Thoughts on this stepper/lead screw combination


Page 1 of 3 123 LastLast
Results 1 to 20 of 42

Thread: Thoughts on this stepper/lead screw combination

  1. #1
    Member Dock7676's Avatar
    Join Date
    Jan 2020
    Posts
    29
    Downloads
    0
    Uploads
    0

    Default Thoughts on this stepper/lead screw combination

    Hi guys,
    Currently building my second CNC router and was wondering if anyone could give me some input on this combination of stepper/driver kit and ballscrews.

    My current build is going to be a 48x60" table with a 3060 t-slot gantry, linear rails. Not the highest quality components lol, but i will upgrade as necessary once the machine is up and running. I already have these components, so hoping that they will perform, but input from some pro's would be greatly appreciated!

    linear rail with 1605 ballscrew kit 2000mm:
    https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

    Stepper/Driver kit - nema 23 425oz - (I do not plan on using this controller):
    https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

    Similar Threads:


  2. #2
    Member CitizenOfDreams's Avatar
    Join Date
    Nov 2012
    Location
    USA
    Posts
    1267
    Downloads
    4
    Uploads
    0

    Default Re: Thoughts on this stepper/lead screw combination

    The rails are OK, in my opinion. The drivers are OK too, for what they are.
    The motors are not the best for this application. The seller proudly states 425oz of torque but "forgets" to mention the inductance of 6.8mH (which means the motors will be painfully slow with a 36V power supply).
    The 1605 screw would probably be too slow for you as well, especially combined with those slow motors.



  3. #3
    Member Dock7676's Avatar
    Join Date
    Jan 2020
    Posts
    29
    Downloads
    0
    Uploads
    0

    Default Re: Thoughts on this stepper/lead screw combination

    Thank you for the reply! I was concerned that the setup was going to be slow after a bit of research and you have confirmed that for me. Any suggestions for a faster stepper/driver combination? Or will I be driving the ballscrews too fast with a faster stepper? I cannot send back the ballscrews, so I would like to use them for now and upgrade in the future if possible. Would I be better getting a larger stepper so that I will have more torque to drive a higher pitch lead screw in the future?

    Thanks again!



  4. #4
    Member ger21's Avatar
    Join Date
    Mar 2003
    Location
    Shelby Township
    Posts
    35538
    Downloads
    1
    Uploads
    0

    Default Re: Thoughts on this stepper/lead screw combination

    Both the stepper and screw are a poor choice, and even worse together.
    I'd use 6110 or 2010 screws.

    Choice of motor depends on the drives you plan on using.
    My choice would be a 400-450oz 6A Nema 34 with a high quality Leadshine or Gecko drive, and 60V.

    Gerry

    UCCNC 2017 Screenset
    [URL]http://www.thecncwoodworker.com/2017.html[/URL]

    Mach3 2010 Screenset
    [URL]http://www.thecncwoodworker.com/2010.html[/URL]

    JointCAM - CNC Dovetails & Box Joints
    [URL]http://www.g-forcecnc.com/jointcam.html[/URL]

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)


  5. #5
    Member Dock7676's Avatar
    Join Date
    Jan 2020
    Posts
    29
    Downloads
    0
    Uploads
    0

    Default Re: Thoughts on this stepper/lead screw combination

    Thanks Ger21, I am going to look into the leadshine drivers. I am try to find some low inductance steppers and probably move up to nema 34 in case I need the torque when changing ballscrews to 2010's in the future. I will also find a 60-80v power supply. I am hoping that a quality low inductance stepper and a higher voltage will allow me to spin the 1605 ballscrews up to 1200rpm or so for rapids/travel. This should allow me to at least jog the gantry around at I believe would be 236 in/min, right?

    I chucked the 2000mm 1605 screw in my drill quick and spun it up to 1200rpm (measured with a photo tachometer) with no signs of whip from the screw. I'm not sure how much faster it could be pushed or if I can even run a stepper any faster. Thoughts?



  6. #6
    Member
    Join Date
    Nov 2013
    Posts
    4282
    Downloads
    0
    Uploads
    0

    Default Re: Thoughts on this stepper/lead screw combination

    Hi,
    these Leadshine steppers have only 1.18mH inductance and with an 80V driver should run to 1200rpm:

    Object reference not set to an instance of an object.

