First layer has thin and thick areas.

[fvarnell 0]

I really need some help figuring this out. My first layer has some areas that are .29mm and some are .37mm. Using and Ultimaker 3 extended.

I have the bed leveled and it doesn't seem to be an adhesion issue. Here are some of the relevant Cura settings. Using Ulti PETG clear, though other materials have similar symptoms.

 

 

[gr5 2,330]

It's because the glass isn't flat.  We are talking about an error less than 0.1mm in the glass.  This glass is tempered glass and the way it's made it tends to be higher down the center.  Like a mountain ridge running from the rear to the front of the bed.  But the shape could be different than that.  The leveling is only done on 3 points where the 3 screws are so you end up with nicely leveled in the front corners and rear center but the rear 2 corners tend to be low.  It helps to print parts in the very center or in the front half.  Usually.  But again, the glass isn't flat.  It's usually thicker in the middle.

 

The S3,S5,S7 printers do multi-point leveling (not just 3 points) so it compensates for this.  But you have a UM3 it sounds like.

 

What's the problem anyway?  After printing many layers, does anyone care?  Or do you need the center of the bottom of your part to be flat with the corners of the bottom of your print within better than 0.1mm?  I don't think you are going to get 0.1mm accuracies on the whole bottom of your part but, or are you just concerned that the first layer looks bad before it is covered up?  Once it is covered by the second layer, it looks fine, right?  Or are you printing 1 layer parts?  I've printed some of those.  Basically airplane toys.

[fvarnell 0]

Hello. Thanks for the reply. I finally got past this problem but may still have an auto-leveling problem. My glass is very flat. I used a steel ruler and a feeler gauge with both cold and hot build plate, so I don't think that is the issue. But it got me thinking about if the plate was actually level as the problem was worse toward the right rear. I have always had auto leveling set to always. What I did was get it as level as possible that way, then turned off auto level and manually adjusted the plate until I got even first layers across the build plate. 

As far as "what is the problem" question. I sometimes make things where the bottom layer is the most visible. For example making a box top (in this case clear PETG). The box top is really the face that is on the build plate glass. 

I still may have an auto leveling problem even though there aren't any error messages. I don't really know how to troubleshoot that and could not find any info on line. oh, and yes it's a UM3.