Sudden ABS Nonadherence

I have been printing with the Lulzbot natural ABS 3mm filament for better than a year on my Mini and been getting very satisfactory results with good PEI adhesion and no warping. I use the standard Cura parameters and have an enclosure that keeps the inside temperature just below 100F. Suddenly I can’t make a print stick to the PEI.

Last weekend I used some scraps of older filament with good results. Then I switched to a new roll of filament and nothing will stick. I just tried a second new roll of filament and no joy.

Is it possible I received bad filament?

I think I figured out the problem. My bed is not heating. How do you troubleshoot this problem?

While it could be bad fillament, unless you ordered the cheap crap from china, it’s probably a smaller diameter than you had before, so its underextruding and not sticking. Measure the fillament diameter with calipers and compare it against your other stuff. If it is indeed smaller, adjust the fillament setting in your slicing software to match. Most of them are set to 2.85mm by default.

Also check for air bubbles in your bed between the PEI and the glass.

That would do it. With a mini bed failing to heat issues are usually related to the bed cable assembly. Check the 15 amp automotive fuse on the rambo board first though as it is the inexpensive fix. Also check all the leads and plugs. Newer minis use a different cable setup. If you are under warranty call support. If you aren’t, look at sourcing a new harness . it’s also possible that it is the heater itself, but that is very rare and unlikely.

All the fuses are good both visually and by continuity check.

Next step then is to check the harness wires and the bed itself for continuity. usually the break is in the harness when that issue occurs. If it all checks out, it’s either a board glitch or a software issue. The bed is one loop, the thermistor is another loop and eaxh of the individual harness wires is straight through. You may want to avoid continuity checking the thermistor leads as they can be a bit fragile. At very least save them for last.

Thanks, piercet. I changed the heater bed harness and all is well.