1. Got a question or need help troubleshooting? Post to the troubleshooting forum or Search the forums!

Recommendation requested for a smaller & lighter NEMA 17 extruder servo.

Discussion in 'Mods and Upgrades' started by BrooklynBay, Mar 19, 2019.

  1. BrooklynBay

    BrooklynBay Active Member

    Joined:
    Apr 7, 2018
    Messages:
    220
    Likes Received:
    28
    I've recently upgraded my Robo 3D R1 to use a Flexion extruder with adapters. The large NEMA 17 servo which came with the original Greg's - Wade extruder is being used but it's very bulky. I've looked at many smaller NEMA 17 low profile servos, but the strength in ounces is considerably lower than what I have now. I don't know if they make a NEMA 17 which has the same steps, degrees, and force in the low profile versions. I've seen some versions on Amazon which use rare Earth magnets to make them stronger but the specifications are still about half the pushing force of the stock large servo. Is it possible to get a strong low profile servo?
     
  2. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
    Staff Member

    Joined:
    Feb 21, 2013
    Messages:
    21,137
    Likes Received:
    6,997
    Nema 17 specifies the face and mounting so by "smaller" I assume you mean "not as thick"

    There are a few out there, but many will have less torque (smaller windings). Look around Amazon with the numbers you want to match. There are a lot of NEMA 17 steppers on there. You want 1.8 degrees/step rather than 0.9 (unless you redo the firmware).

    Example: https://smile.amazon.com/Stepper-36-8oz-Printer-Machine-Robotics/dp/B07582D2R8
     
  3. BrooklynBay

    BrooklynBay Active Member

    Joined:
    Apr 7, 2018
    Messages:
    220
    Likes Received:
    28
    Thanks for your reply. The profile of this servo is lower but so is its torque rating. I've been looking for a low profile model with similar torque like the full size version but didn't find anything.
     
  4. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
    Staff Member

    Joined:
    Feb 21, 2013
    Messages:
    21,137
    Likes Received:
    6,997
    Not likely going to happen.
    You don't need a ton of torque for the extruder motor (it is geared on the R1/R1+)

    However, like I said -- look around :) If you know what size you want and torque numbers you want it is just a search and discovery mission. You might also try Pololu directly: https://www.pololu.com/category/87/stepper-motors

    Excellent products. Something like their little pancake would probably work fine:

    https://www.pololu.com/product/2296
     
  5. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
    Staff Member

    Joined:
    Feb 21, 2013
    Messages:
    21,137
    Likes Received:
    6,997
    Of course the more torque you can get the merrier -- not like having too much is a problem :)
     
  6. BrooklynBay

    BrooklynBay Active Member

    Joined:
    Apr 7, 2018
    Messages:
    220
    Likes Received:
    28
    Since I have a Flexion extruder, there is no gearing like the previous Greg's - Wade configuration. It's a direct drive system, and might not work correctly with a low torque servo. The servos in that link show low profile servos with very low torque. I'm looking for a servo which is 20mm or less deep. The pancake servo in the above link or the second one which is small in another link are a good size if they are strong enough. The voltage rating might be too low.
     
    #6 BrooklynBay, Mar 19, 2019
    Last edited: Mar 19, 2019
  7. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
    Staff Member

    Joined:
    Feb 21, 2013
    Messages:
    21,137
    Likes Received:
    6,997
    Voltage is irrelevant since it is provided by the pololu stepper driver.
    Current is what matters, not voltage.
     
  8. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
    Staff Member

    Joined:
    Feb 21, 2013
    Messages:
    21,137
    Likes Received:
    6,997
    For what it is worth we use direct drive steppers in all of the other printers (delta, C2, etc.) and the ones I linked to on Amazon are more than sufficient . Not using that specific Extruder (the Flexion) so you want to see what they suggest.
     
