How we draw a box: parts, codes and the numbers that mean the same everywhere

One box, five parts

Strip a fitted wardrobe or a kitchen of its doors and you are looking at a row of boxes. Ours are 18 mm board throughout. The two sides run the full height. The top and the bottom sit between the sides, not on them, so the side takes the weight down to the plinth in one piece. The back sits between the sides too, behind the top and bottom, screwed every 300 mm through the sides. Four confirmat screws hold each joint of the sides to the top and bottom.

Before the back goes on, both diagonals are measured and must agree within 2 mm. The back then locks the square in. A box that is out of square never closes its doors with even gaps, and no hinge adjustment fixes that.

The code on every part

Each box takes a letter in the order it is fitted, A, B, C from the left. Each part takes a number that means the same in every box, and a hand where it matters. Shared groups take their own letters: P for the plinth, T for the top boxes, F for the fillers scribed to the walls, G for glass doors ordered from a door maker. The same code sits on the box sheet, the cut list and the cutting plan in the same colour, and the workshop writes it on a hidden edge of the part as it comes off the saw.

How sizes are written

Millimetres, bare numbers, length by width, thickness in its own column. For a door or a drawer front the length is the height. Every size is the finished size with the edge banding on, so a side written 1940 by 598 measures that on the bench, banding included. Box sizes are written width by height by depth. Heights are given from the finished floor with a plus sign, so a rail at +1972 has its centre 1972 mm above the floor you stand on.

Two words carry a lot. Clear is the inside of an opening. Outside is the box. A bay 560 mm outside is 524 mm clear, because two 18 mm sides are in the way. Drawings label both so nobody has to subtract on site.

A real bay, from our engine

Our workshop does not size parts by hand. The rules live in an engine that takes a recess and a list of bays and returns every part, and its tests pin it to the wardrobes we have built. Here is box A of a 2400 by 2600 by 600 mm recess split into four bays of 560 mm: the long hanging bay with shoe shelves.

Drill everything before the box is closed

Hinge plates, the rows of shelf pin holes, rail brackets and drawer runners are all drilled on the flat part, measured from that part's own bottom or front edge. The pin rows sit 117 and 497 mm from the front edge with a hole every 32 mm, which is the 32 mm system that every hinge and runner maker builds to. Shelves stop 80 mm behind the box front so the door and its hinges clear them, and they are 500 mm deep against the back.

Hinge plates go on a line 37 mm from the front edge of the side. The first and last hinges sit 100 mm from the door ends and the rest are spaced evenly, with one more hinge when a door passes about 25 kg. The door maker confirms weight, hinge count and plate type before the sides are drilled, and sends a drilling template.

Source: Wikipedia: 32 mm cabinetmaking system

Why a fitter needs pictures, not paragraphs

The crews who build and fit from our sheets read English, Hindi or Urdu and often have little schooling. The first packs we made were told to our face that they were unclear and too complicated. So every sheet now has one job: the box from the front without its door, part bubbles with numbers, heights from the floor, the box from above, and the build steps as four pictures in the order the workshop works. Drill, join the bottom and top, add the back and check the diagonals, then shelves and rails. The reasons for the rules live in guides like this one, not on the crew sheets.

If you build your own box from this, keep the same discipline: one letter per box, one number per part, finished sizes, and drilling before assembly. Then read edge banding and grain direction, and see how a whole bookcase becomes a board order in what to order for a bookcase.