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Does anyone know the price an encoder that would
work on this machine with emc and not made out of gold? Will the geckos run these motors? and are they good with emc? I am trying to get an idea of the cost to retro fit it. Andy Ray Henry wrote: I started servicing CNC machines a couple years before this machine was made. I never saw a stepper used for axis positioning until much later. They were used to pace the tape through a tape reader during that time.Let's assume that you've got servos. Next issue is the nature of the position feedback. Many of the machines from the the seventies and eighties used resolvers rather than pulse coders. A resolver does not produce pulses that can be counted. A resolver uses ac rather than dc power. They take two ac signals, sine and cosine to each other and return the rotor position as a phase shifted signal. My experience suggests that one way you can tell a resolver is that the six wires from it were twisted in pairs. If it was placed in a can with a plug, good luck figuring it out. (This is where a wiring diagram would be a real help) Assuming resolver feedback there are a couple things you can do. The first is get a resolver to quadrature converter box. With such a box you get the signal generator to power the resolver and a fixed number of pulses per rotation of it. You could also replace the resolver with an encoder. This is what MattS and I did with a Hardinge lathe. He had a little spindle built that matched the size and arrangement of the Harosun(sp) resolver and mounted a shaft encoder on top of it. Okay. Let's say now that you've got quadrature feedback of axis and spindle position. Now you need a way to get those signals into the PC running EMC2. Several board makers have devices that can do this. EMC has HAL driver modules that can read these. In alphabetical order, some of these include. Mesa, Pico, Pluto, STG, Vigilant, Vital. You'll find links to these companies at www.linuxcnc.org. And lastly you will have to produce a velocity signal of the sort expected by the motor's drive amplifier. In that age most of the drives used an analog signal that varied between -10v and +10 volt. Again the board makers will usually have that ability as well. HTH Rayh On Tue, 2007-05-15 at 15:19 -0500, Andy Holcomb wrote: |
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