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IndustryArena Forum > CNC Electronics > Servo Motors / Drives > Are Chinese servos a gamble? Servos vs Leadshine closed loop
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  1. #25
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    Re: Are Chinese servos a gamble? Servos vs Leadshine closed loop

    I heard the chinese servos are difficult to tune without proper software (which probably doesn't exist for them in english, yet). This still means they can be tuned though, right?

  2. #26

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    Re: Are Chinese servos a gamble? Servos vs Leadshine closed loop

    Quote Originally Posted by j3dprints View Post
    I heard the chinese servos are difficult to tune without proper software (which probably doesn't exist for them in english, yet). This still means they can be tuned though, right?
    You would have to check that out with the supplier, to see if they have tuning/setup software, any of the good ones will have a PDF manual, and software, don't buy any that you can't get a good English manual with, or can down load before you buy
    Mactec54

  3. #27
    Community Moderator Al_The_Man's Avatar
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    Re: Are Chinese servos a gamble? Servos vs Leadshine closed loop

    Quote Originally Posted by RCaffin View Post
    I have seen 110VAC, 115 VAC, 120 VAC quoted for America, and even 220 VAC and 240 VAC in some places.
    Yeah, and oddly enough they use 120/240 in Richmond BC, where I believe DMM is situated. That's in Canada!
    N.A. in general has settled on 120/240 as a standard, you may still see appliances marked 110vac which is the old standard.
    It is normal for a power grid service to fluctuate and generally the accepted industrial standard for fluctuation for industrial machinery is ±10%.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  4. #28
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    Re: Are Chinese servos a gamble? Servos vs Leadshine closed loop

    This would make a great HM47/RM45 mill spindle motor if it does what they say it does

    https://www.ebay.com.au/itm/7-7NM-2K...MAAOSwxixZ5w~L

    Free shipping to Australia, 649.90 AUD similar price range to a class F 2.2kw motor and VFD. This provides approximately the same torque (at max RPM) but weighs 10kgs compared to 21,
    a big advantage when the z axis must deal with the mass of the motor. Might be a good way to test the quality of these servos where position control is not essential.
    I sent them a message asking for the manual, will post on here if they send me one.

    Ed
    Perth

  5. #29
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    Re: Are Chinese servos a gamble? Servos vs Leadshine closed loop

    They got back to me in about 5 minutes.

    https://1drv.ms/b/s!ArjCcDfiJFt0fm4tmJyHfblBVm0

  6. #30
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    Re: Are Chinese servos a gamble? Servos vs Leadshine closed loop

    They do indeed seem good. You can get them for 600 shipped.

    Is 2500 ppr really a big deal on these servos?

    Also servos outperform a leadshine in every respect, really? I am not after super fast rapids, I would like Tormach potential which boast under 150ipm for their ipm speeds on their mills and good ACCURACY. I am aware they use open loop with torque reserve and good engineering to not miss steps. With leadshine closed loop steppers I could achieve no missed steps and similar IPM / accuracy I think. Or with their clones. I have read steppers if they don't miss steps can actually be more accurate than servos (in my price range).

    Prices for Aussie customers and pros/cons I've noted are as follows:
    Leadshine CLONE CLOSED LOOP steppers for like $700 AUD delivered (clones so.... not as great drivers?)

    Leadshine closed loop genuine (chinese models) are more like $900 (steppers, not servos, but is this really a disadvantage if you're not chasing massive IPM)

    Chinese Servos come in at 1000 to 1200 (good but 2500ppr, and bad manuals),

    Chinese servos with better encoders - around 1500-1600

    DMM for just under $2000 delivered to Aus.

    I am really really looking toward option 1 - leadshine clones. Save 1400 over DMM. I reckon they will equal whatever Tormach has and the money I'll save will be better spent on other things - better ballscrews later, hiwin rails for x and y, A nice surface table, or even money off a Skyfire / Tormach / VMC which I might upgrade too later.

