I'm fixing up an IBC BoardMaker 2222, a 22" x 22" PCB engraver. So far I've replaced the Y axis with a McMaster-Carr 5/8" ball screw & nut, which had been a proprietary-threaded rod with self-adjusting anti-backlash (plastic) nut that self-destructed, and replaced the stepper drivers with Gecko G251's.
The machine uses a solenoid to move the spindle down until a wear-button hits the PCB, thus establishing the cutter height. Spring return. My question is about the solenoid drive. There are two identical circuits--both are logic-level in (from a db-25 parallel port) driving a relay that supplies +45V to the solenoid (i.e., they are in parallel), though one has a 5W 40 ohm resistor in series. (The solenoid is not identified, but has 70 ohm resistance.) This sounds to me like a way of driving the solenoid hard to move the spindle down, then holding it with reduced current. This is often done with a (big) cap across the current-limiting resistor. The solenoid doesn't move all the way down with just the "hold" current. I don't have the original control software, so don't know what the original software control signals look like. (IBC seems long gone, but may have had connections in the past with LPKF.) Does anyone have specific knowledge about what they intended as drive signals? I was tempted to replace the two circuits with just one, with an adjustable one-shot to drive the solenoid full, then a gated PWM to provide the holding current. (And replace those relays with a MOSFET.) But then I wondered if drilling or milling required a different set of timing than straight engraving? (In particular, I was imagining breaking a lot of 0.020" drill bits by driving full speed into the board.) Any ideas? Thanks. --Dale ------------------------------------------------------------------------------ Start uncovering the many advantages of virtual appliances and start using them to simplify application deployment and accelerate your shift to cloud computing. http://p.sf.net/sfu/novell-sfdev2dev _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
