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  1. #1
    Hi Guys

    I decided I wanted to upgrade my nema 23 425 motors to nema 34's. Figuring it would be a simple job I went about ordering new motors and fitted them today. However since fitting them it's taken my machine out of action.

    I have leadshine dm856 drivers hooked up to 48v power suppliers. Prior to the switch I was able to jog at 8000mm a min easily enough. Now I can't go past 500 without jamming. Acceleration is set to 50... steps haven't changed and it's a 1605 ball screw machine.

    These are the new motors:

    https://www.ebay.co.uk/itm/DE-Ship-4...keFS:rk:1:pf:0

    I feel like I'm missing something, but I'm not sure what...

    I have just a single motor connected to X at present...

    If I jog it just seems to jam up

  2. #2
    m_c's Avatar
    Lives in East Lothian, United Kingdom. Current Activity: Viewing Forum Superstar, has done so much to help others, they deserve a medal. Has been a member for 9-10 years. Has a total post count of 2,391. Received thanks 266 times, giving thanks to others 6 times.
    Bigger isn't always better.

    To get the best out of those Nema 34 motors, you'd need a 150V power supply.
    There are very few applications where Nema 34 are better suited than Nema 23/4, as unless you need the maximum amount of torque with limited speed, good Nema 23/4 motors will perform far better.
    Avoiding the rubbish customer service from AluminiumWarehouse since July '13.

  3. #3
    Nuts.... I thought that might be the case as everything I'm aware of points to underpowered... I can't work out why these are sold with 60v supplies?

  4. #4
    m_c's Avatar
    Lives in East Lothian, United Kingdom. Current Activity: Viewing Forum Superstar, has done so much to help others, they deserve a medal. Has been a member for 9-10 years. Has a total post count of 2,391. Received thanks 266 times, giving thanks to others 6 times.
    Quote Originally Posted by Mr*Beaver View Post
    I can't work out why these are sold with 60v supplies?
    For people who do no proper research and automatically assume bigger is better.

    If you really want to improve performance, you want the lowest inductance motors possible, as inductance is what results in back emf and is what really limits how fast you can get motors to run under comparable conditions.
    But even with high voltage stepper drivers and Nema 34s, it's very likely a Nema 23/4 with a suitable supply will produce more useable performance.
    Avoiding the rubbish customer service from AluminiumWarehouse since July '13.

  5. #5
    Unfortunately yes you have fallen into the Nema34 trap. It is a common question on here asking if more performance can be obtained from Nema34 steppers instead of 23. The answer is only if the voltage is high and often mains powered stepper drivers are recommended. This can make sense on a dual ballscrew axis off a single Nema34, but otherwise they are more suited to say a big mill conversion.

    Where does this leave you? Well your drivers are rated at 80V max so may be run at 70V nominal which is not enough of a step up over 48V on the motors so you are it bit stuck.

    Will these motors make a future upgrade on some heavy bit of manual machinery you might have? Otherwise maybe return or sell on and fit a 70V dc power supply instead of 48V and revert back to 23s. This will give a bit more performance over the original setup.

    Sorry that we’ve had to spoil your Christmas 🎄
    Building a CNC machine to make a better one since 2010 . . .
    MK1 (1st photo), MK2, MK3, MK4

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  7. #6
    Quote Originally Posted by routercnc View Post
    Unfortunately yes you have fallen into the Nema34 trap. It is a common question on here asking if more performance can be obtained from Nema34 steppers instead of 23. The answer is only if the voltage is high and often mains powered stepper drivers are recommended. This can make sense on a dual ballscrew axis off a single Nema34, but otherwise they are more suited to say a big mill conversion.

    Where does this leave you? Well your drivers are rated at 80V max so may be run at 70V nominal which is not enough of a step up over 48V on the motors so you are it bit stuck.

    Will these motors make a future upgrade on some heavy bit of manual machinery you might have? Otherwise maybe return or sell on and fit a 70V dc power supply instead of 48V and revert back to 23s. This will give a bit more performance over the original setup.

    Sorry that we’ve had to spoil your Christmas ��
    Ah well, I thought it was a little too easy.

    Thanks for the info, very much appreciated.

    Now time to re-wire the old ones back up and order some new couplers - teaches me to change my ball screws at the same time... :)

  8. #7
    Quote Originally Posted by m_c View Post
    Bigger isn't always better.

    To get the best out of those Nema 34 motors, you'd need a 150V power supply.
    There are very few applications where Nema 34 are better suited than Nema 23/4, as unless you need the maximum amount of torque with limited speed, good Nema 23/4 motors will perform far better.

    Yes, bigger one is not always better.

  9. I had one for my Z axis and literally through it in the bin. I got suckered too.
    The inductance is shocking.
    Got an 8 wire 1080oz nema 34 now. Massive difference.

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