On The Lathe
Woodturning is a form of woodworking that is used to create wooden objects on a lathe. Woodturning differs from most other forms of woodworking in that the wood is moving while a stationary tool is used to cut and shape it. Many intricate shapes and designs can be made by turning wood.
There are two distinct methods of turning wood: spindle turning and bowl or faceplate turning. Their key difference is in the orientation of the wood grain, relative to the axis of the lathe. This variation in orientation changes the tools and techniques used. In spindle turning, the grain runs lengthways along the lathe bed, as if a log was mounted in the lathe. Grain is thus always perpendicular to the direction of rotation under the tool. In bowl turning, the grain runs at right angles to the axis, as if a plank were mounted across the chuck. When a bowl blank rotates, the angle that the grain makes with the cutting tool continually changes between the easy cuts of lengthways and downwards across the grain to two places per rotation where the tool is cutting across the grain and even upwards across it. This varying grain angle limits some of the tools that may be used and requires additional skill in order to cope with it.
In spindle turning, the wood is fixed between 2 points. The spur center digs into the wood and is powered by a motor. The other, a hard center or a live center may be a point or set of points in the tail-stock. In face plate turning, the wood is secured with screws to a faceplate or in a chuck or jig. the tail stock and a center may also be used for added support on large pieces with a faceplate. Most bowls, platters and many vessels are face plate turned, while pens, furniture legs, spindles, and some vessels are spindle turned. The method used may differ depending on the shape of the blank and the technique of the turner, and both methods may be used on the same piece. When wood is cut in such a way that the fibre being cut is not supported by the fibre below it, it tends to separate and tear. This ‘tear out” exhibits a rough, highly damaged looking surface texture and greatly reduces the value of any product exhibiting it. The direction of cut is different in spindle turning and faceplate turning because cutting in the wrong direction can cause tear out. Spindle turning cuts are made from high points toward the axis on the outside of the piece, and from the axis toward the outside when hollowing. When faceplate turning, the opposite applies.