    Object reference not set to an instance of an object.

    Craig



  7. #7
    Member Dock7676's Avatar
    Join Date
    Jan 2020
    Posts
    29
    Downloads
    0
    Uploads
    0

    Default Re: Thoughts on this stepper/lead screw combination

    Joeaverage. I can't seem to get pricing from that company, they have not emailed me back. What are the chances I can get a motor like this to run around 1200rpm?

    https://www.automationtechnologiesin...-single-shaft/
    According to the specs, it no looks like the inductance is only 1.65 (though 6 in parallel?). Is a nema 34 going to be slower than a nema 23, or is the driving factor in gaining rpm without loosing torque the inductance?



  8. #8
    Member
    Join Date
    Nov 2013
    Posts
    4282
    Downloads
    0
    Uploads
    0

    Default Re: Thoughts on this stepper/lead screw combination

    Hi,
    that motor is not too bad.

    The true measure of how a motor stacks up is called the 'inductive time constant' and is the product of the resistance and the inductance.

    For this (34 size) stepper the time constant = 1.65mH X 0.27 =0.445 ms or 445us, not too bad.

    The D57CM31 time constant = 1.18mH X 0.26 =.306ms or 306us. So it is potentially 45% faster than the bigger motor.

    In order for a stepper to go 1200rpm and still have enough torque to be useful will require a stepper with the lowest time constant you can find and
    driven by the highest voltage driver you can find. Cost and availability don't really come into it.....you are in rarefied territory here.

    I would suggest you look again at AC servos, they are a quantum leap up in performance.

    Craig



  9. #9
    Member
    Join Date
    Nov 2013
    Posts
    4282
    Downloads
    0
    Uploads
    0

    Default Re: Thoughts on this stepper/lead screw combination

    Hi,
    I found several listings like this:

    https://www.aliexpress.com/item/4000...archweb201603_

    Craig



  10. #10
    Member Dock7676's Avatar
    Join Date
    Jan 2020
    Posts
    29
    Downloads
    0
    Uploads
    0

    Default Re: Thoughts on this stepper/lead screw combination

    @joeaverage thank you for all of your help! You guys are an incredible resource! I was able to get through to leadshine today and have ordered the D57cm31 steppers you had suggested.

    Object reference not set to an instance of an object.

    I had also asked him about the driver that you had suggested and he did not have it in stock (steppers were not in stock either so they are being shipped from China)

    He had recommended a different driver instead. He said that the M880a driver may be a better option and he has them in stock

    Object reference not set to an instance of an object.

    I am not sure if he is just trying to sell me on his stocked driver or if they are also a good option. He said he would sell them for the same price as the drivers you had suggested.

    Also he only has 60v power supplies. Could you recommend a good source for a power supply closer to the 80v you had suggested?

    Thanks again for all of the help!



  11. #11
    Member ger21's Avatar
    Join Date
    Mar 2003
    Location
    Shelby Township
    Posts
    35538
    Downloads
    1
    Uploads
    0

    Default Re: Thoughts on this stepper/lead screw combination

    These are the power supplies I use.
    https://www.antekinc.com/

    Gerry

    UCCNC 2017 Screenset
    [URL]http://www.thecncwoodworker.com/2017.html[/URL]

    Mach3 2010 Screenset
    [URL]http://www.thecncwoodworker.com/2010.html[/URL]

    JointCAM - CNC Dovetails & Box Joints
    [URL]http://www.g-forcecnc.com/jointcam.html[/URL]

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)


  12. #12
    Member Dock7676's Avatar
    Join Date
    Jan 2020
    Posts
    29
    Downloads
    0
    Uploads
    0

    Default Re: Thoughts on this stepper/lead screw combination

    Also, how many amps of power should I shoot for? These are 6 amp steppers, I assume I do not need 24 amp worth of power supplies...but I am not sure what voltage the 6 amps is rated at.



