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  1. #21
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    BanduraMaker: It would be nice to see a volt and amp reading from your motors to see if the gecko does some magic!



  2. #22
    Member BanduraMaker's Avatar
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    No need, the magic are a few things that's on their website. have no idea how much each influences the performance but they claim that their drives use microsteping, midband resonance damping and "morphing" to get better performance out of the motors and what can I say? It works.

    You can ask anyone on this website that has used more basic drivers that resonance can be a serious problem with stepper stalling at mid to low RPM. Adding dampers to the shaft of the motors can fix it and apparently there's DSP tricks one can do to get rid of it too.

    You may have heard people say before that "according to physics, bumble bees can't fly"? Well, that's absolutely not true. According to physics bumble bees absolutely can fly it's just that elementary physical models don't accurately reflect what's going on to get the damn thing to fly. When the model gets more sophisticated, it more accurately shows how the bee is flying.

    Seeing as my machine runs at 400ipm on the big axis, and I regularly cut at 400ipm, I'm going to say "my bumble bee flies". If the calculator on that site doesn't match my performance it's down to a couple things - either we're entering the parameters incorrectly or the calculator is just plain wrong. I guess to be more kind one could say as I mentioned before, that the calculator is conservative rather than just plain wrong.

    Gecko Drives may not be the best stuff out there but there's a reason they have a good reputation and are recommended on this site. While it's not the solution for every machine, the G540 gives you great performance bang for your buck when it fits the bill.

    -Andy B.
    http://www.birkonium.com CNC for Luthiers and Industry http://banduramaker.blogspot.com


  3. #23
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    Ok.. i found a comment which might explain it... Digital drives can swith between coil states quicker because amps need not to be constant, because of this higher speed is achievable when full torque is not needed also optimized by stall detection.

    These facts have made me consider the Leadshine EM705 combined with 57hs22 LeadShine steppers. This leaves room for a nema 34 upgrade eventually (if i need better acceleration during 3d printing).

    Sent from my GT-I9505 using Tapatalk

    Still Learning..... :D


  4. #24
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    microsteping, midband resonance damping and "morphing" should all be factors limiting the steppers performance from calculated max. Calculator is based on the time it takes to fully charge and then discharge the coil to produce one step. Max voltage in 32xsqrt(Inductance) is only the voltage at which a stepper will produce lots of heat in the motor with very little performance gain. Depending on the torque curve it is quite easy to see that adding voltage above this value is just plain stupid. Exceeding it is not a catastrophe in small ammounts but every volt above is more or less translated into heat. Having a result of 48v from the formula says it will be ok to power at 50v but the additional volts will do little or no gain in performance, 60v vould be really bad as biggest part would be translated into heat (for example 6Amp motor would lead to between 8 and 12v multiplied with 6A equals 48 to 72 Watts of heating.

    The only thing i can see that might affect speed beyond theoretical values is not fully loading the coil to faster be able to switch state. Now this math is beyond me..



  5. #25
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    Last edited by Bx3mE; 12-27-2013 at 07:41 PM.


  6. #26
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    How much do i need to worry about back EMF?

    I plan to use Leadshine 4xEM705, 4x57hs22 steppers, and 2x500W 42V 12A Switching Power Supply with Current Control Charger LED CCTV UDX | eBay



  7. #27
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    Quote Originally Posted by Bx3mE View Post
    How much do i need to worry about back EMF?

    I plan to use Leadshine 4xEM705, 4x57hs22 steppers, and 2x500W 42V 12A Switching Power Supply with Current Control Charger LED CCTV UDX | eBay
    i would not use switching power supply, best to use toroidal transformer Select electronics for my raptorxz-ps-8n70rxx-jpg

    XZero cnc


  8. #28
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    Quote Originally Posted by Bx3mE View Post
    How much do i need to worry about back EMF?

    I plan to use Leadshine 4xEM705, 4x57hs22 steppers, and 2x500W 42V 12A Switching Power Supply with Current Control Charger LED CCTV UDX | eBay
    Also drivers being 70v drivers, i would get a 70v power supply. 42v is to low.

