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IndustryArena Forum > CNC Electronics > Stepper Motors / Drives > Interpreting Opinions for Gecko vs Cheap Drivers
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  1. #21
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    Re: Interpreting Opinions for Gecko vs Cheap Drivers

    No, I haven't. I have 4 of them sitting in a drawer.
    Gerry

    UCCNC 2017 Screenset
    http://www.thecncwoodworker.com/2017.html

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    http://www.thecncwoodworker.com/2010.html

    JointCAM - CNC Dovetails & Box Joints
    http://www.g-forcecnc.com/jointcam.html

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  2. #22
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    May 2014
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    Re: Interpreting Opinions for Gecko vs Cheap Drivers

    It seems to me that no one answered the OP question. WHY are the better drivers better? The closest thing I saw was:

    Features like stall detection, anti resonance, full step morphing, and many others.

    So, for each of these features, it makes sense to ask - Why is this a good feature? What are the benefits of having these feature, or potentially, the adverse consequences of not having the feature? It seems that was what the OP was about, but he tended to get exactly the sort of answer he wasn't looking for.

    For a DIY builder, it is nice to know *what* compromises are being made, not merely *that* compromises are being made.

  3. #23
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    Re: Interpreting Opinions for Gecko vs Cheap Drivers

    Personally I would not buy a G540. Stick to independent stepper drives. Gecko are still not anywhere near the Ferrari garage when it comes to the top end of drives. I'm still a loss to understand why they are so higly rated. If you upgrade to more industrial quality controls, you will have issues due to nonstandard features that are oprtiised for a Mach3 environment. I've not used Leadshine, I would suggest for a hobbiest, I'd go that way but would not be tempted by a parallel port all in one. Keep them seperate.
    Rod Webster
    www.vehiclemods.net.au

  4. #24
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    1662

    Re: Interpreting Opinions for Gecko vs Cheap Drivers

    Quote Originally Posted by rodw View Post
    Personally I would not buy a G540. Stick to independent stepper drives....... Keep them seperate.
    Small technical quibble. The drives plug in to the board. They can be run stand-alone if desired ... but that kind of defeats the purpose of paying for the rest of it.

    At the time the G540 was released Gecko had a reliability and durability advantage over the direct competition. Those things were and still are important to me. The competition has upped their game in the meantime. I wouldn't choose a G540 if buying today.
    Anyone who says "It only goes together one way" has no imagination.

  5. #25
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    Re: Interpreting Opinions for Gecko vs Cheap Drivers

    So, for each of these features, it makes sense to ask - Why is this a good feature? What are the benefits of having these feature, or potentially, the adverse consequences of not having the feature?
    stall detection - If one motor stalls, the drive can notify the control software to stop all the motors, minimizing or preventing damage to your parts

    anti resonance - Allows motors to run smoother, and potentially faster without stalling. Resonance can result in very rough running, which can lead to stalling.

    full step morphing - Give more torque at higher speeds


    The simple answer is that better drives will run cooler, quieter, and with more power than cheap drives.



    Gerry

    UCCNC 2017 Screenset
    http://www.thecncwoodworker.com/2017.html

    Mach3 2010 Screenset
    http://www.thecncwoodworker.com/2010.html

    JointCAM - CNC Dovetails & Box Joints
    http://www.g-forcecnc.com/jointcam.html

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  6. #26
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    Re: Interpreting Opinions for Gecko vs Cheap Drivers

    I think many drives have full step morphing as the advantage Gecko may have won here years ago has gone.
    Anti resonance is only an issue if you run the drive at a speed in the resonant frequency range. Just looking at a current design for a stepper application, we are working on full steps anyway, 6283 steps per mm and a resonant frequency of 660 Hz or about 6mm/min. This is a system that can accelerate to 10200 mm/min (400 in/min) in 0.5 seconds so resonance won't really be an issue. If it is in that resonant zone, it won't be there long! But its hardly a system that would be found on a hobby machine due to cost. What will drive us to select a high quality drive is the input voltage required at 100 volts and beyond.
    Rod Webster
    www.vehiclemods.net.au

  7. #27
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    Nov 2013
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    Re: Interpreting Opinions for Gecko vs Cheap Drivers

    Hi,
    steppers like all electric motors produce a back EMF and when decelerating generate electrical energy which is pushed back into the driver.
    You may have seen for instance VFD's and servo drives where you can add a 'braking resistor', the resistor is specifically to allow excess energy
    to be dissipated rather than over-voltage the drive.

