Tolerances

A tolerance describes or limits how far off the exact size a part may be before it is rejected. Tolerances are especially important when parts are designed to fit together, for example if a pin is too big it won't fit into a hole but if it is too small it will rattle around.

Tolerances are shown on drawings and there will be different tolerances for different part and processes and there is usually an upper and a lower limit on size. The two limits are usually the same above and below but in certain situations they can be different.

For the Metalwork course there are set tolerances for different processes, you should be aware of these to make sure you are producing work that is accurate enough.