Print Keeps Failing on MK4  

Print Keeps Failing on MK4

Hi, 

I'm fairly new to 3D printing, have only had my printer about a month. Thus far I've really liked it, everything has printed fine first time, I've been able to take STL files, load them into Prusa Slicer, export to GCode and print no problems. I've been printing with PETG mostly, but also PLA. 

But I've now run into my first issues, I've got a print that just fails every single time. I'm trying to print the STL files from this repository here:

https://github.com/CodersCafeTech/Emo/tree/main/3D%20Design/STL

Primarily the piece I've had problems with is Base Bottom.stl

I've done what I always do, load it into Prusa Slicer, orient it flat against the print plate in Prusa Slicer, and export to gcode (well, bgcode since the latest update) using the standard built in 0.2mm structural profile and all the default settings for the Mk4, the same settings that have worked for every other print to date.

When the print starts the filament just isn't adhering to the bed very well, if it manages the first circle when it's filling it in some always just doesn't adhere quite right, then as the printer moves past for the next layer it ends up colliding with it with the nozzle until before you know it the nozzle has picked up half the print and has a massive blob of molten filament around it so I stop the print.

I'm using the satin print sheet, I've cleaned with isopropyl wipes (I do this after every single print routinely), I've tried printing other prints with PETG and those work fine still so it's not like something has broken with the printer in general, it's literally just when I try and print these particular STL files after converting to gcode with the default settings that it goes wrong. I've subsequently tried printing with and without brim, I've tried slowing down the first layer, and I've subsequently tried adjusting the z height a couple of times but still no luck.

I'd naively assumed if an STL file has a model that's a fairly simplistic shape that using the default settings and export to gcode should be enough, but it seems there's obviously something in my naivety I'm not understanding that can go wrong in the export process to gcode that leads to issues around adhesion etc.

Can anyone give me any hints as to what might be wrong here? Why one set of STL files, relatively simple in form would just suffer issues with bed adhesion when every other print so far - little and large, PLA and PETG, have all worked fine?