Large PLA print lifting bed off of magnetic sheet

[azCubs76]

These latest pics look like extrusion/speed issues to me. I’ve settled on reducing the speed on all surfaces to ~50mm/s regardless of filament type and all my prints come out perfect now. Under the speed tab I set First Layer, First Layer infill, Outer wall and Top surface all to 35-50mm/s. On that print it will hardly have any affect on overall print time too. I use the BBL Textured PEI plate at 60ºC for PLA and keep the door closed.

This may be a good candidate for PLA-CF. I’ve been amazed at how perfect that filament comes out in both surface quality and dimensional accuracy. It’s really rigid though.

[RocketSled]

the lettering doesn’t seem to come out as clearly when printing text flush face down versus printing a couple of layers on top

Letter-side-down print. While there are a few issues with it, I made no effort to tune for the filament and I needed the build plate where the printer does its advance calibration so I turned that off, too. Loaded the AMS with Inland, picked the default for ASA generic and had at it. I’m underextruding a little, and I’m confused as to why the gyroid infill pattern is visible given there are 4 layers of solid print on the build plate before infill started. But for my first-ever multi-color print using all defaults for ASA and no calibration, I think the results were pretty darn good. And if you zoom in on the lettering, the edges are all nice and sharp. Of course, these letters are about 1" high and yours are smaller, but if you filled those letters with a different color filament they’d probably come out as good or better (if you tuned first) than my example.

[ampster40]

If you are not concerned about the bottom surface, try adding cutouts like these. They’ll remove some of the tension on the bed surface.

[MizuUsagi]

On large parts turn off the AUX fan. Also, with Inland filament I do run it slower. About 15 in flow, and adjust the top layer speed to 100mm. You can also use bed clips but just turning off the aux fan helped a ton with the print shrinking too fast and tacoing the bed.

[p0lrb3ar]

I was having issues printing an enclosure, lots of warping occurred with the AUX fan on or off. I have been using Overture PLA for most of my prints, and may not have the PLA settings tuned quite right yet. Overture filament prints have, otherwise, been coming out very nicely with almost no layer issues.

I found some clip-on bed clamps from printables.com that helped prevent the PEI bed from releasing during warping. https://www.printables.com/model/321213-bambulab-x1-bedclamps-for-big-prints. They helped me get past a couple of large print issues without worrying about the filament tuning.

I’ll be trying my enclosure again with Bambu filament to see if it is a tuning and learning issue.

[vonwilbur]

I followed this advice and turned off the aux fan entirely to see if that would fix the warping… and it seems to have done it! (I also lowered the flow rate to 15mm3/s and that seems to have also fixed the extrusion issue. I could probably bump this up higher to run faster but that’ll require some more experimentation.) Note that this wasn’t a textbook full bed print but there was 1-2" from each side of the bed which would have previously warped .

As you can see from the above image there are no more visual issues at the corners. The bottom of the print is also very flat unlike before. Strangely there seems to be a bit of underextrusion at the center (warped bed possibly?) You can also see the infill through the top layers that might be able to be fixed by just adding more top layers (this print has 3.)

I worry that for thicker full bed prints this fix may not be sufficient in limiting the internal stresses but for now this seemed to have work.

Overall the changes which made the biggest difference seemed to be:

• Moving from linear infills (grid, cubic etc.) to infills with non straight lines (hex, gyroid)
• Moving to the textured PEI sheet (or possibly raising the temp of the cool plate)
• Turning off the aux fan entirely

Some variables that may or may not make a difference seem to be:

• Volumetric flow rate
• Hotend fan speed

Hopefully this helps others that have the same issue. I’ll update this thread if I have any other information.

[MizuUsagi]

I am seeing some top surface artifacts. In your print profile, go to speed tab and adjust the top surface to about 100. This value is very filament dependent. This should give you a better top surface.

I’ve printed some large objects including several parts that are more than 500g and with these settings it didn’t warp.

This guy is just shy of 2 meters and about 11 spools. I need some better pictures.

[scc]

@vonwilbur

• Moving from linear infills (grid, cubic etc.) to infills with non straight lines (hex, gyroid)

I spent some time printing very large dense prints in PLA. When it comes to parts like that, the internal stresses in the part are so large that it is completely unreasonable to try to improve adhesion - the goal is to reduce internal stresses. The best choice is to sort of “match” the cooled temperature of new layers to the bed temperature. You’re very close to what I ended up finding (and now use) for this type of part. There are two major strategies:

• If you have an X1C and want better overhang quality on your part, keep the aux fan on, but keep the enclosure completely closed during the print (the aux fan will effectively help circulate hotter air to keep the air temperature warm and matched to the cooling PLA. Generally, higher infill parts will require plate temperatures closer to 45C. For extremely large parts like yours getting it correct to a degree or two makes a very visible difference in warp. Cool plate is preferred as it maintains adhesion at lower temperatures.

For PLA, higher temperatures will actually encourage softening of the part during printing, which will lower print quality of bridging (that means top surface quality as well) and overhangs over what your normally expect from an X1C. I find parts that print on PEI temperatures might not warp during print, but once they cool you quickly realize that they have extreme built in stresses. It’s important that the plate/chamber temperature is not just hot enough, but correctly matched.

• For an P1P or open frame printer, it’s much harder to get things right, but your only real option is to disable the fan and do your best with picking a bed temperature.

[scc]

@vonwilbur

Strangely there seems to be a bit of underextrusion at the center (warped bed possibly?)

I’ve been spending a lot of time testing similar prints - what’s going on is because the aux fan is off and the part is so dense, insufficient cooling is causing the bridging that normally occurs between infill and top layers to sag significantly and cause top layer defects. It is worst at the center because that’s where the heat buildup on the part is maximized. I would prefer keeping the aux fan on and using suggestions above (cool plate, lowered bed temperature), but you could try experimenting with higher infill density (which worsens the part temperature even more), slowing down the print to reduce heat buildup, and/or slowing down bridging velocity and increasing top layers (or slowing down top layers)

[Gormeck]

I have add similar issues with a larger print myself, the print is warping and lifting the plate off the magnetic bed running the print obviously , i print this with the stock standard 0.2 profile on a P1P printer, no aux fan, room temperature 22 degrees Celsius, bed 65 degrees Celsius, hot end 220 degrees, no draft in room, windows closed (it’s winter)
I have tried using painter’s tape to hold the plate to the bed, it literally ripped the tape off and still lifted

[Barryg41]

There are multiple threads already addressing this problem.

Just search " plate lifting "

[Rockel83]

I’m having the same issues with my P1S now.

Printed a human sized head yesterday, had to cut it in 2 with the use of connectors, using bambu slicer due to its size.

The first part seemed to have no warping and that it was just straight to bed when finished. But somehow I had my doubts and put on the glass cover of the printer, which should be completely flat. And there was some slight warping visible.

Still had to print the second part, so I was more aware of it now.

It had perfect first layers and all stuck well to the bed (Textured PEI sheet). When it was finished, the borders of the print where attached to the bed and there were no signs of warping at first glance.

I took the printbed with print attached onto out of the printer. And still all was adhered to each other, without signs of warping. Even needed quite some cooling and force to snap the print of the plate.

After did the first test as before, keeping the downsidepart on the glass top, and again visible warping…

When trying to connect the 2 halfs, the joint really looks terrible while it’s not flush…

Warping is only visible on both parts on the length of the print, so from nose to back of the head. There seems to be no warping signs at the short part, from ear to ear.

Feels like a lot of wasted time, energy and effort…

PS, I printed with clear PETG and with the top cover and door open. to prevent heat build up and other problems regarding cooling.