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Discussion in 'Build Help' started by fpex, Jun 15, 2016.
I was looking at the instructions again for recalibrating things, did the z axis change?
Change in what way?
This is what I am asking. The instruction now mentions a new 8mm lead screw needing a different Estep of 400
Looks like they have, a change in 2mm to 8mm would require 1600 to 400. Interesting. @Greg Holloway any input?
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?
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...
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.
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...
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")...
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...
I suspect you're about right there.
"Stiction" may be what you are looking for which is a made-up word to describe sticking due to friction.
This is the text from the manual:
That is a pretty dramatic change in resolution.
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?
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.
Makes sense, I missed the point that it was steps per mm, not steps per revolution of the screw.
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)
... and for the new 8mm version that would presumably be 800 with the -400 motors?
Yes, double it and then fine tune
I think now we know why the very first released Hybrid firmware by Greg had 400 steps/mm for the Z axis...