  13. #13
    Member
    Join Date
    Nov 2013
    Posts
    4282
    Downloads
    0
    Uploads
    0

    Default Re: Thoughts on this stepper/lead screw combination

    Hi,
    good news. I'm sure the M880 will be fine.

    I think that an 80V supply like:

    https://www.antekinc.com/ps-10n80-10...-power-supply/

    as Gerry has recommended would be perfect.

    Craig



  14. #14
    Member
    Join Date
    Nov 2013
    Posts
    4282
    Downloads
    0
    Uploads
    0

    Default Re: Thoughts on this stepper/lead screw combination

    Hi,

    These are 6 amp steppers, I assume I do not need 24 amp worth of power supplies...but I am not sure what voltage the 6 amps is rated at.
    In the vast majority of cases not all four steppers will be active and therefore in general you don't need a 24 amp supply.

    You may recall the resistance spec of the D57CM31, 0.26 Ohm. If you applied 80VDC the current would be 80 /0.26=307A!!!
    Clearly the driver cannot connect 80VDC direct to the stepper continuously. In fact it applies the full 80VDC UNTIL the current gets
    to 6A and then enters a PWM mode to limit the current to 6A. If you like the high voltage (80V ) is to 'drive' the current through
    the coil as fast as possible but then back-off.

    At 6A the average voltage on the winding is 0.26 x 6= 1.56V
    Thus the driver will turn on for (1.56/80)=0.0195 or about 2% of the time and 98% off, called a 2% duty cycle.. This has the effect of a 'DC transformer',
    that is to say if the voltage is reduced by a buck regulator (which is in effect what a driver does) then the current increases
    by the same ratio.

    In our example the voltage is reduced from 80V to 1.56V or 0.0195. The current will increase by 80/1.56= 51 times!!!!
    So at 6A output the buck regulator will consume only 6 /51= 0.11A.

    Overall, when in PWM mode, that is to say most of the time, the driver will have 80V applied but consume only 0.11 A to produce
    1.56V and supply 6A. VERY CLEVER DON'T YOU THINK!!!.

    Thus the only time the driver will consume its full 6A is in that very short time where it direct connects the stepper to the 80V supply.
    Its not impossible that all four steppers may do this at the same time but unlikely. Therefore most people combine all the currents,
    in your case 4 x 6=24A and then halve it, ie 12A. You will see that is what I recommended (1000W, 12.5A at 80V). One of the advantages of transformer/rectifier
    power supplies is that they accommodate temporary overload MUCH MUCH better than switchmode supplies. Having said that if the price for a bigger
    1500W supply, that is 16.5A at 80V, is within your budget....get it.

    I suspect that when you get setup that you will find the steppers get intolerably warm, my Vexta steppers do. If you can easily achieve your speed/torque requirements
    you might consider running the steppers at 4A instead of 6A. They will run a lot cooler. Clearly you will also lose torque so you may not be able to reduce
    the current without losing steps.

    Another alternative is to thermally bond some aluminum heatsinks to the stepper body and may be even mount little PC fans on them.

    Either way you have spent some serious money to get some high performance steppers...enjoy.

    Craig



  15. #15
    Member peteeng's Avatar
    Join Date
    Jul 2018
    Location
    dum dum
    Posts
    6254
    Downloads
    0
    Uploads
    0

    Default Re: Thoughts on this stepper/lead screw combination

    Hi Dock - When you tested the whip of the 2000mm long 16mm dia ballscrew at 1200rpm did you hang it vertically? if so you maybe surprised when its horizontal. The force that perturbs the shaft is gravity and if its vertical then there is no perturbation. The hiwin formula says that a horizontal Dia16 screw 2000mm long will vibrate at 600rpm so you need to check this a bit further. If you had it between bearings on a bench then the hiwin formula is wrong.... Peter

    vib = (2.72e8)x0.689x12.9/2000^2 2000 length mm, 12.9 root dia of screw 0.689 fixity of ends (fixed and free bearing) 2.72e8 other constants

    I modelled a 2000mm shaft 12.9dia and the FE says it vibrates at 14.5htz (870rpm) if the ends are fixed or free. More Q,s??

    so Hiwin 600rpm I checked there is no safety margin in this
    FE 870 rpm

    and there are other equations with different answers so a real test is needed...