    Geckos have a long and well deserved reputation for reliability and much of that is due to the graceful way the drive accommodates the reverse energy.
    The reasons that they can do so is not really a matter of specification but rather carefully selected (and probably expensive) components and design.
    Simply Geckos are good because they have been doing it a while and have gotten real smart about making bullet proof designs.

    Leadshine have also carved out a good reputation, still a little behind Gecko perhaps, but good none-the-less.

    Craig

  8. #28
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    1195

    Re: Interpreting Opinions for Gecko vs Cheap Drivers

    Leadshine have also carved out a good reputation, still a little behind Gecko perhaps, but good none-the-less.
    They have good products hybrid stepper or closed loop stepper, the price is not too expensive. They claim the product is a lot better than stepper. More speed before losing step.

  9. #29
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    Re: Interpreting Opinions for Gecko vs Cheap Drivers

    Hi,

    They claim the product is a lot better than stepper. More speed before losing step.
    Thats what they claim but I think its hype.

    All steppers lose torque the faster they go, that's plain physics and a closed loop does not change that.

    If you want genuine closed loop performance get a servo.

    Craig

  10. #30
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    Re: Interpreting Opinions for Gecko vs Cheap Drivers

    If you want genuine closed loop performance get a servo.
    Good recommendation for next build, cost is not much different today. Wiring is not too complicated. Encoder cable is provided, the rest is almost the same as stepper. The last is just setting by programming.

  11. #31
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    May 2014
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    Re: Interpreting Opinions for Gecko vs Cheap Drivers

    This is all excellent info and I appreciate the detail. Could I ask for a little input in the spirit of the OP? For someone building a DIY "hobbyist" machine, is there a 2020 update on budget drivers that might be acceptable? I totally get the sentiment that the incremental cost of just the drivers is not that much, and that having to then buy the better drivers makes the build even more expensive. However, if this exercise is repeated over all the other components - motors, rails, ball screws, then the cost savings could really add up, and replacing the weakest components based on real world performance could then get one to acceptable overall performance for the application, whereas buying the best of everything would have made the project untenable to begin with. I hope this logic makes sense. Last I saw in this thread, someone was recommending JKD 2060, and I just saw those for $39 online.

    For reference, my CNC build would be for bass guitar and guitar construction, so I need a long but narrow work area 48" x 17" roughly. I know from what I've learned and just from common sense that I can build a stiffer machine if I take advantage of the narrow workspace, assuming that the gantry rails run along the long 48" dimension. I've got a zenbot 2448 at present, and it works reasonably well, but I think I could do better, and then sell the zenbot.

  12. #32
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    Re: Interpreting Opinions for Gecko vs Cheap Drivers

    I've been working with an engineer on that 2020 update for a few weeks now. They are very predictable devices and have been around for over 100 years. His model says we can get amazing results form a given stepper but then something falls outside reality. Like we need 215 volts to feed this stepper acellerating at 1 G. So today I asked him to work on applying constraints so we can see how much performance is lost. We have found there is a significant difference between a cheap stepper and a quality one which is around inertia, reistance and inductance. I think if we've leanrt anything it is that gearbox ratios and pinion diameters are both different tuning parameters and I would not use less than 70 volts (probably 90 volts) on any future project. But then I found my cheap NEMA34's just would not use past 60-70 volts anyway.

    One constraint that we have right now is from our knowledge, we can't find a stepper driver that can handle more than 160 volts 8.5 amps so if you know of any let us know.

