Has anyone figured out the best fan settings for the precision airflow ducts?

I printed the second version of the precision airflow ducts that R3D posted on Thingiverse and as suggested lowered my fan speeds at the beginning of the print to 0%, set to ramp up to max at 10mm of height. I'm not sure that really did much, as even a modest overhang looks like garbage. I've attached images of two different tests; the half-done benchy was done with the ducts installed and the above mentioned fan settings, and the completed benchy was done without the ducts with standard settings.

I'm going to do more testing to find the sweet spot, including potentially only using one duct. But before I did I wanted to cast a net out to see if anyone had tread this path before me. Do you use the ducts? What fan settings do you use?

 

So that's interesting; I never considered the output consistencies from fan to fan to be a variable. I wish I had a semi-accurate way of measuring the fan output. I guess I could turn the hotend up as high as it will go, activate the fan for 1 minute, and measure how many degrees the hotend dropped in that time. That would at least give us a repeatable way to see how strong our individual fans are. The fact that one fan is considerably farther away from the nozzle than the other complicates things though.

The funny thing is I don't remember "too much ventilation" even being a thing with the R1. I even ran a centrifugal fan with insane output for awhile and it worked great.

I am running a test benchy now with only the left duct installed and standard cooling settings. I'll run variations until I get an acceptable result on what is not even that difficult of a print, then pick an actual overhang benchmark design and further refine. I'll post my progress as I make it.

 

So I think I got it down, at least for my printer. The settings I'm using in Cura for Robo are:

Fan Speed: 75%
Initial Fan Speed: 40%
Regular Fan Speed at Height: 5mm

That seems to work really well, even small 90º overhangs print pretty damn well. It's nothing like my R1+, which can print the gnarliest overhangs I've ever seen before. But still.

Now I'm having (or I guess realizing) this obnoxious mis-alignment issue. See the attached image. On all of my prints this happens at least once, sometimes more than once. I'm going to give the rods a good cleaning/lubing to see if that fixes the problem.

Also, does anyone have any idea what the heck happened with the top arrow in the image? I've never seen this in a print before or since. Filament issue perhaps?