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  • Stepper controller recommendations?

    Well, I got my CNC lathe controller up and running.... aaaaaannnd it looks like one of my stepper drivers is bad.

    It'll turn the stepper at slow speeds, 50% jog, etc. But try full speed jog, and it just sits and buzzes. It'll jerk a little as you press the key, but that's it.

    I tried switching the cable between steppers, and it moved to the other stepper, so it seems the driver itself is bad. Maybe not entirely, but it's sure not happy. That's what I get for buying used equipment...

    Anyway, can anyone recommend a good replacement? I have a 36V 10A power supply, and bipolar (four-wire) 270 and 570 oz-in steppers. I don't need much more than 1/4 or 1/8 step.

    Looking for a good reliable brand at a decent price.

    Doc.
    Last edited by Doc Nickel; 06-25-2016, 05:45 AM.
    Doc's Machine. (Probably not what you expect.)

  • #2
    Glad you finally got it going! Have you taken the cover off & had a look around? That looks like a solid controller & probably has replaceable components. It's been around long enough that someone, somewhere has had the same problem and has posted a fix if you try the right search terms. Usually the same weak spots show up after an operator error like unplugging it with the power on or incorrect wiring or whatever happened before you got it.

    Just because it's not the latest whiz-bang modern controller doesn't mean it's not worth using. Heck, both of my controllers were made in 1996 and are still making very accurate parts.
    Milton

    "Accuracy is the sum total of your compensating mistakes."

    "The thing I hate about an argument is that it always interrupts a discussion." G. K. Chesterton

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    • #3
      The box has been open. I've been playing with the wiring for weeks now.

      No, there are no replaceable components, at least not without a fine-tipped soldering iron or a hot-air rework station. A cursory glance doesn't show anything visible and obvious (burnt trace, popped or bulging caps, smoke trail, etc.) and I am definitely not familiar enough with electronics to try and troubleshoot a detailed board like this.

      A Google search returns remarkably few hits- three pages, many of which are Chinese suppliers. The two threads I found in which people had problems with machines using these cards, had problems other than the cards themselves.

      Microkinetics still carries this controller, I suppose it'd be easiest just to buy a fresh one. That way I don't have to re-futz with the wiring and it is sure to fit in the same enclosure.

      Doc.
      Doc's Machine. (Probably not what you expect.)

      Comment


      • #4
        Have you checked out Gecko? US made and support.
        Max.

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        • #5
          Doc, are there motor torque settings that you can change on the programming of the cards? Perhaps the load on whichever axis you have it on is exceeding the setpoint. Jim

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          • #6
            Originally posted by Doc Nickel View Post
            Looking for a good reliable brand at a decent price.
            Then the obvious one is Leadshine controllers. I believe they have a sales office in USA too.
            Amount of experience is in direct proportion to the value of broken equipment.

            Comment


            • #7
              Originally posted by jmm03 View Post
              Perhaps the load on whichever axis you have it on is exceeding the setpoint. Jim
              Very good point Jim, bet'cha you get the prize! The manual states the default is .5A, just enough to cause the symptom. Doc's purty smart though & may have already checked it. We'll wait & see. Maybe he'll send you some moose steaks.
              Milton

              "Accuracy is the sum total of your compensating mistakes."

              "The thing I hate about an argument is that it always interrupts a discussion." G. K. Chesterton

              Comment


              • #8
                There's a current setting, yes, but I tried changing it- both minimums and maximums. No difference.

                Plus, I'm just in the testing stage- both motors are disconnected, it's just the steppers sitting there turning. Zero load.

                I was in fact looking at the Gecko line, since from what I can tell they're pretty popular. I have to admit, though, I still don't entirely know what I'm looking for, and I've already bought way too much stuff for this thing, that was either unnecessary, wrong, or unusable. (Steppers, power supplies, that signal generator, antique controllers, ballscrews that proved to be too big or too small, wire that's the wrong gauge, etc, ad nauseum.)

                I played it safe- for varying degrees of "safe"- and ordered another Microkinetics card. It was about the same cost as a Gecko, and at least I'm already familiar with the wiring- and I won't have to redrill my enclosure or anything.

                Doc.
                Doc's Machine. (Probably not what you expect.)

                Comment


                • #9
                  When bench testing steppers, hang a drillchuck on the bare shaft

                  Originally posted by Doc Nickel View Post
                  There's a current setting, yes, but I tried changing it- both minimums and maximums. No difference.

                  Plus, I'm just in the testing stage- both motors are disconnected, it's just the steppers sitting there turning. Zero load.

                  I was in fact looking at the Gecko line, since from what I can tell they're pretty popular. I have to admit, though, I still don't entirely know what I'm looking for, and I've already bought way too much stuff for this thing, that was either unnecessary, wrong, or unusable. (Steppers, power supplies, that signal generator, antique controllers, ballscrews that proved to be too big or too small, wire that's the wrong gauge, etc, ad nauseum.)

                  I played it safe- for varying degrees of "safe"- and ordered another Microkinetics card. It was about the same cost as a Gecko, and at least I'm already familiar with the wiring- and I won't have to redrill my enclosure or anything.

                  Doc.
                  Steppers don't like no inertia. Or even mismached load, motor inertia and drive settings. "good" drives even provide "skip" frequencies for when the hardware just can't be changed and harmonics conspire to stall the stepper.

                  Bottom line, high speed on the bench can be difficult. put some mass on the motor shaft.
                  I use th Parker S6 and S8 drives. There is lots of good information available to download from Parker.

