CAD prompt examples

Create a 100 by 60 mm rectangular plate, 4 mm thick, with four 5 mm diameter through holes positioned 10 mm in from each corner, and 2 mm fillets on the outer corners.

Corner inset is given explicitly, so the hole pattern is unambiguous.

Create a 120 by 80 mm panel, 3 mm thick, with a 6 by 4 grid of 8 mm diameter ventilation holes centred on the panel with 4 mm between hole edges, and four 4 mm mounting holes 6 mm in from each corner.

Describing spacing between hole edges rather than centres avoids overlap on tight patterns.

Create a flat washer with 20 mm outer diameter, 10.2 mm inner diameter, and 1.5 mm thickness.

The bore is 0.2 mm over the nominal 10 mm shaft, which is the clearance, not the shaft size.

Create an L bracket with 60 mm and 40 mm legs, 30 mm wide, 4 mm thick, with two 6 mm diameter holes in each leg spaced 20 mm apart and centred on the leg width, and a 4 mm fillet at the inside corner.

The inside fillet matters structurally; state it rather than hoping for it.

Create a pillow block bearing housing for a 22 mm outer diameter bearing, with a 60 mm by 30 mm base, 45 mm total height, 12 mm base thickness, and two 6 mm mounting slots 44 mm apart.

Slots rather than holes give you adjustment during assembly.

Create a cable clip for 8 mm diameter cable, 12 mm wide, 2.5 mm wall thickness, with a C shaped opening of 6 mm and a flat back with one 4 mm countersunk mounting hole.

The opening is narrower than the cable so the clip grips it.

Create a standard metric involute spur gear with 23 teeth, module 2 mm, 20 degree pressure angle, a 10 mm centre bore, and 8 mm face width, with small root fillets and side chamfers.

Module and tooth count define the size; do not also specify a diameter or they will conflict.

Create a GT2 timing belt pulley with 20 teeth, 6 mm belt width, a 5 mm centre bore, 16 mm total height including a 6 mm tall hub, and 1 mm flanges on both sides.

Flanges keep the belt tracking; the hub gives room for a grub screw.

Create a rigid shaft coupler, 25 mm long and 20 mm outer diameter, with a 5 mm bore at one end and an 8 mm bore at the other, and two M3 grub screw holes per side positioned 90 degrees apart.

Different bores per end is the common real case; say so explicitly.

Create a rectangular enclosure base, 100 by 70 mm external and 40 mm tall, with 2.5 mm walls, a 3 mm floor, four internal corner bosses 6 mm in diameter with 2.5 mm pilot holes for self tapping screws, and a 2 mm lip around the top edge.

Bosses and a lip are what make an enclosure assemble; a plain box will not.

Create a panel mount adapter plate, 50 mm square and 3 mm thick, with a 22.5 mm central hole for a switch, four 4 mm mounting holes on a 40 mm square pattern, and a 1 mm chamfer on the central hole.

Bolt patterns read most clearly as a pitch circle or a square pattern with one dimension.

Create a hexagonal standoff, 25 mm long across 7 mm flats, with an M4 threaded hole through the full length and 0.5 mm chamfers on both ends.

Chamfers on threaded ends stop the first thread from burring over.