Which Stepper Would Be A Better Buy?


Results 1 to 14 of 14

Thread: Which Stepper Would Be A Better Buy?

  1. #1


  2. #2
    Member awerby's Avatar
    Join Date
    Apr 2004
    Posts
    5728
    Downloads
    0
    Uploads
    0

    Default Re: Which Stepper Would Be A Better Buy?

    From the information provided, I'd say the second one. The first and last don't mention the inductance, and the third has inductance that's too high. With an 80vdc power supply, the second one, with 6.3 mH inductance, would run about as well as could be expected, while the driver would be at its max rating but hopefully wouldn't blow up.

    [FONT=Verdana]Andrew Werby[/FONT]
    [URL="http://www.computersculpture.com/"]Website[/URL]


  3. #3
    Member
    Join Date
    Jan 2012
    Location
    usa
    Posts
    163
    Downloads
    0
    Uploads
    0

    Default Re: Which Stepper Would Be A Better Buy?

    Quote Originally Posted by awerby View Post
    From the information provided, I'd say the second one. The first and last don't mention the inductance, and the third has inductance that's too high. With an 80vdc power supply, the second one, with 6.3 mH inductance, would run about as well as could be expected, while the driver would be at its max rating but hopefully wouldn't blow up.
    i forgot to mention i have a 60v power supply i would like to use, what is Inductance? blow up?
    I think the first one *Inductance: 4.2 mH ± 20%(1KHz)

    Last edited by rmachinist; 02-23-2020 at 08:14 PM.


  4. #4
    Member
    Join Date
    Nov 2013
    Posts
    4280
    Downloads
    0
    Uploads
    0

    Default Re: Which Stepper Would Be A Better Buy?

    Hi,
    absolutely the one with the lowest inductance, 4mH is still too high in my book.

    Why are you fiddling around with a low voltage (60VDC) power supply?. In order to make these steppers go fast you need the HIGHEST voltage the drivers
    will handle.

    Craig



  5. #5
    Member
    Join Date
    Jan 2012
    Location
    usa
    Posts
    163
    Downloads
    0
    Uploads
    0

    Default Re: Which Stepper Would Be A Better Buy?

    Quote Originally Posted by joeavaerage View Post
    Hi,
    absolutely the one with the lowest inductance, 4mH is still too high in my book.

    Why are you fiddling around with a low voltage (60VDC) power supply?. In order to make these steppers go fast you need the HIGHEST voltage the drivers
    will handle.

    Craig
    I have a extra brand new 60 volt power supply laying around I thought I can use it



  6. #6
    Member
    Join Date
    Nov 2013
    Posts
    4280
    Downloads
    0
    Uploads
    0

    Default Re: Which Stepper Would Be A Better Buy?

    Hi,
    by all means use it but be aware that an 80V supply will allow the steppers to go 33% faster (before losing steps) than a 60V supply.

    By the way just because its 'closed loop' does not make the motors faster or more powerful. Closing the control loop DOES NOT change the
    physics of steppers.

    Craig



  7. #7
    Member
    Join Date
    Jan 2012
    Location
    usa
    Posts
    163
    Downloads
    0
    Uploads
    0

    Default Re: Which Stepper Would Be A Better Buy?

    33% more that's good jump/ looking around a bit it seems like bigger the stepper higher the inductance



  8. #8
    Member
    Join Date
    Nov 2013
    Posts
    4280
    Downloads
    0
    Uploads
    0

    Default Re: Which Stepper Would Be A Better Buy?

    Hi,
    looking around a bit it seems like bigger the stepper higher the inductance
    Correct. Physics says that bigger motors require bigger coils which enclose more transformer iron ergo higher inductance.
    Thats why sometimes a smaller, apparently lower spec motor, that is lower holding torque, actually outperforms larger motors by virtue of lower
    inductance. Poor performance at high rotational speeds has and will always be-devil stepper motors. If you want genuine high rotational speeds
    then get AC servos....at double the money!!!

    Craig



  9. #9
    Member
    Join Date
    Jan 2018
    Location
    United Kingdom
    Posts
    1516
    Downloads
    0
    Uploads
    0

    Default Re: Which Stepper Would Be A Better Buy?

    I'm happy enough with this one:
    https://www.ebay.co.uk/itm/1-PC-Nema...72.m2749.l2649
    Wired in parallel. Smooth and quiet.



  10. #10
    Member
    Join Date
    Nov 2013
    Posts
    4280
    Downloads
    0
    Uploads
    0

    Default Re: Which Stepper Would Be A Better Buy?

    Hi,
    the true determinant on how fast a stepper can go before it loses enough torque that it starts missing steps is called the 'inductive time constant'.
    It is the product of inductance and resistance. For example the motor that dazp1976 linked to has resistance of 0.8 and an inductance of 3.5mH.

    Time constant =0.8 x 3.5
    =2.8ms......not bad but not great.

