Knock-down hardware

Hardware other than bed bolts for pieces that come apart — plus the two entries that are not knock-down at all but live in the same file: the glued dowel and the shelf pin.

These are what let a design satisfy requirements.knock_down without glue.

Threaded inserts

The one to reach for in sheet goods. A wood screw into the edge of MDF or plywood holds badly — every sheet material in the catalogue rates low or poor there. An insert converts a poor screw joint into a good machine-screw joint.

Id	Insert	Machine screw	Drive
fixtures.threaded_insert.m6	10 Ø × 13, M6	M6 × 40	Hex 4
fixtures.threaded_insert.m8	13 Ø × 15, M8	M8 × 50	Hex 5

Through part | Receiving part

Id	Clearance	Counterbore	Insert bore
m6	6.5, through	11 × 6	8.5 × 15 deep
m8	8.5, through	14 × 8	11 × 17 deep

Id	Min edge	Min end	Min engagement	Min spacing
m6	15	20	13	32
m8	20	26	15	40

End grain is allow — like a bed bolt, the load goes into steel rather than into wood.

The insert goes in before assembly and stays in. Only the machine screw comes out when the piece is taken apart, which is what makes this joint survive being assembled and disassembled repeatedly where a wood screw into the same hole would not.

Cam locks

Flat-pack hardware: a cam buried in one panel, a dowel bolt threaded into the other, and a quarter turn pulls them together.

Id	Cam	Bolt	Drive
fixtures.cam_lock.15	15 Ø × 12.5	7 Ø × 34	Pozi 2

Through part	Receiving part
15 mm bore, 12.5 deep · 8 mm cross bore at 9.5 depth, 24 long	5 mm bore, 12 deep

Min edge	Min end	Min engagement	Min spacing	Min panel thickness
12	24	11	64	15

Needs at least 15 mm of panel to bury the cam, which is why it does not belong in 12 mm ply. That minimum is enforced, and the finding names it.

End grain is warn: the dowel bolt threads into wood, so it is a real concern here in a way it is not for an insert.

Dowels

Id
fixtures.dowel.8x40	8 × 40 fluted beech	Both holes 8 Ø × 21 deep

Min edge	Min end	Min engagement	Min spacing
16	24	19	32

Both holes are 1 mm deeper than half the dowel so glue has somewhere to go and the joint actually closes. Two 20 mm holes for a 40 mm dowel is how you end up with a joint that will not seat.

A doweled joint is glued, so it is not knock-down. If the design declares requirements.knock_down: true and a dowel sits on the disassembly path, that is a finding. Dowels are here for alignment and for glued joinery, not for a piece that comes apart.

Shelf pins

Id
fixtures.shelf_pin.5	5 mm pin, 16 long	5 Ø × 10 deep, receiving part only

Min edge	Min end	Min engagement	Min spacing
10	20	9	32

Adjustable shelving is drilled on the 32 mm system, so a spacing that is a multiple of 32 keeps the whole drilling plan on one jig setting. Write it that way:

pattern: { along: length, count: 12, spacing: 32, from: 200 }

End grain is warn. The pin carries the shelf in shear, so the hole wants face grain around it.

Which to use

Situation	Reach for
Rail into the end of a post, must come apart	Bed bolt
Panel edge in sheet goods, must come apart	Threaded insert
Flat-pack carcass, 15 mm panels or thicker	Cam lock
Alignment in a glued joint	Dowel
Adjustable shelf	Shelf pin
Everything else, glued or not structural	Wood screw

Procurement

Id	Pack sizes	Unit cost
threaded_insert.m6	10 · 25 · 50	0.55
threaded_insert.m8	10 · 25	0.75
cam_lock.15	10 · 20	0.35
dowel.8x40	50 · 100	0.06
shelf_pin.5	20 · 100	0.09