Supports? I don’t need no stinkin’ supports! 
Inside of the box was not cosmetic, so suggested to the customer that printing without supports would be faster and cost less. Warned them that it would be really stringy / droopy because of sagging bridges.
Did not expect it to turn out this well! (Heavily modified @Printrbot Simple Maker edition - the laser cut plywood and fishing lines are loosely assembled on a museum shelf elsewhere in my shop).
I’ve never devoted much time to optimizing this with speed adjustments, but have occasionally stumbled onto kind glowingly good results on huge bridges. Fun!
Brook
Nice! Once I get my printer up and running, I’m going to have to try some bridging.
Nice! The part cooling fans effectiveness plays a big part in this being possible. What settings are you using?
What settings are you using? extra supports are my best friends
KISSlicer 1.5 (Linux32 Aug 4/16)
0.2mm layer height, 0.4mm width
10% infill, 0.5 “Depth”
~45mm/S, max 8cm^3, 1.6mm Prime, 1.5mm Suck
208C (PLA)
Fan 70% (blower through an awful home designed nozzle)
Interesting - just notice that KISSlicer predicted a 9hr 6.3minute print time, and RepetierHost reported a 9hr 6.5minute print time.
Very similar to the speed I bridge at. I get my best bridges at 0.1mm layers and full 100% fan. Cools really fast.
If your interested I can point you to a high efficiency part cooling fan duct (could be adapted to your printer) and a bridging and overhang test part to see the results.
Sure @Jeff_Parish - always interested in better designs.
At present I have to throttle back the fan otherwise the hot-end struggles to maintain temperature.
@Alex_Wiebe See the link to the general design idea below.
The idea is to focus the cooling air stream right at the tip of the nozzle in a horizontal direction but clear the bed and printed part. The outlet is a small area about 5mm to either side of the tip with a dual direction opening. The bottom half is a straight out horizontal flow area and the upper half is an angled surface pointing at the nozzle tip. The combined stream blows horizontally across the surface of the model right at the tip of the nozzle. This requires a high pressure fan so the air can be forced through a restricted area without back flowing. By focusing right at the nozzle tip the heating element is not affected by the air stream which allows it to be stable even at 100% cooling. The air flow also does not create a large turbulence area behind the nozzle allowing better more even cooling on the back side even with the air stream blowing all the heat away in one direction.
I can get crazy overhangs, long bridges, and rarely use support material. When you check out the test object notice the 5mm by 3mm horizontal cantilever. It was flat by layer 4 using .1mm layer thickness. It’s very satisfying to watch a 50+mm hole get bridged over and filled in effortlessly. Ironically the part cooling fan itself does require supports.
Your part cooling duct looks pretty focused already but you might be creating a turbulent air zone right under the assembly which is affecting your temperature stability. Is it on Thingiverse? What does the exit opening around the nozzle look like? What kind of fan are you using? Centrifugal (hamster cage) or axial like your extruder cooling fan? At any rate the bridging you achieved is impressive.
In the end I wholeheartedly agree with your original statement.
Supports? I don’t need no stinkin’ supports!
Nicely done!
Uses a 50mm centrifugal fan.
Bridge test part
My cooling nozzle is a nasty melding of @Printrbot 's cooling nozzle (https://www.youmagine.com/designs/printrbot-blower-fan-mounts) and the nozzle from iamjonlawnrence’s axis upgrade (https://www.thingiverse.com/thing:242185/#files). Hacking STL files together is not my gifting…
Actually just spotted this: Printrbot Simple 300mm No Sag Fan Duct by iamjonlawrence - Thingiverse
Might work…
Eliminate the smaller of the outlets and extend the other opening straight out about 5mm to produce horizontal flow and you could make it better. I can help with hacking STL files if you need it.
Thanks - will keep you mind! I’m not going to be able to do much probably for a few days - looking forward to next week when I’ll have more tinkering time!
