This is a solution, finally, to those nasty non-bridging bridges.
I’m sure I’m not the first one to figure this out, but here it is, my elegant and exquisitely (if not humbly) conveyed compilation of conclusive conclusions.
Welp.
I think it is about time for a definitive resolution. I’m happy with this, maybe you will be too.
Try the following:
- Set Quality>Briding>Bridge counterbore holes = “None” (unless you want it for some other personal reason)
- Speed>Overhang Speed>
Slow down for overhangs [checked]
Slow down for curled perimeters [checked]
Overhang speed
– (10%, 25%) = 0 (default, this sets full print speed for small overhangs between 10%-25%
– (25%, 50%) = 50 → Tinker with this as desired to slow down those overhangs which typically don’t require supports
– (50%, 75%) = 30 → (default, this is a slower than bridging print speed for extreme overhangs which are typically supported)
*-- (75%, 100%) = 10 → 50 (or your preferred bridging speed. THIS is our sucker right here which super slows down our stretches being conditionally coded as non-bridge overhangs, and which makes for droopy bridges. I think the slicers code them for low and slow under the assumption that ALL floating sections within some discreet parameter, which don’t convert to “bridging,” will be otherwise manually supported, and the long straight parts should print very slow for maximum quality and/or to avoid unintended interaction with support interface… which doesn’t make sense to me, but okay.)
Bridge
– (External) = 50 (default, or whatever you prefer your bridging speed to be)
– (Internal) = 150% (default, or whatever you prefer your bridging speed to be)
Hint:
If you want to check your speeds on the fly and tune things based on overhang, make copies of multiple objects, adjust parameters per object, slice, change “color scheme” from Line Type to Speed and figure out what parts are falling in which speed/bridging/overhang parameters in your settings based on the color/speed assigned to that particular layer/part/area.
Below is me tinkering with the typical unsupported overhang threshold. Usually set to 50 by default (overhangs 25% - 50%)
(Pictures in the GitHub comment)
^^^Honestly I didn’t see really any difference in the 30 vs 50 for the [25%, 50%] overhang on the tail, so slowing down really didn’t “improve” those 45° angle overhangs, but neither did it detract from them - however -
That one last nasty droopy bit right in the middle between the legs, which shows in my sliced photos as an off-color (darker/slower) line right down the middle, DOES go away if you set all of the settings to 50 for overhangs from 25% to 100%:
– (10%, 25%) = 0 (default – full print speed)
– (25%, 50%) = 50
– (50%, 75%) = 30 → 50
– (75%, 100%) = 10 → 50
et voila.
Happy printing. And remember, that top one is those near vertical overhangs - my default TPU profile was set to 60 mm/s for that one, I’m curious and excited to see what making these changes will do to affect supported and unsupported printing in all manner of filaments!
PS: Dont judge me on the bubblegum pink. I inherited a fabulous array of random 1-2m long samples of dozens of colors. My only regret is not realizing a long time ago that the secret to printing with TERRIBLE old dry PLA filament without it curling up is
- Print a diverter for your aux fan which aims it upward at least 45°, so it doesnt actually hit your print but provides circulation
- Open/Prop the Top - because I’m one of those poor suckers who, if I close my machine entirely, it will IMMEDIATELY heat creep 100% of the time.
- CLOSE the door - keep the fresh air from flooding in, but the mild circulation caused by the diverted aux fan and the open lid lets out any excessive heat, which prevents heat creep.
The diverted fan keeps the air circulating with the top open to preclude heat creep, but without directly cooling your print, and keeping the door closed keeps the chamber warm which reduces the cooling gradient between the freshly printed upper layers vs. the consistently bed-heated bottom layer which, even on small footprint items, if printed with garbage filament, will almost ALWAYS curl and get all wonky, with laughably no help from Rafts/Brims whatsoever because that old filament wants to WARP and there is no physical way to stop it!! … except to reduce the thermal psychics which make it warp in the first place. Boom.
Oh, and this works as a panic fix if your prints ever start grinding at the corners (a sign your corners are starting to lift, that thing when the infill starts getting bumpy and/or stringing, and then catastrophically fails from impact). You can boop the door shut and kick the aux fan on (PRINT THE STUPID DIVERTER) and it’ll almost immediately stop grinding and go back to printing like normal again. I’d rather risk a heat creep clog than a busted printer from an impact and/or due to a print curling up and releasing mid operation.
https://makerworld.com/en/models/809285-auxiliary-fan-defusor-45-degrees-no-fins#profileId-750296