  7. #31
    Community Moderator Al_The_Man's Avatar
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    Re: Are Chinese servos a gamble? Servos vs Leadshine closed loop

    Quote Originally Posted by j3dprints View Post

    Is 2500 ppr really a big deal on these servos?
    .
    Keep in mind that that is the basic quadrature count, most controllers will times this by 4 by counting all four edges.
    Resulting in 10k pulses/rev in this case.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  8. #32

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    Re: Are Chinese servos a gamble? Servos vs Leadshine closed loop

    Quote Originally Posted by edmunns View Post
    They got back to me in about 5 minutes.

    https://1drv.ms/b/s!ArjCcDfiJFt0fm4tmJyHfblBVm0
    These servo motors are OK but there servo drives users have had problems with them, I would not touch that brand
    Mactec54

  9. #33

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    Re: Are Chinese servos a gamble? Servos vs Leadshine closed loop

    Quote Originally Posted by j3dprints View Post
    They do indeed seem good. You can get them for 600 shipped.

    Is 2500 ppr really a big deal on these servos?

    Also servos outperform a leadshine in every respect, really? I am not after super fast rapids, I would like Tormach potential which boast under 150ipm for their ipm speeds on their mills and good ACCURACY. I am aware they use open loop with torque reserve and good engineering to not miss steps. With leadshine closed loop steppers I could achieve no missed steps and similar IPM / accuracy I think. Or with their clones. I have read steppers if they don't miss steps can actually be more accurate than servos (in my price range).

    Prices for Aussie customers and pros/cons I've noted are as follows:
    Leadshine CLONE CLOSED LOOP steppers for like $700 AUD delivered (clones so.... not as great drivers?)

    Leadshine closed loop genuine (chinese models) are more like $900 (steppers, not servos, but is this really a disadvantage if you're not chasing massive IPM)

    Chinese Servos come in at 1000 to 1200 (good but 2500ppr, and bad manuals),

    Chinese servos with better encoders - around 1500-1600

    DMM for just under $2000 delivered to Aus.

    I am really really looking toward option 1 - leadshine clones. Save 1400 over DMM. I reckon they will equal whatever Tormach has and the money I'll save will be better spent on other things - better ballscrews later, hiwin rails for x and y, A nice surface table, or even money off a Skyfire / Tormach / VMC which I might upgrade too later.
    You heard wrong they could never be as accurate as AC Servos, even the cheap ones, when you have to chase your dollars as I said before buy what you can afford, but don't get the servos that Edmunns just listed, if these where the ones you looked at

    It looks like the genuine Leadshine is your best bet , with there encoders at,2500=10,000ppr if they are incremental, yes Encoders are a big deal, these servo's are not worth the extra money to buy them, the Dmm Encoder is 65,384ppr standard
    Mactec54

  10. #34
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    Re: Are Chinese servos a gamble? Servos vs Leadshine closed loop

    Yeah, I wasn't suggesting to go down that path, you get what you pay for, especially with servos. That manual looks like a nightmare haha.

  11. #35
    Community Moderator Al_The_Man's Avatar
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    Re: Are Chinese servos a gamble? Servos vs Leadshine closed loop

    With encoder resolution, you can calculate your Least Input Increment, this is the smallest value the machine can position to.
    For example, if the quadrature encoders are 2500 = 10,000 pulses/rev when x4, and you have a motor driving a 0.2" lead Ball screw direct, then the Least Input Increment = 0.2"/10k =0.00002", or 0.5 Micrometer.
    To go much smaller L.I.I. with any accuracy would also require very precise machine mechanics.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  12. #36
    Community Moderator ger21's Avatar
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    Re: Are Chinese servos a gamble? Servos vs Leadshine closed loop

    With leadshine closed loop steppers I could achieve no missed steps and similar IPM / accuracy I think.
    There is really no comparison between closed loop steppers and servos. Look at a torque curve for a closed loop stepper. At 1000 rpm, it will have lost at least half of it's rated torque. A servo will have full torque up to 3000rpm, with 3x peak torque still in reserve.

    When used properly, an open loop stepper should give nearly identical performance to a closed loop stepper. They are both steppers, after all, with the same amount of power.
    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)

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