Electronic edge finders work in a similar way to mechanical edge finders. However, the location of an edge is indicated by an LED light rather than by the probe of the device becoming offset. Another difference is that the spindle of a machine does not need to be rotating for the electronic edge finder to work.
Some electronic edge finders work when an electrical circuit is completed. The circuit is completed through the workpiece, table and spindle of the machine it is used with (drill press or milling machine). Because of this, they can only work locate the edges of parts that are made out of an electrically conductive material (metal).
There are also more complex devices that have an internal ‘tickler’ mechanism which, when disturbed by the contact with the workpiece, closes a circuit internal to the edge finder. These edge finders do not depend on electrical conductivity through the machine and so can be used with parts made of non-conductive metals.
Laser edge finders
Laser edge finders are arguably a lot easier to use than other electric or mechanical edge finders. The device projects a fine beam that indicates the edge of the part.
The user moves the beam to the edge of the work and then sets one of the axes on the DRO to zero. It is not necessary to half the diameter of the edge finder to find the true edge of a part.
Although electronic edge finders can be used to more accurately locate the edge of a part in comparison to mechanical edge finders, they do have some disadvantages. They are more fragile and if they are dropped, are more likely to break than the hardened steel mechanical edge finders.
As the LED light gradually lights up, it does not indicate a clear point of contact. This can some result in the edge finder overrunning past the edge and providing inaccurate readings on the digital read out. It is for this reason that many people prefer to use mechanical edge finders.