It’s the “nozzle” diameter – not the filament diameter.
To check, go into Cura Preferences -> Printers -> pick the printer -> Machine Settings
From there you’ll see a window with two tabs… one is “Printer”, the other is “Hot End” and dual extruder heads have two “Hot End” tabs so you’d need to check each of them.
That tab will have the “Nozzle” diameter. Make sure the nozzle diameter defined matches the nozzle diameter of the toolhead.
If using Cura LulzBot Edition, when you add a machine definition – it asks for both the machine and the print-head. It will define everything correctly based on that head. If you swap heads but don’t update the machine define (or just create a new definition for that alternate head) then you can get wonky print results.
The area of a circle doubles each time it’s size changes by a factor of roughly 1.4x (the actual number is the square root of 2, but 1.4x is close enough). E.g. a .5mm nozzle has double the area vs. a .35mm nozzle and 4x more area than a .25mm nozzle. This means that if the nozzle diameter in Cura is set to a value larger than the actual physical nozzle diameter, you’ll end up with over-extrusion.
You can have first-layer issues based on z-offset value. E.g. if the nozzle is too close to the build plate it can squish the filament fairly wide and end up with a poor quality result. This would happen even if all other settings (e-steps, nozzle diameters, etc.) were all correct. If you post a photo of what your printer is doing, the community might be able to take some guesses as to what is happening.
The FlexDually does use 0.6mm nozzles (assuming they haven’t been changed).
Thanks for posting those photos … it certainly looks like the nozzles are heavily over-extruding.
Another place to check is in the Cura “Prepare” menu. Make sure you’ve selected “Custom” (in the Print Setup category) and then scroll down to find the “Material” section. You’ll find a setting for “Flow”. While most materials tend to use 100% as the flow rate, sometimes it helps to adjust this. My default profile for NinjaFlex TPU sets the flow to 110% (TPU has a reputation for being “stringy” and doesn’t respond very well to retractions … so if you see a bit of stringing it’s probably ok). But if the Flow setting is way out of whack (set well above 100%) then it might explain the over-extrusion.
It might also be worth tracing through the setup steps to make sure nothing was missed.
I was just reading on another site that some of the shell settings could cause the kinds of issues that I am having. I have checked and double checked every suggestion Tim has given me so far. Is there anything I should be looking for with shell settings?
I don’t know how any setting could be so screwed up. I have a new download of Cura, and I’ve reverted everything to default settings several times.