From this forum it appears they can but it seems to be inconsistent for some.
this post was submitted on 20 Jun 2023
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Yeah it's fine with pei and it will never get as flat as glass.
Me reading this as someone who just ditched their glass bed because of how warped it was. 🙃
Does the variance return to normal if you switch back to the glass plate? If you probe multiple times on the same spot, do you still get large variance?
Yes to both.
If you press down on the PEI/steel sheet manually, does it look like it's flexing or does it feel stable? When you switched from glass to steel+PEI, did you put an adhesive magnet sheet on the print carriage, or are you using some other method to hold the print surface in place? Just found a post on reddit where someone discovered that their build plate only sticks to the magnetic sheet when they rotate the plate 90 degrees, so perhaps that's worth a try.
Nah it rock solid. The variance come from the texture itself.
Not doubting you, but I can't think of a logical reason for why it would be like that. The probe pin shouldn't push down hard enough to be able to deform the PEI
Perhaps as a workaround you could configure the firmware to probe each spot 3 times and average the result, if you don't mind the extra time levelling would take?
I meant the probe is deflected by the texture. Taking multiple sample is what I'm doing, yes. It take at least 5 samples for it to be reasonably smooth, which is why I'm asking other experience.
You mean you think the probe slides off the bumps in the texture? I think the probe should be stiff and light enough to not do that, but perhaps you could've been unlucky if it's a clone not from a well known brand (e.g. Trianglelabs.. even Creality's probe's are supposed to be quite good afaik)
Yes. I'm certain it is a build quality problem. The probe is just plastic and by design hang freely. Even a steel rod with bearing can easily be deflected by a few tens of micron.
I use marlin UBL with a bl touch. On textured sheet. The first thing is to recognize it’s supposed to have that variance.
I found that increasing the first layer extrusion width (140%, normally I’m at 110% unless I need a strong and ugly part,) and juicing the extrusion multiplier slightly helped.
My calibration process for z offset was:
- set z off set to zero,
-turn off software endsroos. (M211 s0; use s1 to turn them back on. This allows you to go negative positions.) - move the nozzle to 0,0,0 and slide down carefully. I use the smallest feeler gauge I’ve got to test contact.
Then I probe the mesh and save it to the board. (And recall it on the print start gcode and do a 3x3 probe to tilt the mesh into position.)
What I have found is that it slides a bit with the magnetic base- especially on heavy/fast prints invalidating the mesh.
Printer: creality ender 3 pro
sensor: CR-touch (bl touch but creality's with metal brackets for easy install)
bed: creality PEI double sided bed
hotend: creality spider 3.0
firmware: custom marlin 2.0 fw
filament I use most often: atomic filament ABS
creality bag enclosure: yes
Sure does work... But I have babystepping on (Marlin), and adjusted babystepping by coding in a 30x30x5 block with 8 skirt loops 6mm away. The babystepping in this case is to adjust the Z offset, which it does so live.
I was able to get it tuned in so that all prints just apply beautifully.
Maybe clarify what you mean by variance - Samples in the same spot vs variance of min/max points? Temp can change things, are you keeping it constant between measurements and letting the bed heat soak at all? How does the first layer look? If it's consistent you may be over thinking it
I’ve had no issues using the bl touch on a textured bed up to this point, and I’ve been using mine in combination for about 18 months. The bed texture shouldn’t be significant enough if your z offset is appropriately dialed in.
which make my bed mesh all wobbly.
How are you checking your variance? Plugin on Octoprint or another way?
I'm I suppose to remove the steel plate when making the bed mesh? Do you home Z with a probe with this setup?
No, you should be running your bed mesh in whatever configuration you will be printing with. So if you're about to print with your PEI sheet, run the bed mesh with the pei sheet installed. I have my start gcode set up to do run a bed mesh befre every print, if you're interested I can help you with that.
The weirdest thing is, despite all this all my prints adhere completely fine. I guess PEI is just that good.
It's known that the rolled aluminum beds on cheap printers like enders are not flat, they all have waves in them. I'm thinking that the difference your seeing in the bed mesh variance between the glass built plate and the pei build plate is due to the fact that the glass is much flatter. The PEI will conform to some extent to the bed, which in turn will lead to higher variances. The bltouch is there to compensate for those waves in the bed.
What printer are you using? 100 microns variance is probably within the margin of error for your printer's z height. My rule when 3d printing is to not worry about it until something goes wrong.
I build my own printer so worrying about little details is most of the fun. This is not a little detail though. 100 microns is massive. That's half a typical layer height!
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