  9. BrooklynBay

    BrooklynBay Active Member

    Joined:
    Apr 7, 2018
    Messages:
    220
    Likes Received:
    28
    The length of the shaft of the stock servo is a perfect fit. The low profile servos look like they have shorter shafts.
     
  10. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
    Staff Member

    Joined:
    Feb 21, 2013
    Messages:
    21,137
    Likes Received:
    6,997
    Some do. You need to take the specs you want and compare against all of them out there :)
    If shaft length and torque are some of the requirements... and size ... you need to go huntin'
    These guys have a long list:

    https://www.electromate.com/nema-frame-step-motors.html

    You may not need Nema 17 (although you probably do seeing how the extruder you are using mounts to the face)
    Motor specs are somewhat tied to dimensions which is why smaller ones tend to have less torque (although that is not always true, it is a general rule of thumb)

    You may find that to get something specific may be a lot more expensive :)
     
  11. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
    Staff Member

    Joined:
    Feb 21, 2013
    Messages:
    21,137
    Likes Received:
    6,997
    Sadly NEMA 17 only specifies the face of the motor and mounting points.
    So there are a lot of possibilities.
     
  12. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
    Staff Member

    Joined:
    Feb 21, 2013
    Messages:
    21,137
    Likes Received:
    6,997
    I wish someone had a more generic stepper motor locator :)
    Sadly there are so many different ones made by various companies that it is not the case.
    If you are not in a hurry* you can look around BangGood: https://www.banggood.com/3D-Printer...otor-300mN-1_5A-2-phase-4-wire-p-1064247.html

    Theirs will be usually the cheapest.





    *I say that because they don't ship quickly. In the US it will take 3-8 weeks for stuff to show up
     
    #12 mark tomlinson, Mar 19, 2019
    Last edited: Mar 19, 2019
  13. BrooklynBay

    BrooklynBay Active Member

    Joined:
    Apr 7, 2018
    Messages:
    220
    Likes Received:
    28
    Customer service emailed me. They said that they recommend not going below 250 N/MM. I guess this rules out most of the pancake style servos. I saw a few servos which are a few millimeters shorter than what I have now with less torque so it's not too much of an improvement.
     
  14. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
    Staff Member

    Joined:
    Feb 21, 2013
    Messages:
    21,137
    Likes Received:
    6,997
    Was afraid that was the answer.
    If there is another mounting style that works (NEMA 23 or something) then you might have more options.
    This is why folks go bowden (particularly if they do mutliple extruders) since trying to add the weight of the steppers is awkward and you move slower.
     
    Geof likes this.
  15. BrooklynBay

    BrooklynBay Active Member

    Joined:
    Apr 7, 2018
    Messages:
    220
    Likes Received:
    28
    Just out of curiosity, which stepper driver does the R1 come with just in case I ever need to get a replacement?
     
  16. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
    Staff Member

    Joined:
    Feb 21, 2013
    Messages:
    21,137
    Likes Received:
    6,997
  17. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
    Staff Member

    Joined:
    Feb 21, 2013
    Messages:
    21,137
    Likes Received:
    6,997
    BTW: Bowden conversions are not hard and there have been a couple for the R1 series and I did one for the C2 (added a second extruder that way). If you really want to do that.
     
  18. BrooklynBay

    BrooklynBay Active Member

    Joined:
    Apr 7, 2018
    Messages:
    220
    Likes Received:
    28
  19. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
    Staff Member

    Joined:
    Feb 21, 2013
    Messages:
    21,137
    Likes Received:
    6,997
    Yes, all A4988 drivers are the same electronics.
     
  20. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
    Staff Member

    Joined:
    Feb 21, 2013
    Messages:
    21,137
    Likes Received:
    6,997
    The only caution I will offer is that these are cheap Chinese components :)
    Sometimes they arrive non-functional. I usually just buy the all-in-one kits (RAMPS/Arduino Mega/stepper drivers) which are cheap enough and generally everything works.
     

Share This Page