    XZero cnc


  9. #29
    Member gio666's Avatar
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    If wanting to use switching power supply, you could use 2x36v and use this card. Power Supplies | Protoplant

    I have seen to many switching power supply blow up and takes drivers with it

    XZero cnc


  10. #30
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    Quote Originally Posted by gio666 View Post
    Also drivers being 70v drivers, i would get a 70v power supply. 42v is to low.
    Are you sure about this?
    Steppers are 1.8mH so supplying with more than 43v would only generate heat on the stepper... 32*sqrt(1.8) = 42.93 or another formula 1000*sqrt(0.0018) = 42.4

    Leadshine specification is:
    Input Voltage: Min 20 - Typical 48 - Max 70 VDC

    So running this combo on 42v seems optimal... or did i get something wrong?

    As I am typing and rechecking my facts Gecko also states another formula: Vrated*25...
    If you read through the doc it sounds as if they mean whichever is hit first but maybe Vrated*25 is more applicable when wireing half coil?
    If the above is true that would mean i could run the motor at 69,5v which would make sense when refering to the torque/speed curve on Leadshines site.
    They run it at 48v which i can undertstand is at "pushing it" level for optimal 42v wired bipolar-paralell but it is also displayed at halfcoil 68v.

    Maybe I am finally getting a grip on things

    So the hunt for a toroidal transformer at 65-70v and back EMF Clamp begins...

    For reference this Calc Might come in handy if recalculation of values for halfcoil is nessesary (or vice vera)
    Conversion Calculator-Leadshine Technology Co., Ltd.



  11. #31
    Member ger21's Avatar
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    Many years ago, people used the 10-20x rule with 25x max voltage.

    A few years ago, Gecko came out with the 32x inductance formula. I believe that supersedes any references to 25x on their website, as that info has been there for many, many years.

    Personally, I wouldn't run those motors at more than 48V, unless you run them at 48V first and determine that they don't get very hot.

    Gerry

    UCCNC 2017 Screenset
    [URL]http://www.thecncwoodworker.com/2017.html[/URL]

    Mach3 2010 Screenset
    [URL]http://www.thecncwoodworker.com/2010.html[/URL]

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

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


  12. #32
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    Ger21: What is your opinion on the combo (em705 and 57hs22) if run at 42v?

    Link steppers
    Link Driver AND torque curve of the mentioned stepper on p.22

    Can voltage be limited int the driver?

    Last edited by Bx3mE; 12-28-2013 at 07:58 PM.


  13. #33
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    It seams that however i twist and turn i end up in the calculator computing numbers which tend to max out at 12.8rev/sec or 768 RPM on the motor. Doubling that to get the 600IPM i am after just seems impossible. only other option is to go for a 20mm lead ballscrew which is not an option as i want to keep precision.

    The only option is to crank up the voltage and put some ridiculous heatpipes on the steppers which does not seem like a durable option.

    If there is an option to get an motor RPM of 1500 RPM I will go for it. I know people love the geckos but the em series look really good. The DM Series from Leadshine are often referred to as "china quality" based on DQ542MA and the DM556A being from the same production line and people are often advised to go for geckos instead. Does the same apply for the EM Series? Is the "Advanced DSP Technology" just lots of gimmicky control stuff on top of a crappy driver or does it make a difference?

    Option 1:
    EM705 or EM805 kombined with 57hs22 steppers (HalfCoil) (16.4RPS in Calculator = 984 RPM @ 42v and 1.8mH)

    Option 2:
    Gecko G540
    KL23H2100-35-4B (12.8 RPS in calculator = 768RPM @ 50v)

    Option 3:
    Gecko G203V
    keiling KL23H276-30-8B (Half Coil) (17.8 RPS in calculator = 1068RPM @46v and 2.2mH)

    Option 4:
    Another combo of the above

    Which option would you go for?

    Last edited by Bx3mE; 12-29-2013 at 10:32 AM.


  14. #34
    Member ger21's Avatar
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    Quote Originally Posted by Bx3mE View Post
    Ger21: What is your opinion on the combo (em705 and 57hs22) if run at 42v?
    Honestly, unless you have personal hands on experience with a specific motor and drive combination, it's really just a guess.
    Hundreds if not thousands of people are using the G540 - 380oz motor combo and are getting similar results to Andy. It's a proven combination that works.


    Quote Originally Posted by Bx3mE View Post
    Can voltage be limited int the driver?
    Typically, no, unless you use a drive with an integral power supply. And even then I'm not sure if you can.

    As I said before, you're not going to get 600ipm with steppers and 10mm pitch screws. You're best chance of getting close would be 450oz Nema 34's rated at 6 or 7 amps, and run on high voltages.
    Going to a 20mm pitch screw will require twice the torque, as the mechanical advantage is cut in half. You also cut your resolution in half.
    If you want high speeds (over 450ipm) and good resolution, you really need to go with servos.

