Terry wrote: > Has anyone done an upgrade on a mid 80's Bridgeport mill with a Pro Trak > control? I have one that has Gentek DC servo's and amplifiers. The > machine has servo motors on all three axis and they work fine but I > would like a more modern set up. I have the schematics and manuals. The > manual says that the amps work using Pulse Width Modulation. I'm not > sure what it uses for signals. I have seen in forums that others have > used Mesa boards and EMC to retro older controls using the original amps > and motors. I am a Linux fan, I use it as my primary O.S., but no > expert. I am no electronics expert either. Others have made it sound > easy. Would a experienced machinist like myself be able to tackle this? > I make a complete lineup for systems like this. Those are Glentek servo amps? I assume the motors have tachometers? The servo amps almost certainly take +/- 10 V velocity command signals.
So, there are two paths. One is to keep the servo amps and use my PPMC board set which produces the analog command output. The basic set is $780, and provides pretty much everything you need. The other way it to get rid of the servo amps, and use my universal PWM controller and my PWM servo amps. That runs about $625. Really, the best way is to keep the servo amps if they are working well, you get smoother motion with a velocity servo than with the low-resolution encoders and no velocity info you'd get with the digital PWM servo amps. Mesa looks a lot cheaper at first than the Pico Systems stuff (my company), but they require daughterboards, breakout boards, cables, etc. so the price difference gets much less. You can check out my boards at http://pico-systems.com/oscrc4/catalog/index.php check the categories of PPMC and PWM Servo. Just to be sure, does this machine have digital encoders, or resolvers on it? (I can provide the hardware to go either way, but the encoders are simpler.) Well, converting a CNC machine with stepper motors is "easy", but there are limitations such as no position feedback to detect jams/crashes. Servos are a bit more complicated. The wiring is just a little more complicated, although if you keep the servo amps, it really isn't much more, you just need to be careful to not rip out what you intend to keep. But, then you have to "tune" the servo response. EMC2 has a LOT of helpful features, such as HalScope to help you do this, but you have to learn to use these facilities. When you get done, though, you have a machine where you can PROVE the responsiveness and accuracy of motion, and go back and recheck any time you think it may be misbehaving. I am using the PPMC on my Bridgeport mill. It was a manual mill, and I had to adapt ballscrews and motors to it. Machining skill may not be greatly useful here, it will be mostly wiring and tweaking the configuration files. At least you don't have to fight the Linux learning curve, that's what stops so many Windows users. Jon ------------------------------------------------------------------------------ This SF.net email is sponsored by Sprint What will you do first with EVO, the first 4G phone? Visit sprint.com/first -- http://p.sf.net/sfu/sprint-com-first _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
