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

Upgraded to metric rods

Discussion in 'Mods and Upgrades' started by Matthias, Dec 29, 2013.

  1. Melody Bliss

    Melody Bliss New Member

    Joined:
    Nov 17, 2013
    Messages:
    276
    Likes Received:
    81

    Contact Robo3D. They can probably send you a new coupler.
     
  2. Cmckinney

    Cmckinney New Member

    Joined:
    Feb 21, 2013
    Messages:
    6
    Likes Received:
    2
    Good idea. Im not going to bother them with that as I bent it ... note to self better allen wrenches!

    I measured them and ordered some.
    Specs are 5 x 8 mm 25mm length.
     
  3. Jay

    Jay New Member

    Joined:
    Jan 18, 2014
    Messages:
    12
    Likes Received:
    5
    I seem to be having the same problem Cmckinney, I've done the switch over to 8mm, 1.25 pitch metric rods and then printed a second calibration angle which was coming out a little shorter than the original which I expected. So I went to change the default z axis steps in the new Marlin_3_14_14 firmware

    From:
    #define DEFAULT_AXIS_STEPS_PER_UNIT {80,80,2267.72,723.38}
    To:
    #define DEFAULT_AXIS_STEPS_PER_UNIT {80,80,3200,723.38}


    Now it seems if I use the 3200 value I cannot home my Z axis. No idea why :(
     
  4. Ziggy

    Ziggy Moderator
    Staff Member

    Joined:
    Feb 20, 2013
    Messages:
    707
    Likes Received:
    530


    Your setting for M8 coarse (1.25mm pitch) rod needs to be

    #define DEFAULT_AXIS_STEPS_PER_UNIT {80,80,2560,723.38}

    check Repetier / tools / leadscrew calculator
     
  5. Jay

    Jay New Member

    Joined:
    Jan 18, 2014
    Messages:
    12
    Likes Received:
    5
    Thanks for the correction Ziggy, just realised earlier in the thread the rod pitch was 1mm rather than 1.25mm.

    Unfortunately even with the adjusted z step if I attempt to home the z axis the stepper motors seem to lock up and hum. If I go back to the default or lower than the default z axis step of 2267.72 it homes fine.

    Any ideas why that could be happening?
     
  6. Ziggy

    Ziggy Moderator
    Staff Member

    Joined:
    Feb 20, 2013
    Messages:
    707
    Likes Received:
    530
    Yes. I think so.

    I suggest you read this post and the whole thread.

    http://forums.robo3dprinter.com/index.php?threads/z-axis-precision-and-accuracy.1919/page-2

    You will see that the Robo guys don't recommend 8mm fine (1mm) pitch rods. The reason is the torque required from the steppers is too high.

    Even with 8mm coarse rods, the stepper torque (probably) needs to be adjusted a bit. In the same thread as earlier there is a link to a site which explains how to adjust the torque. It's not difficult to do and will cure the ugly noises and slip from the steppers.

    BTW I also suggest that you use 8mm nylon nuts on the Z Axis rods ( The newer Robos will also use nylon nuts I'm told). I changed mine from stainless to nylon and it is far quieter and smoother.
     
  7. SoLongSidekick

    SoLongSidekick Active Member

    Joined:
    Mar 6, 2014
    Messages:
    220
    Likes Received:
    68
    I have a bunch of black nylon nuts (M8x1.25) if anyone needs some. The greatest thing about these nuts is they fit perfectly in the X axis carriage, no sanding needed and it has zero play.
     
  8. Matthias

    Matthias Member

    Joined:
    Feb 20, 2013
    Messages:
    174
    Likes Received:
    18
    I currently use brass nuts. Works as well.
     
  9. Jay

    Jay New Member

    Joined:
    Jan 18, 2014
    Messages:
    12
    Likes Received:
    5
    Ta Ziggy, I'll have a play with the pots settings after work tonight. I do however find it strange I can move the Z axis up or down through cura/repetier but homing causes only the Z axis steppers to freak out.