    We did postulate that the complexities of stepper design to harness their low down torque probably encouraged the uptake of servo motors.....
    Rod Webster
    www.vehiclemods.net.au

  13. #33
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    Re: Interpreting Opinions for Gecko vs Cheap Drivers

    Hi,

    We did postulate that the complexities of stepper design to harness their low down torque probably encouraged the uptake of servo motors.....
    I'm not sure I agree with your characterisation of steppers there RodW.

    I have recently bought some 750W Delta B2 series servos, and they kick arse!!. They are 2.4Nm continous (7.2Nm 10 sec overload) and rated to
    3000rpm (5000rpm max). They are 34 size and about 150mm long.

    An equivalent 34 size stepper will be something like 8-12Nm.

    For a given size and weight a stepper actually has considerably more holding torque (excluding overload operation) than a servo. As the rotational speed increases
    however these larger steppers lose torque, to sometimes less than 10% at 1000rpm.

    A servo however has constant torque through to its rated speed, so my servos retain 2.4Nm torque at 1000 rpm and retain it still up to 3000rpm.

    Its in the high speed range that a servo really shines, but at low speed steppers actually have more torque. Servos have greater resolution and other
    control features, but as a first approximation, steppers do well, even better than servos at low speed whereas servos wipe the floor at high speed.

    As a matter of practice sevos seem to 'punch above their weight'. The temporary overload of servos would tend to make you think that they are
    more powerful than they are. Steppers on the other hand....if you push them just a few percent over their limit....they stall....no ifs or buts....they stall.

    OP is trying to secure the best possible performance axis motors for his machine at lowest possible cost....no surprises there.......we all are!!!

    Both Leadshine and Gecko have drivers capable of 80VDC, and at the current time that represents the practical voltage limit for stepper drives
    suitable for hobby use. 80VDC will certainlt\y make any stepper take notice but will still sag at speed. To OP....if the loss of torque at speed
    is more than you wish or can tolerate then get servos and be done with it.

    The Delta brand I mentioned are Taiwanese, manufactured in China and are good quality that won't break the bank. For instance my 750W servo/drive
    and cables were $480USD excluding shipping. They are still a considerable step up in price and performance than steppers but the price difference is
    shrinking.

    There are even cheaper no-name brands of AC servos coming out of China but are questionable quality, support and documentation. The prices
    are so compelling that many hobbyists are buyimg them up with good resulkts in the main.

    Craig

  14. #34
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    Re: Interpreting Opinions for Gecko vs Cheap Drivers

    I'm not surprised you don't agree with us becasue a few weeks ago I would not have agreed with myself either! I started by building a plasma machine and using a seat of the pants design based on some stepper drives I had on hand (Longs Motor DM542A which were limited to 50 volts. So I settled on a 48 volt switch mode power supply. The 7 amp one I had was not quite enough so I upgraded to a 10 amp one. The original plan was to use 1.9 Nm NEMA23's all round and I got the X & Z up and running using them. When it came to the dual motor gantry on the Y I found some cool 5:1 belt reducrtions with a pinion cheaper than what it cost to make the X axis reduction. But they needed NEMA 34's so I upgraded to a small NEMA 34 to keep within my power budget and 4 amp stepper drives.. Current price is $55. This was a home build right?

    Don't get me wrong, this was a pretty quick system pulling 21 m/s rapids with a 30 kg gantry. We profiled the acceleration in Linuxcnc's software osciloscope and found we could get to 10,240 mm/min in 2.3 seconds. That was the fastest cutting speed we could find in a Hypertherm manual. I than asked a couple of others to do the same test. One had a 140 kg gantry and 72 volt toroids. He got to speed in 1.9 seconds. Another using nema 23's was pulling 50 m/s rapids with very high quality European drives and his acelleration was the same as mine. His table was still under construciton so maybe he would have increased the acceleration over time.

