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A Couple Yaskawa Servo Questions

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  • A Couple Yaskawa Servo Questions

    There seem to be some very knowledgeable servo mavens here, and maybe you Yaskawa gents can give me some advice.

    I'm planning a semi-CNC conversion of a Southbend 13 x 40 to take over some of the drama with tapers, threading and shoulders. My plan is to use Yaskawa servos with EMC2, Servopack drives and Pico Systems PPMC cards to provide the analog velocity command required by my old but also NOS Sigma-class SGDA-04AS amps.

    Problem 1) is that my first choice for motors was in the attic, a pair of NOS SGMPH-040's. But these are Sigma II motors and apparently won't work w/ my amps. Their encoders don't have the usual A,B, C channel outputs--just a single pair called Data. Maybe the three channels are multiplexed or encoded into one? In any event is there a way to use these motors w/o buying new Sigma II amps?

    Problem 2) is that the second string motors are an SGMP 400 watt and an SGM 100 watt. I figure 1/8hp is enough for the cross slide. Besides this little motor has a lot of grunt; its got a 22:1 planetary reduction unit bolted to its face. That works out to approx 13ipm. So maybe I'll gear it up with some timing pulleys. But what I don't get is the connectors on the end of the power and encoder cables of these motors. They look like--but not exactly like--Molex MX150L pieces. They've got squarish black plastic hoods with yellow inserts and flat bladed pins in a two-row array. Yaskawa disclaims any knowledge of them, which I find strange because these motors came to me in full Yaskawa trade dress in unopened packages. If you're familiar with this type of connector, pls let me know. I hate to go to the trouble and expense of replacing them. Have you priced Amphenol parts lately?

    Problem 3) is that I could put the Yaskawa stuff back in its box and use some old but nice Sanyo Denki Super DC brush servos. One is a 400w Super R and the other a 180w Super U, both 75v w/ 1000 line incremental encoders. These are sentimental favorites; I just like their old-school look. But that'd mean buying amps and making a power supply. What would you do?

    Thanks very much in advance.

  • #2
    I would look at a Mesa 5i25 and a 7i77 analog card, I think it will be a lot easier to set up since there is a program that helps you along.

    Sigma IIs use serial encoders. No choice but to use SGDH amps, I use them in my laser welder.

    Typically Yaskawa uses generic rectangular connectors, they spec them in the manual. Sometimes OEMs specify a special connector and Yaskawa provides it to them. They usually will not talk about any special mods. Just look in the manual and order new shells and pins. They are really cheap.

    I would do something to kick the speed of the cross slide up, especially if you plan on tying it in to do threading.

    I would find drives for the sigma II motors. They have better performance as well as real time auto tune and more features in the sigmawin software. The Sigma II drives have positioning built in so you can use standard step/dir signals.


    • #3
      Let me make sure I understand what the Mesa 5i25 and 7i77 actually do. Something has to manage the connection of multiple Servopacks to the PC running EMC2 or one's favorite flavor. Something has to process data from the spindle encoders; the Servopacks only handle the motor encoders. Something has to manage the human machine interface, although if the PC was running a touch screen maybe no hardware required. And some hardware has to help with the home and limit switches, e-stop duties, spindle speed and direction messages to the VFD, etd. Presumably the 5i25 + 7i77 do these things. Maybe the 5i25 relieves the PC of certain computational burdens as well?

      Does the 5i25 require a dedicated PC to run, must it run in the same computer as EMC2, or what?

      I'd like to find Sigma II amps, but the pricing on eBay is not in the budget. Well, maybe if I sold off all the Sigma stuff I could swing the Sigma II purchases.


      • #4
        Originally posted by jackw19 View Post
        Let me make sure I understand what the Mesa 5i25 and 7i77 actually do.
        I believe they are to EMC as a smoothstepper board is to Mach III. The boards generate the signals to the motor and can do so at a much higher frequency than the PC's parallel port. The boards also serve as a breakout board.

        The Mesa boards would be driven by the EMC PC.

        I thought that EMC also supported the Pico cards?

        I have used neither, I'm still running directly off the parallel port, but a Mesa board setup is on my wish list for the next build. Either brand would do the job but Mesa seems more popular with EMC users.

        Re: your speed. 15 ipm should suffice for the X, but you'll want more speed for the Z if you intend to do threading.


        • #5
          Some of the fog is clearing now.

          Yes, Pico has a full lineup of servo and stepper products and good EMC support. I'm less familiar w/ Mesa, but they seem to get around.

          Z speed should be OK w/ the available 400w SGMP; the no-load RPM is 3000 at 200v. But in the real world it's got move a heavy carriage with an acme screw. What would be a reasonable timing belt ratio? 2:1, 3:1? With an 8tpi leadscrew 3:1 gives 125ipm.