    As Matthias mentioned I also switched to brass nuts, which fit correctly without shaving, but I will see if i can steal some of SoLong's nuts ;)
     
  10. Ziggy

    Ziggy Moderator
    Staff Member

    Joined:
    Feb 20, 2013
    Messages:
    707
    Likes Received:
    530
    Well any nut you don't have to shave is probably a good nut :)

    I suspect your stepper torque is just under the borderline. When you home, the steppers try to move faster than when they are moved manually using repetier.
     
  11. SoLongSidekick

    SoLongSidekick Active Member

    Joined:
    Mar 6, 2014
    Messages:
    220
    Likes Received:
    68

    That's odd, Jerry sent me some firmware that has these settings:

    #define DEFAULT_AXIS_STEPS_PER_UNIT {80.69,80.69,2560,747.626}
     
  12. Ziggy

    Ziggy Moderator
    Staff Member

    Joined:
    Feb 20, 2013
    Messages:
    707
    Likes Received:
    530

    I was only focussed on the Z axis steps and copied the other settings from the post. What ever Jerry sent for the other axis and extruder settings are bound to be current and correct.
     
  13. Jay

    Jay New Member

    Joined:
    Jan 18, 2014
    Messages:
    12
    Likes Received:
    5
    #define DEFAULT_AXIS_STEPS_PER_UNIT {80,80,2267.72,723.38} is the default in Marlin 3_14_14 firmware

    I think I have an older copy of the Marlin 2/4/14 firmware saved at home where the default was the settings Jerry sent you, minus the 2560 z step setting.
     
  14. SoLongSidekick

    SoLongSidekick Active Member

    Joined:
    Mar 6, 2014
    Messages:
    220
    Likes Received:
    68
    I have a dedicated hard drive just for Arduino/ATmel/PIC firmware, I always keep old versions. The 2/14 firmware has these settings:

    #define DEFAULT_AXIS_STEPS_PER_UNIT {80,80,2267.72,723.38}

    They must have refined the steps since the 3/14 firmware I guess, all the files in the firmware Jerry sent me were created on 4/1/2014 at ~10:13 AM. If anyone wants me to post the full firmware zip I will in case there are other changes as well.
     
    2 people like this.
  15. Deadwood

    Deadwood Active Member

    Joined:
    Jul 4, 2013
    Messages:
    119
    Likes Received:
    29
    I have just fitted metric rods M8 x 1.25 and printed a rather short looking 15 mm cube, I knew this would be the case and am now looking how to address this but per this post there seems to be a lot of confusion as to what the settings should be so to all the people who are using metric rods successfully what are the recommended settings that actually work ?
     
  16. SoLongSidekick

    SoLongSidekick Active Member

    Joined:
    Mar 6, 2014
    Messages:
    220
    Likes Received:
    68
    I live in San Diego and am actually heading over to R3D headquarters today to sit down with Jerry and hammer out the correct settings and get this working. I will report back once that happens.
     
  17. Deadwood

    Deadwood Active Member

    Joined:
    Jul 4, 2013
    Messages:
    119
    Likes Received:
    29
    cheers, I wait in anticipation
     
  18. Deadwood

    Deadwood Active Member

    Joined:
    Jul 4, 2013
    Messages:
    119
    Likes Received:
    29
    incidentally even though the Z height is now incorrect the print has a much better quality to it, the striping is less and I am hoping a new coupler to replace my eccentric one will help even more but the overall appearance of the sides seems a lot tighter and neater, it may just me but hey its me that counts in terms of what I am printing :)
     
  19. Matthias

    Matthias Member

    Joined:
    Feb 20, 2013
    Messages:
    174
    Likes Received:
    18
    There are calculators for the steps of there. I think I used one for a Prusa, but it doesn't really matter.
    I believe 80,80,2560 are the right ones.
    Don't have a link handy, just ask google ;-)
     
  20. SteveC

    SteveC Well-Known Member

    Joined:
    Jun 12, 2013
    Messages:
    894
    Likes Received:
    316
    Just put this in the shoutbox for Deadwood: http://calculator.josefprusa.cz/. The defaults look right for the M8x1.25 rod.
     

Share This Page