SOLVED Newer 8mm-Pitch Leadscrews & Nuts.

Discussion in 'Build Help' started by fpex, Jun 15, 2016.

  1. fpex

    fpex Well-Known Member

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    I was looking at the instructions again for recalibrating things, did the z axis change?
     
  2. PsyVision

    PsyVision Moderator
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    Change in what way?
     
  3. fpex

    fpex Well-Known Member

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    This is what I am asking. The instruction now mentions a new 8mm lead screw needing a different Estep of 400
     
  4. PsyVision

    PsyVision Moderator
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    Looks like they have, a change in 2mm to 8mm would require 1600 to 400. Interesting. @Greg Holloway any input?
     
  5. Sarah Nicholson

    Sarah Nicholson Well-Known Member

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    Hmm, this could be a bit confusing for some people. My 1.1 kit appears to have the older leadscrews, but I received two different brass nuts, one with 8 holes (which according to the wiki is the old version) and one with 4 holes. I guess since my Z axis is working correctly they must be the same pitch?
     
  6. Alex9779

    Alex9779 Moderator
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    You are not able to screw the screw in a nut with a different pitch... Depending on play at about 0.5mm difference it will not work anymore or only with some force...
    The ones with the 8 holes were the ones from the KS campaign with the wagon hole size they reworked. Drilling some holes was faster then reproduction...
     
  7. PsyVision

    PsyVision Moderator
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    I don't think deciding whether you have 2 or 8 pitch will be too much trouble for most but I am intrigued to know what might be the print benefits of such a change. I can't find any 2mm vs 8mm pages from a quick Google search but note that a number of 3D shops (and banggood) are selling 8mm pitch.
     
  8. Sarah Nicholson

    Sarah Nicholson Well-Known Member

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    Yep, I figured it would be obvious if it was wrong :) But the point is that there are clearly a few 2mm pitch brass nuts with 4 holes in them which could cause confusion. Maybe I was just lucky and got the only leftover 4 hole one from before they had them all re-machined...
     
  9. Alex9779

    Alex9779 Moderator
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    From an engineering point of view I would say you reduce the "stick in place" effect a bit. The motor have to use more of their torque to move the bed because of the reduced "self retaining" (is that correct? my dictionary gave me no specific word for "Selbsthemmung")...
     
  10. Alex9779

    Alex9779 Moderator
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    I think the other way: you have the very last re-machined nut! Then they stocked 2mm pith nuts which were produced with the correct holes...
     
  11. PsyVision

    PsyVision Moderator
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    I suspect you're about right there.
     
  12. mike01hu

    mike01hu Well-Known Member

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    "Stiction" may be what you are looking for which is a made-up word to describe sticking due to friction.
     
    #12 mike01hu, Jun 16, 2016
    Last edited: Jun 16, 2016
  13. Mark_T

    Mark_T Well-Known Member

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    This is the text from the manual:

    That is a pretty dramatic change in resolution.
     
  14. Mark_T

    Mark_T Well-Known Member

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    I may be misunderstanding this, but if you have an 8mm pitch how exactly do you get a 50micron layer height?

    It seems like you could get 40 or 60 microns but not 50?

    With 8mm your minimum Z change is going to be 20 microns whereas with a 2mm pitch it was 1.25 microns?
     
  15. PsyVision

    PsyVision Moderator
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    The steps/mm change from 1600 to 400 so you rotate the lead screw less than before but it will still move the bed up and down the same amount as before and achieve the same resolution as before.
     
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  16. Mark_T

    Mark_T Well-Known Member

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    Makes sense, I missed the point that it was steps per mm, not steps per revolution of the screw.
     
  17. fpex

    fpex Well-Known Member

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    I have printers with several pitches and the change in resolution is not visible, if it ever exists.
    I am happy to know that my value of 3200 is correct (I use 400 step motor for Z)
     
  18. Mark_T

    Mark_T Well-Known Member

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    ... and for the new 8mm version that would presumably be 800 with the -400 motors?
     
  19. fpex

    fpex Well-Known Member

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    Yes, double it and then fine tune
     
  20. Alex9779

    Alex9779 Moderator
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    I think now we know why the very first released Hybrid firmware by Greg had 400 steps/mm for the Z axis...
     
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