1. Hey guyz. Welcome to the All New Phlatforum!



    Sign Up and take a look around. There are so many awesome new features.

    The Phlatforum is a place we can all hang out and

    have fun sharing our RC adventures!

  2. Dismiss Notice

stepper motor tweaks....

Discussion in 'MOTORS - Stepper Motors' started by rjarois, Dec 29, 2008.

  1. rjarois

    rjarois Moderator Staff Member

    Offline
    Messages:
    1,263
    Trophy Points:
    36
    Location:
    royal oak, michigan
    ok fellas, i have to admit im allright at things that are mechanical, but when it comes to electronics im a idiot....on the steppers i got it says 1.2 volt. acording to the info from the board you use a volt meter and set the pot to 2.4 volts. i did that and the motors get real hot, like 140deg. is this normal?? also i was wondering if you guys can post your motor set-up info. like the accel and velocity settings for the different axis?. thanks you will be helping a idiot........randy.
     
  2. firetrappe

    firetrappe Member

    Offline
    Messages:
    192
    Trophy Points:
    16
    Location:
    England UK
    Randy, assuming that you're using the steppers and board from Easy-Cnc then they have advised a few people not to set the vref above 1.6V . You are correct that the manual for the board says to set the vref to 2x the required current, but I don't think this is safe with the supplied steppers.

    FYI I have all my vref's set to 1.6V, and all axes tuned to Accel=20 and Velocity=40.
    The only mod I have made to the PP is to upgrade the y-axis stepper, all other components are the ones I received with my PhlatPremium kit.

    Hope this helps.
    Si.
     
  3. rcav8r

    rcav8r Moderator Staff Member

    Offline
    Messages:
    1,193
    Trophy Points:
    38
    FWIW, I set my vrefs to 1.2 as that is what I understood it to be set by reading the label on the motors I got. When I was able to run all 3 axis, the steppers were only slightly warm to the touch, as were the heat sinks. I was having problems w/ my Y-axis, so I tweaked the Y vref to about 1.8-2.0 and tried it. No change on the Y, so I backed it back down. I also noticed no real heating of the Y-motor or heat sink, but it was that way only for a minute or two. A little later the Y motor started to chatter even w/ no load, so it is in the process of being replaced.
     
  4. rjarois

    rjarois Moderator Staff Member

    Offline
    Messages:
    1,263
    Trophy Points:
    36
    Location:
    royal oak, michigan
    firetrappe, i set the voltages down to 2.0v acording to the manual that would be 1.0v instead of 1.2v the motors are still checking @140f. this to hot ya think?
     
  5. rjarois

    rjarois Moderator Staff Member

    Offline
    Messages:
    1,263
    Trophy Points:
    36
    Location:
    royal oak, michigan
    rcav8r, from the example, you would double 1.2v and set board for that. it would be 2.4v on each axis. randy
    [​IMG]
     
  6. rcav8r

    rcav8r Moderator Staff Member

    Offline
    Messages:
    1,193
    Trophy Points:
    38
    Yep, I read that part... but my motors have a pre-printed label that says "Adjust vref to ________volts, and 1.2 is hand written in the blank, so I was assuming that meant that's what to adjust them to. i.e the calculation was already done. They are still set like that and I was able to get 80 on my X axis when playing with EMC yesterday. It zipped the foam back and forth with ease, and the measurements were spot on after a few cycles. At this point I see no reason to change the vref, but may when I can actually cut some foam.
    Probably could have did more than 80 on the X, I'm going to back it way down when actually cutting, but I have a Z axis issue I need to sort out in EMC. Works fine in Mach, so I'm sure the stepper and board are OK.

    Also I just checked and on the build log on the web page, it has a correction to set the vref to 1.2v
    Thanks
    Dave Attached files [​IMG]
     
  7. firetrappe

    firetrappe Member

    Offline
    Messages:
    192
    Trophy Points:
    16
    Location:
    England UK
    Randy, my steppers get warm but never hot. I'm not sure of the exact temperature, but they don't get warm until they've been on for around 15mins. My heatsinks on my driver board are always cooler than the motors. I'll try and get some temp readings for you tomorrow when i've been cutting for a while.