    And this one linked to by OP:
    https://www.amazon.com/gp/product/B0...PTXF2T90&psc=1
    has a resistance of 0.7 Ohm and 7.9mH

    Time constant= 0.7 x 7.9
    =5.53ms...….worse.

    This stepper:
    https://www.automationtechnologiesin...-single-shaft/
    has a resistance of 0.27 and an inductance of 1.65mH

    Time constant= 0.27 x 1.65
    =0.445ms or 445us, way WAY better than the first two, but note it is only 465 oz.in

    But check out this:
    Object reference not set to an instance of an object.
    has a resistance of 0.26 Ohm and an inductance of 1.18mH

    Time constant=0.26 x 1.18mH
    =0.306ms or 306us and so this 23 size stepper is the fastest of the lot. Note that its rated holding torque is 3.1Nm so is less torquey than the 34 size steppers but because it has
    such a low inductance it will spin really fast and at speed it may have MORE torque than the bigger motors , simply because they have greater inductance.

    Craig



  11. #11
    Member
    Join Date
    Sep 2005
    Location
    Indonesia
    Posts
    1195
    Downloads
    0
    Uploads
    0

    Default Re: Which Stepper Would Be A Better Buy?

    Which power supply work best on the stepper between switching power supply and toroidal power supply ? The toroidal PS is the output rectified and put capacitor in parallel.



  12. #12
    Member
    Join Date
    Jan 2012
    Location
    usa
    Posts
    163
    Downloads
    0
    Uploads
    0

    Default Re: Which Stepper Would Be A Better Buy?

    does the diver play a big part in performance too?



  13. #13
    Member
    Join Date
    Nov 2013
    Posts
    4280
    Downloads
    0
    Uploads
    0

    Default Re: Which Stepper Would Be A Better Buy?

    Hi,
    Which power supply work best on the stepper between switching power supply and toroidal power supply ?
    Toroidal power supplies are much better suited to temporary overload and are recommended.

    does the diver play a big part in performance too?
    I'm going to assume you haven't bought a rubbish drive and that any drive you chose can accurately control currents and does a good job of microstepping.
    That being the case the drive plays a lesser role, the only time they come to attention is if they blow up. In this regard Geckos are the gold standard of reliability.

    There are any number of manufacturers touting closed loop stepper drives and making all sorts of claims about increased power, speed etc......90% of it
    is just hype. Closing a control loop around a stepper DOES NOT ALTER THE PHYSICS OF THE STEPPER, if an open loop stepper loses torque at speed (and ALL do)
    then a closed loop stepper loses torque at speed. If a closed loop stepper misses a step due to overload the drive will insert an extra step to try to catch up.....but guess
    what.....the stepper is overloaded so the extra step suffer the same fate....ie it gets missed too.

    If you want genuine closed loop performance and generous overload capacity get AC servos.

    Craig



  14. #14
    Member
    Join Date
    Jan 2018
    Location
    United Kingdom
    Posts
    1516
    Downloads
    0
    Uploads
    0

    Default Re: Which Stepper Would Be A Better Buy?

    Quote Originally Posted by joeavaerage View Post
    Hi,
    the true determinant on how fast a stepper can go before it loses enough torque that it starts missing steps is called the 'inductive time constant'.
    It is the product of inductance and resistance. For example the motor that dazp1976 linked to has resistance of 0.8 and an inductance of 3.5mH.

    Time constant =0.8 x 3.5
    =2.8ms......not bad but not great.

    And this one linked to by OP:
    https://www.amazon.com/gp/product/B0...PTXF2T90&psc=1
    has a resistance of 0.7 Ohm and 7.9mH

    Time constant= 0.7 x 7.9
    =5.53ms...….worse.

    This stepper:
    https://www.automationtechnologiesin...-single-shaft/
    has a resistance of 0.27 and an inductance of 1.65mH

    Time constant= 0.27 x 1.65
    =0.445ms or 445us, way WAY better than the first two, but note it is only 465 oz.in

    But check out this:
    Object reference not set to an instance of an object.
    has a resistance of 0.26 Ohm and an inductance of 1.18mH

    Time constant=0.26 x 1.18mH
    =0.306ms or 306us and so this 23 size stepper is the fastest of the lot. Note that its rated holding torque is 3.1Nm so is less torquey than the 34 size steppers but because it has
    such a low inductance it will spin really fast and at speed it may have MORE torque than the bigger motors , simply because they have greater inductance.

    Craig
    I went for the best of the worst.
    The u.k. is a bit rubbish for getting stuff.
    I've gone to 2000mm/min rapids so far with a basic 7.8A max driver on 60V DC.

    That speed will do for now. Plenty happy with the acceleration of it however.



Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  


About CNCzone.com

    We are the largest and most active discussion forum for manufacturing industry. The site is 100% free to join and use, so join today!

Follow us on


Our Brands

Which Stepper Would Be A Better Buy?

Which Stepper Would Be A Better Buy?