A spiral staircase is a great space-saving idea and introduces the problem of creating a curved staircase handrail.
The Tauring Machine
The simplest way to form a metal spiral staircase handrail is to use a computerized tauring machine. These machines are capable of bending many different types of metal. For a stair handrail you would probably choose to use a box section with a suitable profile, semi-circular for example. The tauring machine is set up using the radius of your staircase.
Setting up and Forming
The tauring machine uses a series of drive rollers which are set out on the work bed to achieve the degree of bend required. The handrail metal is fed into the rollers and then pulled through them to form the perfect arc.
You need to know the radius of your hand rail and have two options when using wood.
A handrail can be carved, using a spoke shave. To mark the circumference, use a compass. Cut out the radius with a coping saw or a jig saw and finish off with the spoke shave. Once the circumference is carved you can scribe the depth of the handrail, cut and finish with the same tools.
You can form the handrail and bend it by using a steam bath and gentle pressure. In bending it is important you wear gloves to protect yourself from the heat.
The parts of the handrail can be fitted--using handrail brackets or by being welded or joined to the uprights on the stairs.