Q: I have a very old Astec CDH-3A machine. This machine was purchased in the early 90s and has been very reliable. However, recently I started to experience a strange issue. When I attempt to drill a hole, the process starts as normal, but when the electrode starts to spark on the part and the current ramps up, the electrode retracts to the top of the stroke. Can you offer some help diagnosing the cause of this issue? A: It's wonderful to hear that this machine has been reliable and is still in use. We have seen this symptom before. It's highly likely the MS-1 contactor is worn out. This contactor switches the AC power that feeds the DC rectifier for EDM power. When the contacts get worn or pitted, they do not make a good electrical connection. When current passes through them, they heat up causing a loss of electrical connection; hence, a loss of EDM power. The servo circuit sees the loss of EDM voltage and retracts. We do stock this part at our Michigan headquarters. Please contact us for part number CH-018. Q: We have several Maxicut MX-236 ZNC EDM Sinker machines. Each Sinker has light curtains on them for safety. The issue we're having is we use a rougher and then a finisher electrode and utilize the program hold function to stop the program after the last roughing step so the Operator can change the electrode to the finishing electrode. When the Operator reaches into the work area, the light curtain is tripped and the program is aborted. Is it possible to make this function work with the light curtain?
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