    By then we had a reaonably complete but mathematically flawed model (Don't believe everything you read on the internet is gospel right?). So now we have a solid model and I wanted to see if I could retrofit my table with the model output as an affordable engineered solution as opposed to a kick arse commercial machine. We wanted to reduce that acceleration to 0.5 seconds. In the end, this was too ambitious so we reduced the velocity target to 6,100 mm/min which was a more reasonable setting as few would cut the thin materials that require 10,240 mm/min. Quite clearly the $55 stepper was out of the league and really did not want to use more than 48 volts at all. So after a few iterations, we found a 5 amp stepper from Moon which got us to 6100 m/s in 0.5 sec at 71 volts ( a 460% performance improvement). But it needed a different pinion diameter and gearbox ratio to what I had. The gearbox ratio can be fixed but its not viable on my machine to change the pinion diameter. The consequence of this is that I would need to feed my motors 139 volts which requires some pretty serious high quality drives. The ones we are looking at can go to 160 volts, 8.5 amps.

    So that brings you up to date with my journey. The next step is for me to decide if I really want to spend $2k or so on what is a perfectly adequate machine or wait for my associate to build a table to the model specs to prove the maths is good. We are certain it has to be.

    So our design won't help the OP as we are optimising for acceleration with no cutting forces but our model can factor those in.
    Rod Webster
    www.vehiclemods.net.au

  15. #35
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    Re: Interpreting Opinions for Gecko vs Cheap Drivers

    Hi,

    So that brings you up to date with my journey. The next step is for me to decide if I really want to spend $2k or so
    The high voltage drives are required to give high speed, always the Achillies heel of steppers. But 2k puts you in servo territory.
    May I suggest you price some Delta's (Taiwanese manufactuered in China) or DMM's (Canadian manufactured in China).
    I have personal experience with Delta's and by my estimate they 'Eat any stepper ever made'.

    Craig

  16. #36
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    Re: Interpreting Opinions for Gecko vs Cheap Drivers

    Quote Originally Posted by joeavaerage View Post
    Hi,



    The high voltage drives are required to give high speed, always the Achillies heel of steppers. But 2k puts you in servo territory.
    May I suggest you price some Delta's (Taiwanese manufactuered in China) or DMM's (Canadian manufactured in China).
    I have personal experience with Delta's and by my estimate they 'Eat any stepper ever made'.

    Craig
    Doing nothing is also a good option too! There is nothing inherently wrong with it and I did wonder how the lightweight gantry would handle the massive increase in inertia!
    A lot of the cost is really becasue I did it wrong at the beginning. It would not be near that on a new machine. 50 volt stepper drives is a constraint as is the power supply sized to suit.
    But from what I can see, the existing drives would not really benefit from added voltage and i doubt I could squeeze a toroid into the control panel. So it becomes power supply, drives, motors, and maybe added gearboxes before you blink.
    Rod Webster
    www.vehiclemods.net.au

  17. #37
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    Re: Interpreting Opinions for Gecko vs Cheap Drivers

    So coming back down to "high end hobbyist machine" for cutting wood, including maple (bass and guitar building), what do you all think of this, which got a favorable mention on this thread?

    https://lynxtoolsandmachinery.com/pr...iver-jkd-2060h

    It would be for driving a NEMA23 motor, probably with 1610 ball screws. It's certainly not expensive, in fact much cheaper here than other references I've found. I seems to have anti-resonance and a lot of the other features mentioned, although I see no mention of stall detection.

  18. #38
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    Re: Interpreting Opinions for Gecko vs Cheap Drivers

    From the specs, its an AC input drive so you feed AC in and get roughly 1.4 x out. So a 60 volt regulated AC toroid would give you about 84 volts out. Be sure to take that into account
    Rod Webster
    www.vehiclemods.net.au

  19. #39
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    Re: Interpreting Opinions for Gecko vs Cheap Drivers

    Didn't it say AC or DC?

  20. #40
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    Re: Interpreting Opinions for Gecko vs Cheap Drivers

    Quote Originally Posted by Jandyman View Post
    Didn't it say AC or DC?
    Yes it does sorry I missed that. But it wil let you use a bare toroid without a dc rectifier whic may be cheaper and eliminates one failure point.
    Rod Webster
    www.vehiclemods.net.au

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