Trying to print a Lego minifig head (smaller footprint than the bulk of the print) and it has a tendency to blow out the base and sink since the surface area is small. I’ve tried extra infill support and reducing the bed temp a couple hours into the print. Is there another way I could prevent it aside from the obvious split it in two?
Here’s what they look like (yes, lots of trial prints and wasted filament, bear with me!):
From left to right: 1) Perfect print (reduced bed temp two hours in), 2) 110C throughout print, 3) 110C throughout print (although the model was scaled down and material deleted for the cutaway - it merely caused the model to lean towards the heavier non cutaway section), 4) Reduced temp to 75C two hours in (the smaller model caused the print to go quicker than the ‘perfect’ one and hence the temperature reduction was too late - the latent heat in the model was enough to distort the base).
The stock profiles extrude the first layer at 130% or something along those lines to ensure bed adhesion for new users. An advanced user can back that percentage down and eliminate that issue. If the issue occurs only on one side of the print, it’s a bed leveling issue. If you back the first layer down and it is still occuring you may be too close to the bed. For a new design, you can also put a 0.5-1mm chamfer on the bottom of the part to guard against that.
The bed is level, don’t think that’s the issue, neither is the extrusion. I will try the chamfer, but pretty much if I don’t turn off or reduce the bed’s temperatures, the built up heat causes the upper layers to sink into the due to it’s mass, the pressure is increasing the heat within the part. I’ve had no issues if the base is the widest or equal to the widest portion of a part, oh well, more experimentation.
I think the base needs directed cooling to solidify it after it gets pass the increase in diameter for the face TBH.
The extrusion width is set at 125%, I’ll dial it down to 115-120% and see what the result is.
What type of filament and what bed temp? Try reducing bed print after the first 3mm… Maybe the bed is keeping the printed plastic soft.
To keep the part lightweight, try more shells (perimeter and vertical) for strength and less infill. Just enough infill to provide a 5mm grid to support the top of the head. If using S3D, try a second process with a higher infill density for the top.
I’d double check the bed level… and/or make sure the gantry is parallel to the bed.
