Cut a hole for a socket, switch or fan

Ready-made openings at the dimension the datasheet gives — USB, IEC, XLR, rocker switches, fans, LCDs.

A front panel is mostly holes, and every one of them is a number somebody else already decided. A USB-C plug is 8.4 × 2.6 mm, an M12 pushbutton wants a 12 mm bore, an 80 mm fan bolts on 71.5 mm centres. Get one wrong and the print is scrap, because a connector opening is the one feature you cannot ease open with a knife once the part is cold. So OwlCAD ships the openings as ready-made shapes and you place them instead of measuring them.

They are ordinary solids, not red cutters. This trips people who met the Fasteners group first, where Screw hole and Nut trap arrive tinted red because they are tools. A panel cutout arrives as a plain body the same colour as everything else. It behaves like one too — move it, rotate it, duplicate it, subtract it. The only thing that makes it a hole is what you do with it.

They stand up, and your wall probably does not. Each cutter is built 12 mm tall with its opening facing the sky, because that is the orientation that cuts a lid. Most openings are in a *side*, so the first thing to do is rotate it 90° about X or Y and point the opening out through the face. It is the single most common way to end up subtracting a neat rectangular trench down through the top of an enclosure instead of a port in its end.

Overshoot the far face. Twelve millimetres is generous for a 2 mm wall on purpose: the cutter has to emerge on the other side. Landing it exactly flush is the same defect a vent has when its depth matches the panel — the boolean leaves a film a layer or two thick, it renders as a closed face at any zoom, and you find it when the plug will not go in. Push it through until it visibly sticks out both sides, and switch on X-ray if you want to be certain.

The number is the plug, not your printer. These are the published mating dimensions with no shrinkage allowance folded in, which is deliberate — a fudge factor baked into the part would be a guess about a machine we have never seen. If your first print comes out tight, that is a clearance to add, not a specification to bend. Add it once, in the direction your printer actually errs, and every cutout in the file moves with it.

A fan cutout brings its screw pattern with it. Pick the 80 mm one and you get the Ø76.3 opening *and* the four Ø4.3 holes on 71.5 mm centres, from the same published table the fan frame generator builds its frames from — so a hole you cut here accepts a fan you generated there, and both accept one you bought. The LCD, OLED, XLR and D-sub cutouts carry their mounting holes the same way, which is why their overall footprint is wider than the window you can see.

What the catalogue cannot do is look at your panel. Crowd a 22 mm button against a corner radius, or put two glands a millimetre apart, and the geometry is perfectly valid and the part is fragile. That is what the print check is for — run it once at the end, when every opening is cut.

1. Open the Shapes panel and type the connector into the search box — "USB-C", "rocker", "fan", "gland". Matches from the parts library appear below the shapes under From the library; Library → Maker → Enclosure & Panel lists the whole set.
2. Click one and it drops in as an ordinary solid, already cut to the connector's published opening. There is nothing to type: a USB-C cutout is the 9.5 × 3.5 mm obround the plug needs, an IEC C14 inlet its 27 × 19.5 mm opening with 3 mm corners.
3. Every cutter stands 12 mm tall with its opening facing up, so it cuts a lid or a base as it lands. For a side wall, rotate it 90° first, so the opening looks out through the face you are cutting.
4. Move it until it breaks clean through the wall and stands proud on both sides. A cutter stopping flush with the far face leaves a skin over the opening, and nothing on screen shows it.
5. Select the panel first, then the cutter, and Subtract — subtract keeps the FIRST body. Press Flip order in the Properties panel if the panel vanishes and you are left holding the cutter.
6. Repeat for every opening, then run the print check — a cutout crowded against an edge leaves a wall this catalogue cannot see, and export when it is clear.