What are the tricks to making perfect overhangs and bridges? I otherwise get almost perfect prints, if not for saggy overhangs. And I stay away from bridges for the same reason. I do have 2 cooling fans in front and back of the head, but w/o shrouds/ducts. What else can I play with - temperature, speed, etc. - to improve it? This is on RoBo 3D with E3D hotend printing PLA at 200C. Thanks.
Try printing bridges faster and with reduced extrusion (90%). You may also need to drop your extrusion temperature. 200C seems high for this on PLA, but I don’t have much experience there.
Nylon bridges like a dream for me. But Nylon is stretchy and sticky.
Key to bridges are to go really slow (10-15mms) lower temp and less extrusion. (I usually use about 0.85) You can use the reprap calculator to calculate the correct value. http://nathan7.eu/stuff/RepRapCalculator/RepRapCalculator.html#PrintSetup
The finer you go with layer height, the better overhangs you get on top of what has been already suggested.
@ThantiK assuming you are overhanging and not truly bridging over a large gap. I guess support is needed then on pla, huh ?
Forgot to mention that a fan blowing on the print is crucial for PLA bridges and overhangs.
@Phil_Hord , nah. I just did some parts for my ingentis at 0.1mm layer height where there were 10-15 layers easy that were very close to 90 degrees out into the middle of nowhere.
Yet go too low and your bridges will tear.
For overhangs, I’ve found that slightly over-extruding (instead of under-extruding, which makes other parts of the print nicer) will allow you to do the wildest slopes.
I’m printing at 0.2mm layers, using the default setting to go fast for bridges. I’ll try other suggestions. Thanks.
There are two completely opposite schools of thought for bridging speed, both of which are mentioned above, high-speed and low speed. I’m in the second camp. Either way, reducing extrusion is usually a good idea, though it may go the other way for extremely thin layer heights.
I saw a couple of interesting posts on Reddit about this the other day that may be of interest:
Certainly shows what’s possible…