          • #6
            I have done a few retrofits with mesa boards. The 5i25 is a PCI card that goes in the computer running EMC, the 7i77 is a daughterboard connect to the 5i25 via a db25 cable. The 7i77 handles 6 axis for servos, had 6 encoder inputs, 6 analog outputs for the amps, spindle control, 16 general purpose inputs and 32 general purpose outputs. It makes a retrofit extremely easy. No breakout board is required, the 5i25/7i77 handles that task as well.
            The 7i77 has analog outputs for 0-10V control to the servo amps, there is a extremely similar board, the 7i76 that uses step/dir instead for motion control. The two boards are quite similar.
            Additional daughterboards can be connected to the 5i25 as well if you require more capability.

            I have used smoothstepper boards with mach, the mesa hardware and Linuxcnc (EMC) is light years ahead of that setup. For starters, linuxcnc is extremely stable, none of the random strange behavior so common with mach. Secondly, with linuxcnc, there is almost no limit to the types of hardware than can be interfaced, its quite amazing. Support is extradordinay for both linuxcnc and the mesa boards.

            Pico is another company with interface boards for linuxcnc, although they do not have anywhere near the selection or user base of the mesa boards.

            I am doing a RF45 mill retrofit right now, with kelling brushless servos, AMC drives, mesa 5i25/7i77 boards. It will eventually have a 4th axis and a toolchanger, all easy to do with the mesa hardware and linuxcnc. Linuxcnc closes the servo loop back to the control just like high end commercial cnc machines, mach does not close the loop back to the controller, huge difference.

            Hope this helps a bit.



            • #7
              I did a 14x40 lathe a few years back with kelling 400W brushed servos (3000 rpm), ground ballscrews, and 3:1 belt drives. There was more than ample power and speed. The only mistake was using Mach3 for that retrofit. Mach has a lot of outstanding problems with lathe that go back years. A example of this would be constant surface speed, it does not work. Threading has been so-so at best with mach. Many other problems exist that "might" be fixed when/if Mach4 ever gets released and finally debugged into a working product some years down the road.


              • #8
                Thank you, posters. Your responses have helped a bunch.

                Wow--ballscrews. But maybe not for this old girl (1918) or at least not at this time. I do think I'll upgrade the cross slide screw to Acme; it originally is a V-form thread. I want to lengthen it and mount a bearing in the rear of the saddle so the X-motor can be located somewhat discreetly.

                One more Yaskawa question: My drives are SGDA-04AS and the quick start guide in the box says this particular model is for SGM class motors only. This is something of a disappointment since my would-be Z-motor is an SGMP-04. This same guide says the SGDA's require SGDA-04ASP, note the final character. But in the 450 page full-on manual, I see there's a user-settable flag for P (position mode) and S (velocity mode) and AS vs ASP on the nameplate just indicates the factory setting. Has someone here actually used an SGDA-AS amp with and SPMG motor?


                • #9
                  You should be able to use the P motor with drive. The P is just a pancake version of the longer, skinnier motor.

                  Loose the V-thread. You can buy pretty precise acme threaded rod and nuts from McMaster. I think it is good for .003 per foot.

                  I was going to do something similar on my Monarch. My plan was to use a high lead ball screw to drive the carriage. This was connected to the geared servo motor with a magnetic clutch. This way when it was not being used the screw could be easily back driven without the load on the motor. From the basic tests I did I did not even notice the additional load on the carriage hand wheel. For the cross slide I was going to make a sub-cross slide that mounted to the existing slide with a rear tool post. I was going to use a couple low profile THK rails for support and a small ball screw to drive it. This would make the machine usable manually without any changeover.

                  Ended getting my little hercus cnc lathe and retrofitting that. I use is about once every two years! I went with MachIII with that too. I regret that one too. Sometime it works, sometimes it won't. Sometime it will thread, sometimes it won't.


                  • #10
                    I have a problem with a control system that uses the Yaskawa SGDA 02AP200 Servopack driving a SGM02U3B4L motor. The problem is that intermittently while the servo is in run mode (observable on the JUSP-OP03A digital operator )the base block will kick in and switch off the servo with no given error code as to what the problem might be. I have eliminated the possibility that an external signal is shutting down the servo by setting CN-01 bit 0 to 1. This tells the servopack not to use the Servo ON input and instead keep the servo on all the time. The problem still occurs. I have also checked the mains power in case glitches may be causing the servo to switch off. But the mains power seems quite clean. Any help would be appreciated.


                    • #11
                      Im going to guess you have a bad servo drive is setting the bit does not stop it. Contact Yaskawa, they have good tech support.