Blog · 2026-10-19 · Andrii Shylenko

Bolted joints from one fastener table

The model above is a flange with eight M6 bolts. Drag it to turn it. Every screw, washer and nut in this post comes from one table of ISO metric fasteners, and the table picks the sizes each joint needs.

The live model. Drag to turn it.

One table, not a pile of models

kernelCAD knows socket-head, button-head, countersunk and hex-head screws, set screws, threaded rod, hex nuts, lock nuts and washers. Sizes run from M2 to M20 where the standard has a size, and the lengths are the lengths suppliers stock. If you ask for an M2 × 50 that does not exist, it says so and lists the sizes that do.

One part from each family on a display base — Hex bolt, socket head, countersunk, button head and set screw standing; hex nut, lock nut and washers lying flat; an M8 × 250 rod in front.

Close-up of the head forms — M10 socket head (ISO 4762), hex head bolt (ISO 4017), countersunk (ISO 10642), button head (ISO 7380) and set screw (ISO 4026); ISO 4032 nut, DIN 127 B spring washer and ISO 7089 washer. The countersunk head shows its flat face; its 90° cone is underneath.

A lap joint

Two 6 mm bars overlap by 24 mm. One M5 bolt holds them. You give the grip (12 mm) and the mode (bolt), and the table returns the screw length plus the members.

The stack is 12 mm of bars, a 1 mm washer, a 4.7 mm nut and two thread pitches past the nut: 20.3 mm. The next stocked length is M5 × 25, which leaves 6.3 mm of thread showing. If no stocked length can reach the grip, the call fails and tells you the length it needed.

The lap joint with the M5 bolt stack — Two 6 mm bars, one bolt-mode stack. The seat is the upper bar's top face.

Front elevation of the stack — Head washer on the seat, tail washer and hex nut under the lower bar; the M5 × 25 ends 6.3 mm past the nut.

Holes you already drew

The other direction starts from the part. The plate has four Ø5.5 holes and two Ø3.4 holes. Ø5.5 is the normal clearance for M5, so the four holes take M5 screws. Ø3.4 is the normal clearance for M3, so the two holes take M3 screws. kernelCAD covers every hole with the same diameter and axis, so a pattern costs no extra work.

For a flat-head screw it cuts the 90° countersink the head needs. For a socket-head screw it leaves the hole as drawn. The washers and nuts land on the back.

Four flat-head bolts and two socket-head screws placed from the holes — The plate after the call: six stacks placed. The flat-head screws sit flush, so from above you see only the head face and its hex socket.

A flange ring

The ring has eight Ø6.6 holes on an 85 mm bolt circle and is 10 mm thick. Ø6.6 is the normal clearance for M6. With a 1.6 mm washer and a 5.2 mm nut, the stack needs 18.8 mm, so each hole gets an M6 × 20 bolt. One call covers all eight.

Bolted flange ring — Eight M6 flat-head bolts on an 85 mm bolt circle. The heads sit flush in the cut countersinks.

Under the flange ring — Under the ring: tail washer, ISO 4032 nut and 3.2 mm of chamfered screw tip on each of the eight stacks.

Fits

ISO 273 gives three clearance classes. For M6 they are 6.4 mm close, 6.6 mm normal and 7.0 mm loose. The table matches the hole to the thread and reports the class, so a plate drilled for a loose fit still gets the right screw. The match tolerance is 0.1 mm, which keeps a 5 mm tap drill from reading as an oversized M4 hole.

Limits

All sizes are nominal table values. The threads are drawn at the ISO coarse pitch, but they are not certified hardware. The spring washer is drawn flat with its split, without the twist. Checks use the nominal size, so a modeled thread inside its nut is not reported as a clash. Mass and volume come from the drawn solid.

The model above is the flange example. Drag it. The same table runs in Studio and through the MCP tools.