    Regarding the vref settings for the supplied motors, have a look at this post on RCG which contains the response that tvcasualty got from Easy-CNC when he asked a similar question : http://www.rcgroups.com/forums/showpost ... count=1684

    Si.
     
  8. Flashsolutions

    Flashsolutions Active Member

    Offline
    Messages:
    1,123
    Trophy Points:
    38
    Location:
    Leesburg, Florida
    I've posted this before on RC Groups, but it should be mentioned again here....

    These motors should not run hot! If they do, you are risking shorting the windings as I did. I burned up 3 stepper motors following the instructions to set the pots to mid position (2.4V).

    The 90oz inch steppers from easy-cnc do not have enough power to run the Y axis at much more than 14 inches per minute. I replaced my steppers with higher current NEMA 23 steppers which can handle the 2.4 to 5 volt range without getting hot and they will give you the higher rates you are seeking.

    Faster rates is not always a good thing. It puts more stress on the gantry and to get good clean cuts in higher density foam or multiple sheets, it is often necessary to drop the feed rate anyway.

    Rule of thumb... If the stepper is running hot, the windings are very likely going to short out!

    The windings should read about 11 ohms with an ohmeter. If the windings short, you will find one or more reading anywhere from 1 to 8 ohms in which case, you will need to replace the stepper.

    The 1.2 volts that easy-cnc recommends works very well for those steppers and they run cool as intended, but forget about driving the Y axis fast. After the threads are well broken in, you might be able to tune the steppers for better performance.
     
  9. kyyu

    kyyu Active Member

    Offline
    Messages:
    1,183
    Trophy Points:
    36
    Location:
    Maryland
    rjarois,

    If you haven't figure it out yet, you are using the equation wrong. The motor label says set Vref to 1.2V. That what you set on the driver board. What you are tring to do is double Vref and then say that's really Vref.

    The equation for Vref is Vref=2xCurrent. Bascially setting the Vref on the board to a value of 1.2V, is really setting the current to 0.6A.

    So that's what you want to set, 1.2V not 2.4V.

    -Kwok
     
  10. rjarois

    rjarois Moderator Staff Member

    Offline
    Messages:
    1,263
    Trophy Points:
    36
    Location:
    royal oak, michigan
    cool, i will try to reset @1.2v i talked to a friend that knows alot about this stuff and he told me the motors are cheezy to say the least.....now i know why the fellas are gettin new ones. randy.
     
  11. dbtoutfit

    dbtoutfit New Member

    Offline
    Messages:
    105
    Trophy Points:
    0
    Location:
    Alabama
    I would really double check to make sure the IC is not bad before I grabbed a new stepper motor.

    This is exactly what happens when IC's go bad.

    Hook another (good) known stepper motor to the terminals and jog see what you get.

    Incase you havent done this.

    Eric
     
  12. rjarois

    rjarois Moderator Staff Member

    Offline
    Messages:
    1,263
    Trophy Points:
    36
    Location:
    royal oak, michigan
    got a new y-axis tweak....a new 175oz stepper. also i am working over the screw....i will update this in my mod posts. randy.
     
  13. rcav8r

    rcav8r Moderator Staff Member

    Offline
    Messages:
    1,193
    Trophy Points:
    38
    Yep did this. Swapped with the X axis. Issue followed the Y stepper.
    Thanks
     
  14. rjarois

    rjarois Moderator Staff Member

    Offline
    Messages:
    1,263
    Trophy Points:
    36
    Location:
    royal oak, michigan
    can you fellas tell a idiot monkey what a ic is??
     
