I’m running into what I think might be hot spots on my build plate and wanted to get the community’s input. Today was the first time I could clearly see where the issue might be happening.
My setup:
0.2mm stainless steel nozzle
0.2mm layer height
PETG (SUNLU brand - been using it forever without issues)
Engineering plate with BambuLab liquid glue for adhesion
Build plate: 70°C
Nozzle: 255°C
I have 1624 hours on the printer
The problem: I’m getting inconsistent adhesion in specific spots that seem to line up with where I suspect heat elements are underneath the build plate. The main area I can clearly see is (see attached image), and I suspect there’s another spot on the left side near the center that’s doing the same thing.
Also, using the BambuLab liquid glue and I’m getting these little spots that seem like they are boiling up. The adhesion works perfectly everywhere else, which makes me think it’s
I’ve attached an image showing the problem area - you can see where the adhesion just isn’t working like it should in that one spot while the rest of the print is fine.
My questions:
Does this look like a hot spot issue to you guys?
Can the build plate or heating element be replaced? I looked through the spare parts but didn’t see anything listed.
If it can be replaced, how complicated is the process?
I’ve got a long print coming up so I’m trying to figure out if this is something I need to address first or if there are workarounds I should try.
First question: did you heat-soak the bed? Without it, you’ll get temperature gradients across the build surface. Bring the bed to target temp and hold it for 15–30 minutes to equalize. Some materials don’t care; others are very picky.
Also note that an overheated bed can reduce adhesion once the part starts shrinking. Rule of thumb: use the lowest bed temperature that still gives a reliable first layer and no other issues. For reference, on my carbon-fiber plate I run ~80 °C for PETG-CF and ~70 °C for PLA Basic—but the right numbers depend on your plate’s thermal behavior and coating.
Prove your theory by reducing the bed temp to see if that problem area behavior changes.
I’d add that a 0.2mm nozzle with a 0.2mm layer height seems like it ought to be a problem. You want the extruded plastic to get squashed down on to the underlying layer. With 0.2mm height and a 0.2mm extrusion you’re squirting out a thread that basically just barely rests on the surface below.
As a general rule, you want layer height to be no greater than 50% of the nozzle width. If that area of the print bed is just slightly lower than the rest of the plate, and the location is between where the printer probes when doing bed leveling, the 0.2mm layer height is going to mean the first layer is air printing.
As discussed: with a 0.2 mm nozzle, 0.12 mm is about the practical upper limit for layer height. We use 0.2 mm nozzles for fine detail; at 0.20 mm layer height you lose that advantage, so it’s not an optimal choice anyway.
Proven layer heights for a 0.2 mm nozzle
0.06 mm — maximum detail and smooth curves.
0.08 mm — best quality/time balance for clean surfaces (recommended).
0.10 mm — a bit faster, slight layer texture visible.
Help, I’ve had so much success with my 1 & only XC/40 Engineering plate I want another 1!
Is it possible to still obtain the originals ? I’m not interested in sticking anything to anything else or any mods, thankyou. I always print in ASA & like a smooth finish. Thanks again.
