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First layer question


braddock

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Posted · First layer question

Hey guys, I've been keeping an eye on this for a while, and ever since having a few layer shift issues, I'm paying more attention than usual to certain things, looking for belt slip or other things.

My first layer usually looks like this, a slight gap between each line that goes down... usually by the time the 1.2mm bottom is complete, it's nice and smooth, but is it normal to have these gaps between lines?

 

first layer

 

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    Posted · First layer question

    I think you have to check the other side: the visible one. If this side is OK...

    However, it seems you have a low temp or underextrusion or a bad levelled bed... anyway, check the other side...

     

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    Posted · First layer question

    I don't know if this helps but i found that printing the first layers a 230°c gives a better result. The lines are more pressed together.

    I don't think you have a levelling issue because your brim looks good to me

     

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    Posted · First layer question

    First layer looks good, second layer has unexpected gaps. Is your infill set to 70% or something? Did you change flow to less than 100%?

    Some people have overextrusion on first layer and fix it by lowering flow to 90% instead of lowering the bed by 10% of the first layer thickness.

    This looks like typical underextrusion on a UM Original, but underextrusion on the UM2 tends to have sudden slip backs of the feeder such that you have obvious spots where there is zero extrusion. This more looks like something on purpose such as the first two things I mentioned.

     

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    Posted · First layer question

    Well, the brim is perfect, so I don't believe the bed needs leveling. These layers were at 240 - 0.08 layer height.

    It's not under extruding, the rest of the print is perfect, walls are perfect. I had this printing at 50mm/s when I slowed it down, the gaps went away.

    I've not changed the flow at all.

     

     

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    Posted · First layer question

    To clarify, it's not under extrusion as I know it on the UM2, it's consistent, and has no negative effect on the rest of the print.

    The consensus from you guys though, is that it is flow / extrusion related and not a mechanical loss of precision.

    Perhaps with this filament I could try increasing the flow on the first layers.

     

     

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    Posted · First layer question

    The consensus from you guys though, is that it is flow / extrusion related and not a mechanical loss of precision.

     

     

    Yes. Mechanical issues look different - typically two close together lines and then a gap and then repeat.

     

    Perhaps with this filament I could try increasing the flow on the first layers.

     

    Better to print slower. Are you sure these gaps aren't on purpose by the slicer? Maybe open the gcode in repetier host (it's free) and see if it also thinks there are expected gaps?

     

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