Core One : wavy first layer  

RE: Core One : wavy first layer

I have a friend who just got a Core One + and the first layer is awful.  I have done some searching to find out why it isn't squishing enough but all I can find is that it is automatic.  An old thread for the Core One states that there is a "live Z" way to adjust but I cannot find it anywhere.

I was going to post a picture from one of their prints and it looks almost the same as the picture above.

RE: Core One : wavy first layer

Posted by: @vlaine

My first layer used to be perfect, but now it’s wavy regardless of the model, the filament or the plate.  I tested with my 3 plates, I cleaned them again and tested again, I opened a brand new filament.  I could not find a way to tune or recalibrate first layer on the core one.  I readjusted the belt just in case.  I have the latest firmware.  Any idea?

When you say "brand new filament", what kind of filament? I'm assuming PLA? What temperature are your printing it at. I looks like a classic problem of PLA being too soft due to temperatures being too high. Here are some things to check:

• PLA printing too warm in the enclosure / not enough cooling. Is the vent open?
• First layer not bonded well enough in that area. You mentioned cleaning the sheets. How did you clean them?
• Nozzle slightly too low or slightly too much flow, so it drags across the part

RE: Core One : wavy first layer

The brand new filament is a Polyterra matte PLA with the vent open.  I clean my textured sheet with Down Powerwash and my PEI with 99% alcohol.  My nozzle looks worn out so I will check if I have a new one to test.  I dont want to purchase a new one right now because I plan to order the INDX as soin as it’s possible.  Can my nozzle cause the issue?

RE: Core One : wavy first layer

Posted by: @vlaine

Can my nozzle cause the issue?

It can but not as the primary cause. Is the sheet textured by any chance? Also what is the print bed temp? If it's around 60 then it's too high for PLA. 

One thing you can try is set the z-offset start with maybe 0.05mm and keep raising in 0.02mm at a time. 

RE: Core One : wavy first layer

Since my post, I came across this.

Live adjust Z

Live Adjust Z (LoadCell)

The Prusa CORE One, and the Original Prusa MK4/S, MK3.9/S, and XL are equipped with a LoadCell, which will calibrate the first layer automatically.

In case you would still like to fine-tune it, you can long-press the LCD knob while the first layer is printed. The Live Adjust Z will not be saved for the next print in this case. 

You can also tune this value in PrusaSlicer, under >Printers >General >Z offset, where a negative value means a more squished first layer, and vice versa. This value is specific to the G-Code where this value is set. 

This means that if you are having issues with the first layer, you need to find the value and put it into the slicer for future.  

I have read that a bad nozzle can cause issues.  For the cost of a nozzle, is it worth the time and effort to fight it?

RE: Core One : wavy first layer

Issue is fixed and the nozzle WAS the issue, but not the way I thought.  I was about to replace my nozzle when I discovered that the screws were very loose.  I tightened the screws and the next print was perfect.  I think the frequent warming/cooling process makes the screws come loose so check your screws once in a while.  I will from now on.

RE: Core One : wavy first layer

Thermal loosening, that is not uncommon.  Good find.  Check screws on a regular basis.

RE: Core One : wavy first layer

I think the frequent warming/cooling process makes the screws come loose so check your screws once in a while.  I will from now on.

That was also one of the reasons why I replaced those large knurled screws with standard M4 Allen screws. Using a tool to tighten them gives you better control than using just two fingers when you can't get a good grip.