HELP! New Cast Alum. Bed doesn't seem to AutoMeshLevel

DIY-O-Sphere

You have to enable the compensation by setting the
M376 with tapered height in your config.
https://duet3d.dozuki.com/Wiki/Using_mesh_bed_compensation#Section_Compensation_Taper

Phaedrux

M376 defaults to off, meaning that the compensation is active for the entire height of the print. If you set a taper height with M376 the compensation will start to taper off over that height. Setting it too low can be problematic, but not setting it at all doesn't matter.

Can you check M122 during a print and look for

=== Move ===
DMs created 83, maxWait 1353041ms, bed compensation in use: mesh, comp offset 0.000

If it says none instead of mesh, it means the compensation is being disabled during the print.

Another way to verify if the compensation is working is to try printing with PLA that you know will stick and print a test pattern like this one twice, once with it enabled and again disabled. You should be able to tell pretty quickly if it's working or not.

Also, try upping your bed temps even more. PETG likes a hot bed. Glue stick (to keep it from bonding to me PEI) and 80c work for me.

percar

Are you printing on bare aluminum?
If you are that may be a problem try covering with Kapton tape and using hair spray it works wonders
I too tried cast aluminum plate with the same result I ended up switching to Borosilicate glass and my problems with leveling went away

Christockos

@percar No, I'm printing on a spring steel sheet/magnet combo, like a WamBam, but TinyMachines version.

Christockos

@Phaedrux Hey Phaedrux!

This is what I get after a M122
Bed compensation in use: mesh, comp offset 0.000

That's the only Mesh related thing in the report, via typing M122 in console. I assume that's the only way to do it.

So it says it's working. hmmm

Such weird symptoms, I'm baffled.

Thanks,
Chris

Veti

@Christockos said in HELP! New Cast Alum. Bed doesn't seem to AutoMeshLevel:

M305 P1 T100000 B3950 R2200 C7.06e-8 ; set thermistor + ADC parameters for heater 1 HOTEND

that is an incorrect setting. what thermistor are you using?

Phaedrux

bedlevel_nozzle_0.4_200x200-0.3-0.8.stl

Try a test print like this with PLA twice. Once with G29 S1 (mesh enabled) and again with G29 S2 (mesh disabled). It should be fairly obvious if it's actually taking effect.

Christockos

@Veti I'm using a Semitec104gt-2. I have a Volcano Hot End.

mendenmh

My experience with PETG is that it likes the bed quite hot, to get good adhesion. I have an Ultrabase, which has 3mm glass on the aluminum base. The temperature is measured at the aluminum layer. A rough estimate of the heat flux gives me about 10 degrees lower at the surface of the glass than at the thermistor. If I set the thermistor to 90C, so the glass is about 80C, PETG sticks quite nicely. Much lower than that, and its adhesion isn't too good. One characteristic of PETG is that you don't want the nozzle too close to the bed on the first layer. If the nozzle is close, the PETG pulls itself along off the bed. It likes a bit of a drop height, as opposed to most filaments which like a lot of squish.

Also, I print PETG at a fairly high nozzle temperature, 250C. I am using a PT1000 sensor, so I am fairly confident of this number. The viscosity is fairly low when it is this hot, so one can print fairly fast (240um layers at 90mm/sec with a Hemera extruder and 0.4mm nozzle).

Veti

@Christockos

that would be M305 P1 T100000 B4725 R2200 C7.06e-8 ;

theruttmeister

@Christockos said in HELP! New Cast Alum. Bed doesn't seem to AutoMeshLevel:

So I did another major upgrade.
Aluminum cast tooling plate (10mm) with a silicone heater

I thought this would solve my problem(s), but it’s still a nightmare. First off, I thought this cast plate would be FLAT. Here’s my height map:

That map looks good, although once you upgrade the bed to something like 10mm of I assume MIC6... don't forget that the rest of your machine might not be square or true. That curve in the bed could very easily be droop in the gantry. Or your bed has no support in the center.

But printing PET on PEI should be an absolute breeze. Those two polymers will quite happily weld together and be almost impossible to remove.

I normally run CF-PET on PEI at ~235C with the bed at ~110C. Sticks like crazy.
Assuming its not something silly like tiny extrusion widths or some other slicing problem... I'd suspect contamination of the bed. Its easy to get stuff on the bed that will form a film that prevents the polymer from sticking down.
I have a spray bottle of 100% ethanol (but any alcohol works) that I use to clean the bed any time I have an issue.
Windex actually prevents things sticking (at least with blue tape...) so be aware that 'cleaning' sprays might actually make things worse.

PET is actually very easy to get to stick. On bare glass you should be able to get it to permanently weld on so strongly you'll break the glass trying to get it off. PEI is very similar. I would only use glue to protect the print surface!

Christockos

@Veti said in HELP! New Cast Alum. Bed doesn't seem to AutoMeshLevel:

M305 P1 T100000 B4725 R2200 C7.06e-8

Much Thanks!

o_lampe

One thing not mentioned by anyone is the G31 probe offset. Are you sure it's OK?

Christockos

@theruttmeister Well, I'd become so accustomed to 24V DC heating my bed (88°C max, even in a heated enclosure) that cranking it for PETG had never occurred to me. Well, making my PETG prints stick is no longer a problem, thanks to the 110V AC silicone heater. Amazing! Thanks Ruttmeister and everyone else.

Christockos

@o_lampe It's fine. Thanks for asking. You rule!

Christockos

@mendenmh Thanks for sharing. I've tried 90C and even 100C. Both work swimmingly.

Christockos

So, turns out I had a faulty cooling fan (amongst a bunch of other things I went over, disassembling my hot end/extruder and cleaning, checking alignment, etc.). Turns out my bed is just fine and mesh leveling works as it should. Lots of other little adjustments, fixes and the aforementioned cooling fan and I'm back in business.

Thanks so much everybody! I love my machines with Duets running them. The great community of knowledgeable and generous geniuses make my love of the Duet even stronger and more enduring.

Rock on!
Chris