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  1. #1
    Can anyone tell me the difference between the Leadshine easy servo drives on the current Leadshine website (ES-M22430 motor with ES-D808 drive) and the similar spec Leadshine combo I see on eBay (60HS30-EC-1000 motor with HBS86 drive)?

    Leadshine website - http://www.leadshine.com/productdeta...odel=ES-M22430

    eBay - http://www.ebay.com/itm/Leadshine-3N.../191633860794?
    Last edited by Tenson; 12-09-2015 at 06:50 PM.

  2. #2
    I think hey are the same and are not real servo drives as such. It's a stepper motor with closed loop control. Servo motors are usually 3 phase AC driven, or brushed DC motors.

  3. #3
    Any idea why the numbers for the parts are different?

    In terms of electronics a servo is just a closed loop system, i.e. it has negative feedback, so whether the motors are steppers, DC or AC, brushed or brushless the servo is the feedback component of the system.

  4. #4
    Quote Originally Posted by Tenson View Post
    Any idea why the numbers for the parts are different?
    Yes the HBS are the early version of the drive and superceded by the ES-D. Pretty much the same drive just with updated software.

    It's a like the EM806 superceded the AM882 which are basicly same electronics with updated software. Slight improvement in smoothness with the EM compared to AM but nothing to get excited about or a pay lot extra for.
    Similiar with the ES-D over the HBS thou I do think there as been lot more tweaks and some performance gains compared to the AM/EM range.

    The Easy Servo works exactly like a Servo system it just use's a stepper motor so can't spin has fast or has the linear torque like servo motor offers.
    In terms of accurecy then servo's resolution is usually higher with higher count encoders but at this lower level with lower grade ballscrews etc then stepper system if sized and tuned correctly will give them a good close run chase on accurecy.!

    Now let me just say this which may make you look again at why you want this closed loop or any Servo system for that matter.?

    Closed loop just means it will closely follow the path it's be told to follow and if outside of it's set parameters it will fault.
    If it strays from the path slightly the electronics will bring it back on path.! . .. BUT the fact still remains it's lost it's way along the path and the damage is done. It's cutaway material that can't be put back.?
    Yes when it finishes the Job it won't have lost it's starting position and will go back to exactly the same place. BUT still the fact remains it strayed and cut material it shouldn't have so job is wrong.!

    Like saying that's nice straight edge but whats this squigly bit then goes straight again .? Oh the servo got lost for fraction of second but it's ok it remembered where it was and carried on ok.!!! . . . . No the thing is still fubar because it shouldn't have squigle in it.!

    Steppers if sized and tuned correctly are perfectly fine. For larger machines or machines that need rapid movement then servos rule but at lower level then steppers are not far behind servos and IME servos offer nothing other than extra power and slightly smoother if tuned correctly. The Closed loop means nothing really, lost is still lost be that a little or lot still means the job is wrong.
    Last edited by JAZZCNC; 13-09-2015 at 02:12 AM.

  5. #5
    Surely one advantage with closed loop is that if the following error is set to a very small figure, the machine will just stop, and not perform any squiggles, rather than continue after a machining error? G.
    Last edited by GEOFFREY; 13-09-2015 at 09:06 AM.

  6. #6
    Quote Originally Posted by GEOFFREY View Post
    Surely one advantage with closed loop is that if the following error is set to a very small figure, the machine will just stop, and not perform any squiggles, rather than continue after a machining error? G.
    Yes geoffrey that is true upto a point and actually how servos work. Lots people don't realise that a servo never actually is truely on the path but instead is continually off course and making tiny tiny course adjustments TRYING to get back on the path. Obviously these adjustments are so small they are not seen in normal use.
    But if you set the parameters too high then you will be open to faults all the time. It's essentially a balance between accurecy and reliabilty.
    Also it only faults AFTER it's got lost so still some damage is done, yes with high falling error setting you have limited it but still material you didn't want to lose has gone.!

    Now don't get me wrong I'm not saying Servo's are Rubbish or not better than Steppers because they are in several ways. BUT not always in the ways people think and they certainly often put too much focus on the closed loop aspect when in real terms it offers very little over a properly Sized and setup stepper system. Esp at DIY level to Low end industrial use.

  7. #7
    One reason I like the idea of servo steppers is because I find the machine sometimes loose steps when pocketing circles. When it goes to the centre it needs to change direction really fast to keep constant velocity. It then loses position slightly. My current solution is to slow the feed part way through the operation as it nears the centre, but at the moment that means manual g-code edit for me. I might also want to machine a whole sheet of detailed nested parts and then finish off with the through cuts so vacuum is maintained until the final cuts, but doing so much work across the sheet and then eventually coming back to the first part I find I may be out of position very slightly.

  8. #8
    Quote Originally Posted by Tenson View Post
    One reason I like the idea of servo steppers is because I find the machine sometimes loose steps when pocketing circles. When it goes to the centre it needs to change direction really fast to keep constant velocity. It then loses position slightly. My current solution is to slow the feed part way through the operation as it nears the centre, but at the moment that means manual g-code edit for me. I might also want to machine a whole sheet of detailed nested parts and then finish off with the through cuts so vacuum is maintained until the final cuts, but doing so much work across the sheet and then eventually coming back to the first part I find I may be out of position very slightly.
    Well you have under powered steppers or are overtuned if loosing steps or position.(or some mechanical issue) The closed loop system won't help in this case all it will do is fault rather than carry on out of position. Under powered or Overtuned it will be just same closed loop or not and Only way around this is correctly sized steppers or tune motors correctly.

    My machine cuts Ali for 10hrs + with deep DOC at High feeds and still comes exactly back to where it started.
    Like today it did a 4hr job with multiple tool changes and straight after a 2.5hr job with 5 tool changes. The last operation was a Finish pass on some pocket walls with smaller dia tool to clear out the corners etc. If I'd lost just few micro steps this would have shown on the pocket floors. And this was after 6.5hrs straight cutting Ali with at times high feed trochoidal toolpaths with 20mm DOC using 8mm cutter, 15 toolchanges and 200+ drilled holes.

    So what I'm saying is Closed loop won't help a badly setup or under powered machine.! Or make it anymore accurate than a correctly setup plain vanilla stepper machine.
    Last edited by JAZZCNC; 13-09-2015 at 11:03 PM.

  9. #9
    You say it will 'fault' you mean it will just stop? I thought the whole point was it will get back to position and carry on.

    How do you mill circular pockets? Say you want a 30mm pocket and you set a feedrate of 2000mm/min then it will be rather slow at the outside edge but at the center the direction changes will be super fast and the motors can't keep up.
    Last edited by Tenson; 13-09-2015 at 11:26 PM.

  10. #10
    Quote Originally Posted by Tenson View Post
    You say it will 'fault' you mean it will just stop? I thought the whole point was it will get back to position and carry on.
    Yes it will stop if it's outside of it's following error parameter. You are loosing steps for a reason not because steppers are inaccurate. That reason will still be there unless you change something like use larger motors or change the tuning setup. Closed loop system will correct for some error before it reaches the following error threshold but still error happend and if while in the cut material will be lost.!

    In your case with only happening on occasional Rapid moves then Closed loop probably will correct the error rather than fault. But thats an awful expensive route when just buying correct size steppers/drives and/or tuning motors correctly will give you exactly same results.

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