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  1. #151
    Neale's Avatar
    Lives in Plymouth, United Kingdom. Last Activity: 15 Hours Ago Has been a member for 5-6 years. Has a total post count of 1,162. Received thanks 209 times, giving thanks to others 5 times.
    I don't know if anyone has done a controlled side-by-side comparison of the AM882 and the EM806. I bought the EM drives for my machine as I was fed up with buying things that seemed to go obsolete almost as soon as they were delivered and the EM series was still fairly new on the street, with supposedly better anti-resonance algorithms, etc. That was around 3 years ago but the AM drives are still going strong! However, I can say that I am very happy with my EM drives - no resonances ever been apparent, and the anti-stall is very useful if for some reason the gantry has gone out of square and loads get too high on rapid feed. Machine stops quickly without tearing itself apart. Would the AM drives have worked as well? Dunno!

    One day I'll make up a serial cable and try to set up the autotune properly. Still slightly confused about how that's supposed to work with a dual-motor setup as you clearly can't do it with the motors connected to the ballscrews, but it doesn't seem to make sense to try to tune the motors when they're unloaded.

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  3. #152
    I have an Am and two EM's on my milling machine and I can't see much of a difference to be honest.

    However, for my new router I am using four EM's. As you say, Neale, the stall function really works, I had my milling machine travel out of bounds without a limit switch and as soon as it hit the end, the driver stopped it preventing any damage. Also good for when you make a mistake and go too severe with your cut, it soon stalls the movement and prevents further damage.

    My thought is, if you can afford it, buy EM's from Zapp, they are actually quite reasonably priced and it's just a one off expense anyway and it supports a UK firm. If you really are on a very tight budget, buy AM's from China, but expect customs duty, some wait and at the end of the day, you are not saving much more than a round of beers, if that.
    Last edited by Edward; 31-12-2017 at 12:29 PM.

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  5. #153
    Quote Originally Posted by Neale View Post
    I don't know if anyone has done a controlled side-by-side comparison of the AM882 and the EM806. I bought the EM drives for my machine as I was fed up with buying things that seemed to go obsolete almost as soon as they were delivered and the EM series was still fairly new on the street, with supposedly better anti-resonance algorithms, etc. That was around 3 years ago but the AM drives are still going strong! However, I can say that I am very happy with my EM drives - no resonances ever been apparent, and the anti-stall is very useful if for some reason the gantry has gone out of square and loads get too high on rapid feed. Machine stops quickly without tearing itself apart. Would the AM drives have worked as well? Dunno!

    One day I'll make up a serial cable and try to set up the autotune properly. Still slightly confused about how that's supposed to work with a dual-motor setup as you clearly can't do it with the motors connected to the ballscrews, but it doesn't seem to make sense to try to tune the motors when they're unloaded.
    That's what we need is a side by side comparison, when I build my next router I might go with EM806's (Although planning the easy servo drives with matching motors) just to compare with same toroidal PSU setup. They are plug compatible so could relatively easy swap them over just for testing.

    They don't sell EM806's on alixpress and the suppliers I contacted said they don't sell them in Asia they are only sold in US and Europe but I always take what suppliers say with a pinch of salt lol.

    On the clone issue I think it's how good a clone is it? If the clone performs and works exactly the same then the issue is slight, if it's a poor clone then problems occur.

    I have no idea if my AM's are clones but the internals look identical when I stripped them down and they all seem to perform the same. Almost silent performance if I set the microsteps to 32.

    https://www.youtube.com/watch?v=O4_u5ov-9cc

    I'm going to set them to 8 for now which makes them sound like normal whiney steppers but more torque of course.
    Last edited by Desertboy; 31-12-2017 at 12:41 PM.
    http://www.mycncuk.com/threads/10880...60cm-work-area My first CNC build WIP 120cm*80cm

    If you didn't buy it from China the company you bought it from did ;)

  6. #154
    Customs duty is fickle but split your purchases and send to friends to eliminate them for stuff like this. I paid £15 on my first 2 and nothing on the next 3 and the one that was faulty I probably blew up as I also blew up a toroidal transformer so that's down to me being crap lol.