    Personally, I don't have much faith that the formulas you're using are giving you actual real world results. If you're not factoring in mass and acceleration rates, than the numbers are meaningless imo.

    Gerry

    UCCNC 2017 Screenset
    [URL]http://www.thecncwoodworker.com/2017.html[/URL]

    Mach3 2010 Screenset
    [URL]http://www.thecncwoodworker.com/2010.html[/URL]

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

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


  15. #35
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    Ger21:
    The calculation for me is the only thing i can use as a tool before buying in combination with the words from more experienced cnc:ers like yourself. I dont take the calcs for facts but as a guidline where i expect maybe 50-70% of the performance. If the calc says 50RPM I know it is not for me but if numbers are in the region of 500-1500 and inductance is low i know its worth considering.

    If it were you given the desire for speed would you aim for G540 or 203V?

    Still Learning..... :D


  16. #36
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    Quote Originally Posted by Bx3mE View Post

    If it were you given the desire for speed would you aim for G540 or 203V?
    Depends on the motor. If the motor is rated at 3.5 amps or less, and you'll be running it at 48V or less, then there's no advantage to the G203V.

    Gerry

    UCCNC 2017 Screenset
    [URL]http://www.thecncwoodworker.com/2017.html[/URL]

    Mach3 2010 Screenset
    [URL]http://www.thecncwoodworker.com/2010.html[/URL]

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

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


  17. #37
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    So people are being really happy with the standard setup and i am close to fall to the temptation to go the same route. g540 + 380oz-in 2.8mH + toroidal psu + smoothstepper Eth. I expect to upgrade my setup within a year or so so i will add that little extra $ on the drivers and have the G203V:s. Also these drivers have, according to gecko when comparing G250 from g540 with G203V more tolerant to overvoltage/overcurrent/back EMF etc.

    Cnc routerparts list a ´new´ addition to their line: Its the 320 oz-in which they state being better at holding torque at higher speeds than the 380oz-in. Looking at the specs it seems to be the 57BYGH633 - same as Wantai and others. Given that they have not published any torque curve they made them selves I will skip on this as i have received the specs for this from Wantai and several others stating everything between 1.2 to 22mH Inductance. If CNCRouterparts show a Torque curve they measure themselves i might be interested, until then I am not. Which leaves the 381oz-in 3.5A (KL23H2100-35-4B). So my list so far: (I hope i dont change my mind again )

    3x KL23H2100-35-4B
    3x Gecko G203V
    1x Ethernet SmoothStepper with Terminals
    1x C10 Bidirectional Breakout Board (to connect NEMA17 from BULLDOG Extruder via DRV8825 Driver and Arduino HeatNossle and bed with temp monitor
    1x Unregulated Linear 1120W, Max 56VDC/20A Toroidal PSU (KL-5620) with 5V/1A

    Total is about $1k.


    Optimal Voltage for steppers = 53v (2.8mH).
    PSU drops to <53v with not so much load.

    Comments?

    Still Learning..... :D


  18. #38
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    Hi, Bx3mE.

    My setup:
    USB Breakout Board AKZ250
    Ball screws: 2510-1610 and 1605 (Z).
    Microstep Driver 4,2A with setting: 1/16 and 2,84A (Peak)
    Stepper motor 381oz-in (KL23H2100-35-4B)
    Power supply: 48VDC (@49vdc) - 8.3A

    Its maximum speed is greater than 400IPM:



    The ideal current for 3 stepper motors: 3,5x3x75%: 7.87A
    The ideal current for 4 stepper motors: 3,5x4x75%: 10.50A



  19. #39
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    jassaf: Thanks for sharing! This gives me a lot more confidence in the steppers... When running a job @ 300+ IPM (Constant movements for 20+ minutes - How hot are your motors running?

    I am thinking of using a 56v Toroidal PSU which drops below 53v @ 3+ AMPs...

    Still Learning..... :D


  20. #40
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    Some thinking about the Controller box:

    pmdx MOTOR CABLE CONNECTOR 4 pin
    pmdx Spindle Control pmdx-107
    pmdx display pmdx-179
    pmdx bob pmdx-126
    pmdx gecko motherboard pmdx-134
    PMDX-EStop-Std

    This seems to be a nice complete kit to make a compact yet efficient solution. It should allow for a lot of expansion and be reliable to.

    Still Learning..... :D


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Select electronics for my raptorxz

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