How to Find a Vertical Line
Plumb-bobs are machine-made, round-section weights which can be bought from most tool merchants. When tied to a builder’s line or string and suspended from a pin or nail, a true vertical is struck by the line when the weight stops swinging.
By mounting the line and plumb-bob on to a board, the vertical line can betaken from the edge of the board with a pencil.
Make the board 100 x 25 mm. (4 x 1 in.) and 1500 or 1800 mm. (5 or 6 ft) long. Cut a hole 12 mm. (1/2 in.) longer and 50 mm. (2 in.) wider than the bob for it to swing in, and mark a centre line up the board. Fix the pin into the centre line near the top of the board.
A bob can be made by hammering a piece of lead into an even shape.
When using a bob and board, make sure that the line swings free of the board.
Marking a horizontal without a spirit level
Make a thin ply pointer with a pin hole at the top and a point at the bottom, both exactly central to the edges of the ply. Firmly fix an upright board, wider than the pointer, to a straight-edge and draw a centre line through the board at 90° to the base of the straight-edge. Loosely pin the pointer to the board through the centre line, so that the pointer swings freely. Rest the straight-edge on top of the object to be levelled and move the object until the pointer lines up with the drawn centre line.
Fit a clear plastic tube into each end of a length of hose-pipe. Pour in water, ensuring that there are no air bubbles, until water shows in the plastic fittings. The water in the two fittings will be level — a useful guide for checking round a corner without a spirit level.
To check the level of a worktop or flat surface, stick a line of coloured tape along one side of a long glass dish, parallel to the bottom. Put water in the dish to a level just above the tape. Stand the dish on the surface to be checked. When the water level is exactly in line with the tape edge, the worktop surface is level.