    I can understand what your saying but you can buy 4 New AM882's for £240 delivered vs £440 for the EM806's that's quite a few rounds of beers in Leicester lol. If I was on a budget it's here I'd save my £200 to spend elsewhere say on PSU or upgrade the ballscrews/Hiwin sizes.

    The limit is £40 from China I've found split the deliveries and anything under £100 you don't get charged. I spent less than £70 on tax on my router build and over £1200 from China and most my tax was the ballscrews.

    I think the £200 buys you a replacement EM806 if one goes wrong which is a good warranty for me ;)

    I too have crashed 2 out of 3 axis on my router and stall protection kicked straight in ;) so if I have clones I have working clones.

    There is after all 2 ways to clone this drive
    1. Make an exact clone with same chips or equiv and use the same firmware, done right the difference between the original and clone is minimal and sometimes clones are actually better.
    2. Put a cheap driver in a copy AM882 box and the stall protection ports are not connected to anything lol. Hack the firmware so the dip switches make sense.
    Last edited by Desertboy; 31-12-2017 at 01:19 PM.
    http://www.mycncuk.com/threads/10880...60cm-work-area My first CNC build WIP 120cm*80cm

    If you didn't buy it from China the company you bought it from did ;)

  7. #155
    This machine is crying out loud for servos. That's my opinion.
    project 1 , 2, Dust Shoe ...

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  9. #156
    Quote Originally Posted by Boyan Silyavski View Post
    This machine is crying out loud for servos. That's my opinion.
    What's your opinion on
    http://www.leadshineusa.com/productt...y-servo-motors

    If I understand it these are not real servos but somewhere in between
    Last edited by Desertboy; 31-12-2017 at 01:45 PM.
    http://www.mycncuk.com/threads/10880...60cm-work-area My first CNC build WIP 120cm*80cm

    If you didn't buy it from China the company you bought it from did ;)

  10. #157
    Quote Originally Posted by Desertboy View Post
    What's your opinion on
    http://www.leadshineusa.com/productt...y-servo-motors

    If I understand it these are not real servos but somewhere in between
    I decided long ago - No to closed loop steppers. Too close to real servos price. 750w servos from BST will much better. Mine machine is all over 400W Samsung servos and i could not be more than happy with them. I doubt this machine will be heavier or much different than mine anyway. If i have to repeat, i will go the same way, like new used second hand brand servos from reputable seller, together with cables and so. If i am making the machine for a client, then new 750w chinese servos. But that's me.

    PS. Just as a side note, brand servos like mine and the panasonic will spin to 6k rpm happily, as opposed to cheap servos. So actually you will never use them at 100%.
    Last edited by Boyan Silyavski; 31-12-2017 at 02:06 PM.
    project 1 , 2, Dust Shoe ...

  11. #158
    Cant decide what i will need until i finish my gantry design and report back as the way i am going like boyan said is i may need servos which i was trying to avoid, what price range am i looking at per axis setup for servos? the hiwin rails and ball screws are whats taking up a lot but i am in no rush

    edit.. just going to point out just in case someone can rescue me from over designing which eventually is going to push me to servos lol, the only thing i will be cutting is wood or up to 10mm acrylic and thats it but it does need to be a solid gantry for 3d carving. i will however want to make a small machine to mill aluminium and steel eventually :)
    Last edited by reefy86; 31-12-2017 at 05:25 PM.

  12. #159
    can you mix steppers and servos? was thinking off having just servos on the long axis that moves the gantry

  13. #160
    Quote Originally Posted by reefy86 View Post
    can you mix steppers and servos? was thinking off having just servos on the long axis that moves the gantry
    In linuxcnc seems easy enough

    https://forum.linuxcnc.org/10-advanc...stepper-system

    Not sure about Mach 3 but if I'm going servo go all the way all 3 axis ;)

    If you're using standard ballscrew at the lengths you want you'll probably see screw whip with normal steppers never mind servos so you might need rotating ballnuts or R&P to see proper performance from servos.

    Google screw whip calculator to get a good idea of what a normal ballscrew can do but it's nowhere near 6k rpm Boyan quoted that servos will do.
    Last edited by Desertboy; 31-12-2017 at 05:45 PM.
    http://www.mycncuk.com/threads/10880...60cm-work-area My first CNC build WIP 120cm*80cm

    If you didn't buy it from China the company you bought it from did ;)

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