    Attached Thumbnails Attached Thumbnails Thoughts on this stepper/lead screw combination-whirl-speed-jpg   Thoughts on this stepper/lead screw combination-capture-jpg  
    Last edited by peteeng; 02-27-2020 at 05:55 AM.


  16. #16
    Member Dock7676's Avatar
    Join Date
    Jan 2020
    Posts
    29
    Downloads
    0
    Uploads
    0

    Default Re: Thoughts on this stepper/lead screw combination

    Thank you for the explanation Craig! I will order the Antek power supply that Gerry is using today.

    Peteeng, I ran the ballscrews laying horizontally on my workbench using the bearing blocks that were provided. I held the ballscrew and ran it the whole length of the screw multiple times with no whip.... I had tried running it at varying rpm's also. I even tried both 2000mm screws to make sure that I did not get a bent one. I am not sure how valid my test actually is, maybe things will change when the ballscrew is attached to a solid gantry? I also tried this without holding the ballscrew to see if holding it was preventing the whip.... If I have time I will take a video of it tonight



  17. #17
    Member ger21's Avatar
    Join Date
    Mar 2003
    Location
    Shelby Township
    Posts
    35538
    Downloads
    1
    Uploads
    0

    Default Re: Thoughts on this stepper/lead screw combination

    I don't know what drives you are using, but I'd be hesitant to use 80V with an 80V rated Chinese drive. I'd stay around 72V for a little headroom.

    Gerry

    UCCNC 2017 Screenset
    [URL]http://www.thecncwoodworker.com/2017.html[/URL]

    Mach3 2010 Screenset
    [URL]http://www.thecncwoodworker.com/2010.html[/URL]

    JointCAM - CNC Dovetails & Box Joints
    [URL]http://www.g-forcecnc.com/jointcam.html[/URL]

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)


  18. #18
    Member Dock7676's Avatar
    Join Date
    Jan 2020
    Posts
    29
    Downloads
    0
    Uploads
    0

    Default Re: Thoughts on this stepper/lead screw combination

    That is probably a good point Gerry. I was a little hesitant about maxing out the voltage of a driver. I will order the 72v instead.

    Also having a bit of analysis paralysis over the drivers. Is there any reason I cannot start with these? Just to keep the budget in check a bit and upgrade in the future if necessary. Will these DM860T limit me in any way over the EM882S or the M880A?

    https://www.amazon.com/STEPPERONLINE...2822514&sr=8-1

    I also don't want to over think the RPM issue, I know that I made the wrong decision with the 1605 lead screws and I am just trying to work around it by speeding up the steppers. I am trying to avoid yawning while I jog the machine, and hoping that it still cuts at a reasonable speed. 2010 screws are probably going to be an upgrade down the road.

    Thanks again for all your expertise guys. I will get some pictures up for constructive criticism once the table comes along a little further



  19. #19
    Member
    Join Date
    Nov 2013
    Posts
    4282
    Downloads
    0
    Uploads
    0

    Default Re: Thoughts on this stepper/lead screw combination

    Hi,

    I was a little hesitant about maxing out the voltage of a driver. I will order the 72v instead.
    You are throwing away 10% of your top speed, if the drive says 80V, get 80V. The DM860 drive you linked to is rated to 110VDC input.
    If you want the steppers to go fast then use the MAXIMUM voltage you can. If Chinese drives blow up at 80V get Geckos.

    You seem to be leaning to an upgrade to 2010 screws....why not an upgrade to Geckos instead?

    Craig



  20. #20
    Member Dock7676's Avatar
    Join Date
    Jan 2020
    Posts
    29
    Downloads
    0
    Uploads
    0

    Default Re: Thoughts on this stepper/lead screw combination

    Ok I propose a compromise. The DM860T drivers with a 77v 1000watt Antek power supply

    https://www.antekinc.com/ps-10n77-10...-power-supply/

    - - - Updated - - -

    And to update to Gecko drives if and when the drivers fail.



Page 1 of 3 123 LastLast

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

Thoughts on this stepper/lead screw combination

Thoughts on this stepper/lead screw combination