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How do you accurately measure and probe the center of EDM drilling electrodes?

By  SST Consumables

January 14, 2024

Makino

Verifying and finding the center of an EDM drilling electrode can be a delicate and troublesome task, especially as the electrode diameters become smaller (0.5mm / 0.020” Ø or smaller). To find the center of a tube electrode, utilize a table ball within the machine’s work zone. Pick-up accuracy diminishes as the electrode is extended from the supporting Die Guide because the electrode begins to flex and bend the further it is extended.

To improve probing pick-up accuracy, use a ½ sphere table ball, as this minimizes the length that the electrode is extended away from the die guide. The image below shows the electrode extension length differences between a standard 10mm (0.400”) Ø table ball and a 10mm ½ ball sphere with a 0.5mm (0.020”) Ø electrode. In this example, using a ½ sphere ball, the electrode extension distance from the die guide is reduced by 60% and will improve the probing accuracy. As an added benefit, the flat-top surface of the ½ sphere ball will also provide a more accurate and better-qualified surface to establish Z-depth pick-ups.