                  Comment


                  • #10
                    Originally posted by CalM View Post
                    Steppers don't like no inertia. Or even mismached load, motor inertia and drive settings.
                    -To clarify, I have two steppers, both by the same manufacturer. One's a 270 oz-in, the other is a 570 oz-in. Both are wired using a 4-prong plug. With driver A plugged into stepper A, and driver B plugged into stepper B, A does not "lock" at idle (low holding torque) and does not like turning at high rates of speed. B "locks" normally, and turns properly at both low speeds and high.

                    Swapping wires so driver A is connected to stepper B, and driver B is connected to stepper A, now stepper B has weak holding torque and doesn't like high speeds, while stepper A locks firmly and spins nicely at all speeds.

                    In all cases the steppers are just sitting there, with nothing but a small belt pulley on the shaft.

                    Doc.
                    Doc's Machine. (Probably not what you expect.)

                    Comment


                    • #11
                      If the steppers turn at all with the "bad" driver, it sounds more likely that there is a "settings" issue than a bad driver. All the power hardware would seem to be basically working, no shorted transistors, etc.

                      How is the holding current set? A fixed percentage, or a separate setting?

                      If the stepper won't go fast, then it would seem that it's not getting hit with enough voltage, or the current limit is set low. If it is a fixed percentage for hold, then it sounds even more likely that the drive current is set too low, because both drive and hold would be low by the same proportion.

                      Yes, that CAN be a hardware problem, typically a simple one, if the current limit circuit has a bad solder joint etc. Something that makes the current limit at too low a level. This can be an issue with drives that use a replaceable resistor to set curent, because a bad connection or wrong resistor can make the thing limit way early.

                      With higher step speeds, the drive current has to build up fast, which means there must be enough voltage to drive the current into the stepper inductance, If the current limit is too low, the driver will not be able to apply enough voltage (the "volt-seconds" will be too low to get appropriate torque).
                      Last edited by J Tiers; 06-25-2016, 04:43 PM.
                      CNC machines only go through the motions.

                      Ideas expressed may be mine, or from anyone else in the universe.
                      Not responsible for clerical errors. Or those made by lay people either.
                      Number formats and units may be chosen at random depending on what day it is.
                      I reserve the right to use a number system with any integer base without prior notice.
                      Generalizations are understood to be "often" true, but not true in every case.

                      Comment


                      • #12
                        Originally posted by Doc Nickel View Post
                        -To clarify, I have two steppers, both by the same manufacturer. One's a 270 oz-in, the other is a 570 oz-in. Both are wired using a 4-prong plug. With driver A plugged into stepper A, and driver B plugged into stepper B, A does not "lock" at idle (low holding torque) and does not like turning at high rates of speed. B "locks" normally, and turns properly at both low speeds and high.

                        Swapping wires so driver A is connected to stepper B, and driver B is connected to stepper A, now stepper B has weak holding torque and doesn't like high speeds, while stepper A locks firmly and spins nicely at all speeds.

                        In all cases the steppers are just sitting there, with nothing but a small belt pulley on the shaft.

                        Doc.
                        If I understand your procedure correctly, you are driving both a 270 oz-inch and a 570 oz-in motor with the same settings from the same drivers and getting "acceptable"performance from one of the drives, but not the other.

                        That can't be right, A drive customarily will not share settings across such a large motor variation.

                        Comment


                        • #13
                          There are only three possible settings on each controller, set with a DIP switch bank. The first one is the microstepping- you can choose full step, half step, quarter step or eighth step.

                          The second is current limiting. It'll knock back holding current at idle after a half second. The "bad" driver acts exactly the same on either setting.

                          And the third is current limit. As noted in my earlier post, I tried it with this setting both minimized and maximized, plus a couple random settings in between. Again, no change, zero difference in how the 'bad' one acts.

                          There are no removable components on this board, and it's mostly tiny surface mount hardware, so trying to patch or replace something would almost require a hot-air rework station, which I don't have.

                          If there's a bad solder joint or bad component, I can't spot it visually, although I admit I haven't dismounted the board and stuck it under a microscope either.

                          That can't be right, A drive customarily will not share settings across such a large motor variation.
                          -Maybe not in use, but I'm just turning an unloaded stepper. Both steppers are well within the voltage and amperage capacities of the drives, and said drives should be able to run them fairly well even at minimum current settings. But one of the two can't even drive the smaller stepper, when set at maximum current settings.

                          Doc.
                          Doc's Machine. (Probably not what you expect.)

                          Comment


                          • #14
                            I'd suggest biting the bullet and investing in reputable drives. They may appear costly at first, but when you add up the time you're spending troubleshooting........

                            I have a few of these;

                            http://www.geckodrive.com/geckodrive...ves/g203v.html

                            And I think they are great. The "indestructible" design sounds particularly well suited for your beginner's level of experience with these things.
                            I've got plenty of experience and still manage to blow things up, but my Gecko's are doing just fine.

                            I also like Gecko's manuals and support.

                            There are number of other options, such as the TB6600 drives, etc., very cheap, but with some things you do get what you pay for.

                            Comment


                            • #15
                              OK.

                              The "tiny" components are not that hard with practice, as I do them with a fairly standard iron. Things more than a size smaller than an 805 can be an issue, though.
                              CNC machines only go through the motions.

                              Ideas expressed may be mine, or from anyone else in the universe.
                              Not responsible for clerical errors. Or those made by lay people either.
                              Number formats and units may be chosen at random depending on what day it is.
                              I reserve the right to use a number system with any integer base without prior notice.
                              Generalizations are understood to be "often" true, but not true in every case.

                              Comment

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