Hi all,
Yesterday I didn’t know what to do and so I printed a test as big as the whole plate of my P1s and 0.2mm high
Surprise: when the Biqu Cryogrip plate is installed the result has a strong underextrusion as shown in the photos…
when the original Textured Pei plate by Bambulab is installed the result is PERFECT and uniform in thickness…
What could be the cause?
Sunlu Black PLA+ 2.0
Same file sliced on BambuStudio
Same filament and settings
Leveling the plate before starting to print
The only thing that changes is that for the Biqu Cryogrip plate I selected the plate (cool plate) in Bambustudio and set it to 40 degrees celsius.
For the Textured PEI Plate by Bambulab I set 55 degrees celsius
I printed twice with the Biqu plate and twice with the Bambulab plate and the result was always the same.
First, kudos to you for knowing how—and then actually performing—a first layer test. Way too many people come here without reading the wiki.
You mentioned you “bed leveled,” but did you do a full calibration from the P1 menu? That process takes about 20–30 minutes.
“Bed leveling” is a poor term, but it’s the one we’re stuck with. What actually happens is more like a bed topography scan. That’s why it takes 20-30 minutes in order to gather all that data. The printer measures multiple points across the bed and stores a topographic map of uneven heights in the firmware, then compensates during printing.
Most of the time, it shouldn’t matter even if one build plate is 2mm off from another—I’ve tested that myself. However, if your heat bed is uneven and the build plate height is right at the edge of tolerance, those two errors can stack and reproduce exactly what you saw in your first layer test.
Thanks,
I had done the total calibration of the P1s, about 26 minutes, a few weeks ago when I replaced the hotend and extruder group.
I did the manual tramming of the bed approximately in December 2024, in fact during the test printing, carefully observing the two front threaded bars of the Z axis, they move very little to compensate…
And this is exactly what I don’t understand, why with the original Bambu plate everything is OK and with the Biqu plate instead not.
Before each test I put the flag on “level the bed” and on “enable Ams”
The Cryogrip plate has thickness irregularities, maybe.
The bed leveling that the printer does, as described above, generates a topographic map of the build plate. Then, when you’re printing, the Z axis is adjusted up or down depending on where the nozzle is relative to the high and low points on the plate. But. If you observe the bed leveling process you’ll see it only touches the build plate in a few specific spots (a 5x5 matrix). The system interpolates the bed height between the points it measures. If the plate’s irregularities are uniform, that interpolation works great. If there’s a lump in the plate between the points that were measured during bed leveling, the system doesn’t see or compensate for it. So when you print, you get areas on the first layer that are much thinner (or thicker) than they’re supposed to be.
To confirm your hypothesis I can try to print from the other side of the plate…
in theory the defective part changes side and (if the plate is deformed) from under extrusion changes to over extrusion. Correct?
Depends on the reason for the irregularity. If the metal plate is deformed, yes. If it’s a thicker area of coating on the side you’re having problems with, no.
This maybe a under-experienced new 3d printer person type statement, and I know it kinda defeats the purpose of the cool plate, but what happens if you print 3 small test patches on the cool plate, bed temp 40, 45, 50?
I hope I understood your question well and I’m not an expert but in theory it shouldn’t change anything. The printer logic should adequately compensate for the different thermal deformation of the bed plate due to the different printing temperature.
Thank you. I had checked (internet search if that can be considered checking) before posting and I did see results that said printing on a cool (temp wise) build plate could result in under extrusion.
Seems like the number of variables (between plates) in this are not that many.
The plates themselves.
Plate properties. How well and evenly they bound to heat bed. Coating. How fast they reach set temperature. Is the plate giving an accurate reading to temp sensors (if there are any).
What temp the printing is being done at.
Any preset differences in the slicer itself if they are specific to plate type. Fan usage.
I look forward to what you come up with and do hope you will post.
For the purposes of testing, the slicer settings remained the same for both types of plates. The only thing I changed was that for the Textured Pei Plate I set it to 55 degrees Celsius, while for the Biqu I set it to 40 degrees Celsius (basically half the suggested range, as you can see from the photo).
I also tried to print the same test on the other side of the plate…
A little better but still areas of under extrusion (sorry for the poor quality of the photo)
Way too many people come here without reading the wiki.
