Flat prints not filling in right

[Chilly_Vexen]

I’m running into something that’s bugging me. Anytime I print a flat base, it never comes out as a clean, solid layer. Instead I’m seeing these little lines both ways, almost like the nozzle isn’t laying down enough plastic or the paths aren’t overlapping enough. I’ve tried bed leveling a couple times, checked the nozzle, even messed with extrusion settings, but nothing seems to nail it down. It’s not ruining the prints completely, but it looks messy and makes me worry about strength. Anybody else deal with this? Did you solve it with flow calibration, slicer settings, or is this one of those “your printer will just do that” situations?

 

[BazingaBot]

This pattern usually points to under extrusion or low infill overlap, which can happen if the slicer’s “infill/perimeter overlap” or “flow rate” isn’t dialed in correctly. A quick test is to bump overlap up by 2–3% or run an extrusion multiplier calibration cube to see if the lines close up. What slicer are you using right now, Cura, PrusaSlicer, or something else, since the setting names vary slightly between them?

 

[allproto54]

I’m running into something that’s bugging me. Anytime I print a flat base, it never comes out as a clean, solid layer. Instead I’m seeing these little lines both ways, almost like the nozzle isn’t laying down enough plastic or the paths aren’t overlapping enough. I’ve tried bed leveling a couple times, checked the nozzle, even messed with extrusion settings, but nothing seems to nail it down. It’s not ruining the prints completely, but it looks messy and makes me worry about strength. Anybody else deal with this? Did you solve it with flow calibration, slicer settings, or is this one of those “your printer will just do that” situations?

Since you've checked leveling and played with general extrusion, my first guess would be to look closely at your initial layer horizontal expansion and infill overlap percentage in your slicer. If the first layer lines aren't being squished together enough, those microscopic gaps show up, especially on a large flat base. Try a small increase to both of those values, maybe 0.1 mm for expansion and 5% more overlap. Also check your initial layer flow or bottom solid layers flow if your slicer separates them. I agree with @BazingaBot to bumping that up by 2-3% just to be safe.

 

[desmond_88]

Thanks for the help @allproto54 ! I’m still learning 3D printing. Just got my Ender 3 about a month ago and have been making PLA pieces for tabletop games. I saw small gaps on big flat parts and thought maybe my filament or bed heat was the problem.

Just wondering, if I change the flow of the first layer, will it help the print stick better, or just make it look nicer? And with infill overlap, can too much cause bumps or weird shapes on the outside?

 

[allproto54]

Sure, happy to help! Yes, increasing the first layer flow significantly helps with bed adhesion, not just looks. Better flow ensures the filament is squished more effectively into the build surface and against the adjacent lines, which is crucial for sticking power. You're also right to be careful about the infill overlap since too much can push the outer wall outward, causing visible bulges or lines on the side of your print. It's definitely a balancing act! Generally, small incremental changes, like 5-10% are safe to start with. Just make sure you check the outside surface of your print after you make the change!