1.0 mm free-standing pin. — after cad_move_face, rendered by the kernel — 1. after `cad_move_face`

min wall thickness 0.6 → 0.84 mm (limit 0.84 mm) · min pin diameter (X1C) 1 → 1.5 mm (limit 1.5 mm)

Plan section at z = 12 mm. Dashed: the first build. Filled: the part that passed. Right: the boxed region, enlarged ×18, where the outline moved most (0.25 mm).

All 8, at a glance

process	prompt	rule(s)	iterations to pass	result
Machining (CNC mill)	Machine a 60 x 40 x 10 mm aluminium tray with a pocket leaving a 0.5 mm floor.	min wall thickness, min internal corner radius	3	pass
Machining (CNC mill)	Mill a 60 x 40 x 20 mm block with a square-cornered 30 x 20 x 12 mm pocket — no corner relief for the cutter.	min internal corner radius	2	pass
Injection moulding	Injection-mould a 60 x 40 x 0.8 mm plate, vertical walls, no draft.	min wall thickness, min draft angle	3	pass
Injection moulding	Injection-mould a 40 x 40 x 8 mm plate with a shallow square 10 x 10 x 3 mm pocket, no draft, no corner relief.	min internal corner radius, min draft angle	3	pass
Sheet metal	Laser-cut and form a 40 x 30 x 10 mm sheet-metal tray with a pocket leaving a 0.3 mm floor.	min wall thickness	2	pass
Sheet metal	Laser-cut a 40 x 30 x 10 mm sheet-metal block with a square 20 x 15 x 5 mm pocket — no corner relief for the cutting head.	min internal corner radius	2	pass
Additive (FDM)	3D-print a 30 x 20 x 8 mm FDM tray with a pocket leaving a 0.4 mm floor.	min wall thickness	2	pass
Additive (Bambu X1 Carbon)	3D-print (Bambu X1 Carbon, 0.4 mm nozzle, PLA) an L bracket with a 0.6 mm rib and a 1.0 mm free-standing pin.	min wall thickness, min pin diameter (X1C)	3	pass

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The DFM design loop closes its own findings

Machining (CNC mill)

Machine a 60 x 40 x 10 mm aluminium tray with a pocket leaving a 0.5 mm floor.

Mill a 60 x 40 x 20 mm block with a square-cornered 30 x 20 x 12 mm pocket — no corner relief for the cutter.

Injection moulding

Injection-mould a 60 x 40 x 0.8 mm plate, vertical walls, no draft.

Injection-mould a 40 x 40 x 8 mm plate with a shallow square 10 x 10 x 3 mm pocket, no draft, no corner relief.

Sheet metal

Laser-cut and form a 40 x 30 x 10 mm sheet-metal tray with a pocket leaving a 0.3 mm floor.

Laser-cut a 40 x 30 x 10 mm sheet-metal block with a square 20 x 15 x 5 mm pocket — no corner relief for the cutting head.

Additive (FDM)

3D-print a 30 x 20 x 8 mm FDM tray with a pocket leaving a 0.4 mm floor.

3D-print (Bambu X1 Carbon, 0.4 mm nozzle, PLA) an L bracket with a 0.6 mm rib and a 1.0 mm free-standing pin.

All 8, at a glance

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