What Are Angle Plates?
A very useful tool when it comes to work holding or alignment is the angle plate. An angle plate is simple a device with two flat surfaces at right angles to each other. The inside surfaces of an angle plate can either be the rough surface from when it is cast or they can be machined to be flat and parallel to the outer surfaces.
Angle plates are usually made from cast iron or steel. The end surfaces are always machined to be flat and square. Large angle plates often have a web at the end unless they are machined on the inside in which case they are never webbed.
Angles plate might have two flat surface with no holes or slots in them at all. In this case it is up to the user to make whatever holes etc he finds useful. Otherwise an angle plate might have various patterns of holes and slots and T-slots that can be used for holding the angle plate to something or for holding workholding devices or workpieces onto the angle plate.
What are angle plates used for?
The main purpose of the angle plate is that it effectively rotates one surface, for example, a milling table, into another surface at right angles to the first.
If a work piece is clamped to an angle plate, it effectively rotates it through 90º. When a flattish work piece is clamped to the milling table it is usually with the large surface horizontal. In this position it is not always easy to machine the sides of the work piece as might be required. But if we use an angle plate to turn it through 90º we can easily machine the sides.
Similarly it is possible to hold a long thin work piece on end on an angle plate. It is then possible to machine the end of the work piece.