The important thing to remember before cutting pipes is to plan ahead.
Have you given consideration to ensuring that earth bonding continuity will not be broken?
Is the water disconnected?
Where are the pipes to be positioned?
Do I have all the equipment and materials to finish the job?
Is there anywhere I can get extra material from should the need arise?
Measuring the pipe
Copper is a relatively soft material which can easily be cut with a hacksaw.
When measuring the position of a cut, make sure you allow enough for the pipe to sit fully into the joint. If you look inside fittings, you will generally see a slight ring where the inserted pipe will butt up to. If you’re not sure, try pushing a piece of pipe into a fitting until it is fully home, then mark the pipe with a pencil at the end of the fitting. When you withdraw the pipe you can measure the extra length from the mark to the end of the pipe.
Marking and cutting the pipe square
Mark the pipe where it needs to be cut. It is important to cut it square. Since hacksaws have a tendency to wander, the best answer is to use a paper guide. Take a piece of paper with a straight edge and wrap it round the pipe at the mark. By wrapping it around on itself, it should automatically form a straight guide which is square to the pipe. Hold it in place and make your cut alongside it.
Cutting copper with a pipe cutter
Better still, use a pipe cutter. This consists of a cutting wheel in an adjustable grip with rollers mounted opposite. The cutter can be unwound to fit over the pipe then screwed back up so that the wheel sits against the mark. The tool can then be revolved around the pipe, tightening it after each turn. As the tool is tightened and revolved, the wheel cuts through the pipe at right angles.
Once the cut has been made, clean off any burrs (pieces sticking out) with a small file or emery paper.