First layer weirdness

So I have a small model (say 1" by 2" and half an inch high), which I’ve sliced with Cura to print in ABS, and need to print it over and over. After some tweaking, I can print them one after another with a fairly high rate of success. As the day warms up and cools down, I tend to adjust the z-offset to keep the bottom of the first layer looking good – close enough to avoid warping but not too close to get squished looking lines on the first layer. Generally the z-offset is somewhere in the 1.85-1.25 range.

In an effort to speed up my process, I’ve tried several times without success to print 2 or 3 of the model at the same time. For reasons unknown, the filament just doesn’t stick well on the first layer and ends up pulling the plastic around the bed and eventually makes a mess. I’ve tried increasing the flow rate on the first level and have cranked the z-offset down past 1.3, but nothing seems to make it stick. I can print one model at a time no problem, but two or more just seems to confound the machine. Suggestions? This is on a lulzbot 6 sliced with Cura 2.6.69 using the IC3D abs profile with minor tweaks.

One thing that I would suggest trying is a bed reconditioning, this will get rid of anything on the PEI sheet that could be inhibiting its adhesive properties as well as add more surface area to the PEI sheet both of which help to improve bed adhesion overall. To recondition your bed get a spray bottle and mix up 1 part alcohol and 9 parts water. Get some 1500 - 2000 grit sandpaper. Get a sanding block. Spray some of the 1:9 mixture on the bed (get it nice and wet. Just make sure that your printer is turned off and unplugged). With the sandpaper on the sanding block, wet sand the entire bed until you see a slight whitish film, then stop. Clean the bed good using the same mixture with a clean cloth. This process will last a good while. I know this sounds a little strange but it does work really well.

It would also be helpful to see some example photos of some good vs bad first layers that you are encountering so we have that to reference.

Thanks for the reply. Very much appreciate it. The heat bed is a week old, due to an unfortunate glitch were the extruder froze and melted a mark in the original. I’m quickly coming to the conclusion that the Cura profile for IC3D ABS is the issue. If I increase the flow on the initial lawyer and slow it down, I can at least get a print – albiet a warped print. With the default settings, I get almost no adhesion at all, even if I smash the extruder into the bed via the z-offset. The gcode that works well was generated in an older version of Cura, and I’ve been using it for months without problems. I just wanted to speed up my process by printing multiple models at once, and that’s when I started having problems. Just to confirm, even when I try to print a single model with the current Cura profile, I get zero adhesion, so the problem is in the profile rather than having anything to so with printing multiple models at once. Curious if anyone else has had issues with the Cura ABS profiles?

I print IC3D ABS from Cura almost exclusively. no issues here. I’ve tweaked default settings though.

here are my general settings:

  • print temp 238
  • bed temp 85 (remove at 50)
  • flow rate 98%
  • speed ~ 30mm/s
  • layer height (typically between .2 / .3)
  • to avoid warping and improve adhesion i nearly always print with a brim
  • infills vary but normally 20%

most other settings are default “standard” cura profile. I’ve tweaked things here and there but the above produces consistent accurate results for IC3D for me.
the default print and bed temp for ABS I’ve always found too hot