  15. kram242

    kram242 Administrator Staff Member

    Offline
    Messages:
    6,311
    Trophy Points:
    13
    Location:
    NJ
    I can't tell an idiot but I can tell a guy who is asking for help :)
    IC's are Integrated Circuits they are the chips on your driver board.
    Mark
     
  16. rjarois

    rjarois Moderator Staff Member

    Offline
    Messages:
    1,263
    Trophy Points:
    36
    Location:
    royal oak, michigan
    thanks, mark...i have such a lack of knowledge pertaining to electronics....i feel stupid on the topic....hardware, mechanical, man im all up on that, lols. electrical man forget me, lols. hey mark, that brings another question, or anyone that can answer it.....my common sence tells me that the slower the accell rate is, the more velocity you can get. is this true or not?? these stepper motors work like magic to me lols. randy.
     
  17. dangre

    dangre New Member

    Offline
    Messages:
    26
    Trophy Points:
    0
    rj, think of it like velocity (speed) of a race car. The faster you go, the more likely you loose control due to aerodynamics or road slip. Accelerate to fast and you have the same issues. They are completely seperate but work together.
    As to your question, your max velocity will never be obtained if your acceleration is too high (Top fuel drag racer on ice). Set your acceleration low and then increase your max velocity until you get missed steps. You need to test the entire axis travel at this velocity settings to make sure you don't have any 'bumps' in your leadscrew/linearways. Once you have your max velocity set, increase your acceleration until it looses steps. (reduce max settings +/-80% to obtain consistant results)
     
  18. dbtoutfit

    dbtoutfit New Member

    Offline
    Messages:
    105
    Trophy Points:
    0
    Location:
    Alabama
    So its the motor. good deal.

    Eric
     
  19. kram242

    kram242 Administrator Staff Member

    Offline
    Messages:
    6,311
    Trophy Points:
    13
    Location:
    NJ
    Well said dangre, , thank you for a great explaination. :)
     
  20. rjarois

    rjarois Moderator Staff Member

    Offline
    Messages:
    1,263
    Trophy Points:
    36
    Location:
    royal oak, michigan
    yea, thanks dangre.....that makes tuning the motors better for me knowing what im doing now. randy.
     
  21. rjarois

    rjarois Moderator Staff Member

    Offline
    Messages:
    1,263
    Trophy Points:
    36
    Location:
    royal oak, michigan
    ok fellas, the electronics idiot is back, with another question.....got my new stepper motor for my y-axis, and the instructions show the coil drawing. they show the two coils with the wire colors that go together, but not whats the plus and minus. my question is how do you dertime whats the A-plus and whats the A-minus?? please help the electronic challenged...thanks, randy.
    link to the motor. with the directions...http://stepper3.com/shop/stepper3-ozin-wire-aphase-p-83.html
     
  22. TigerPilot

    TigerPilot Well-Known Member

    Offline
    Messages:
    1,578
    Trophy Points:
    48
    Use the black as the '+' for A and the green as the '-' for A. Use the red as the '+' for B and the blue as the '-' for B. If the motor runs the wrong way you can change it in Mach3.

    Yoram
     
  23. kyyu

    kyyu Active Member

    Offline
    Messages:
    1,183
    Trophy Points:
    36
    Location:
    Maryland
    rjarois, I didn't know, either about how to wire the stepper. So google and found some extra info, quoted below. Seems it doesn't matter what is - or +. And it's kind of like our brushless motors; just reverse any coil if it turns the wrong way:
    http://reviews.ebay.com/Stepper-Motor-T ... 0001227707

    "To reverse the direction of a stepper motor just reverse the two main phase wires of one phase pair. Reversing both pairs has no effect."

    -Kwok
     
  24. rjarois

    rjarois Moderator Staff Member

    Offline
    Messages:
    1,263
    Trophy Points:
    36
    Location:
    royal oak, michigan
    thanks alot fellas...man i can hardly change a light bulb, randy.
     
  25. rjarois

    rjarois Moderator Staff Member

    Offline
    Messages:
    1,263
    Trophy Points:
    36
    Location:
    royal oak, michigan
    fellas, i cut out a control cover cover out of foam, and installed a 120mm fan on it. anyone know if i can tweak the voltage up a little? if so fow much can i go. i have two stock 1.2v and one thats 2.5v. also would the motors run better by doing so? i am very weak with the electrical end of this stuff, but wanna learn. randy.
     

Share This Page