Ugh at 120 micron the not so difficult overhang became so hard to get it right. Not even sure if more powerful fan would help?
More cooling would definitely help. These overhangs are completely possible to print, they’re just very difficult to tune right at these lower layer heights.
Overhangs should be EASIER at lower layer heights. More of the plastic in each strand is positioned over the previous layer.
If it’s not clear, imagine 0.2mm height by 0.4mm width. A 45 degree overhang will place half of each perimeter strand over air. (0.2mm rise at 45 degrees means 0.2mm overhang.) But a 0.1mm layer height at 45 degree overhang means only 0.1mm overhang, which should be very easy to print.
I really think you need more cooling, or better-oriented airflow, or perhaps even higher nozzle speed. Overhangs don’t just need more initial cooling to freeze solid fast… they also can’t absorb as much heat from nozzle dwell and the next layer pass without re-melting, because there isn’t a lot of plastic there to sink the excess heat into.
@Ryan_Carlyle but here’s the problem: heat. As the hot end is passing by laying down the next layer, the heat coming from that and the heat from the new layer is enough to easily melt and warp the previous lawyer. With less mass in the layer it lacks structural integrity and causes it to collapse under its weight. Alternatively, if you print that same overhang at a higher layer height, the heat from the previous layer doesn’t permiate through the previous layer enough to cause that warping as much. Think of it like talking a lighter to a soda bottle. The body of the bottle will warp easily with the heat, yet the neck where the threading is will stay mostly in tact because there’s more plastic there and therefore needs more heat and/or longer exposure to that hear to melt.
Have you tried adding more perimeters? It helps keep the structural integrity when the hot end tries to melt previous layers and perimeters
@Steve_Wood_Gyrobot why would perimeters help? The base looks perfect to me and it’s not an adhesion issue.
@David_McGuigan Perimeters are nothing to do with the base, are you thinking of “brim”? Perimeters (and loops) are what define the vertical walls of a print.
@Steve_Wood_Gyrobot apologies. I guess it depends which slicer you are using. I thought that was shell thickness? I agree that adding more shell/perimeters may provide a bit more support (and some heat sink).
try craft were with free custom supports win 7 link: https://craftware.craftunique.com/download/win/CraftWare_1.14_and_CraftPrint_1.04
@David_McGuigan Yeah, I think Cura calls it she’ll thickness whereas most people call it perimiters.
Thanks, @Andrew1 . I was looking to try a different slicer.
@_Spice Lower layer heights ALSO help with heat-shedding and remelting, because each new strand has less hot molten plastic. Half the layer height = half the heat that must be shed for the layer to cool. Plus shorter strands have a higher surface area : volume ratio, which means airflow cools them more effectively.
The amount of already-printed plastic sinking heat from the new strand doesn’t change with layer height. That’s entirely based on print geometry and perimeter count. But lower layer heights reduce the overhang severity AND mean less heat being pumped into the print per pass.
The ONLY way low layer heights can make overhangs worse is if you’re printing too slow, and the nozzle-dwell is reheating the print.
I would add a delay so that there’s a minimum amount of time per layer. In S3D you can select the option for it to adjust the print speed to slow it down. to meet a minimum layer time.
@Tim_Sills If the issue is nozzle dwell from slow printing, minimum layer time won’t help. You need an effective cooling fan for slowing down to be useful.
Thanks all good point. Will look into playing with cooling fan upgrade first then play with slicing setting
Got virtual image @shot?