Bolt & nut

A bolt or screw and the nut that threads onto it, from one standard size.

A bolt or screw plus, optionally, the nut that threads onto it — both derived from one designation, which is what makes them fit each other and real hardware. Picking M8 sets the 1.25 mm pitch from the ISO table rather than a typed guess, and a thread at the wrong pitch mates with nothing while looking perfectly correct in the viewport.

Everything around the thread follows from the size too: the hex is the ISO 4032 width across flats, the socket cap is the ISO 4762 head, the button head is ISO 7380 and the countersunk head is cut at the ISO 7046 90° (or, on an inch size, the ASME 82°) — so a flat head sits flush in a screw hole countersink of the same size instead of standing proud. The nut blank is bored at the tap drill before being tapped. The nut is tapped by subtracting the internal form of the same designation, which already carries the radial clearance a printed pair needs — so the bolt threads in instead of binding. The plain thread shape on its own is a solid threaded rod; use it when you want one thread rather than a matched pair.

The first turn is chamfered, and that is the detail a hand-built bolt misses. A thread that ends in a square face catches and cross-threads as you start it; a 45° lead-in guides it in straight. Sizes run M2–M8 plus the common imperial numbers — the range the hardware table holds real hex and head dimensions for, rather than a guessed one wearing a standard’s name. Both parts are ordinary primitives and booleans, so they stay parametric and re-open in the property panel.

Picking a head. Socket cap and hex are the driven ones. Countersunk sits flush, so use it wherever the head must not stand proud of a surface. Button is the low-profile rounded head — the same bearing face in less height. The thumb screw is the odd one out and the one worth knowing about: it has no standard behind it, so its knurled knob is proportioned from the thread rather than looked up — three times the diameter, never under 12 mm, because a knob you cannot turn with two fingers is not a thumb screw. That is the head to reach for on anything hand-tightened: a captive knob, an adjustable stop, a case someone opens without going to find a driver.

1. Open the Generate panel from the left sidebar and choose Bolt & nut (under Fasteners).
2. The bolt and its nut drop in as editable parts. The parameters open in the Properties panel, where you set them.
3. Pick the size — the designation sets the diameter and pitch together.
4. Set the thread length, then pick a head: socket cap, hex, countersunk, button, thumb screw, or none for a threaded rod.
5. Leave the nut on to get the matching nut beside the bolt.