New i3V owner: A few beginner questions

[printbus]

I've only got about a month more experience than you, so bear that in mind. Note that while the overall print speed may be 100%, Slic3r applies about 10 different speeds factored off that, depending on what is being printed (perimeter, infill, etc.). If you haven't seen them, these Slic3r settings are visible in the Speed section of the Print Settings screen.

One thing that was enlightening for me was to feed the gcode through a viewer like gcode.ws. You probably can with other viewers too, but with gcode.ws, you can click on layer info and then walk through the print layer by layer, observing how different speeds will be applied to different parts of the print. I would compare the print speed being applied to the top solid layers with what is being used elsewhere, since that seems to be printing OK for you.

Reducing 3mm filament to the 0.40 mm tip is a pretty good reduction (3mm has almost 3x the surface area as 1.75mm filament) and it could be you're just not melting enough fast enough. You might need a higher temp (210 could be low anyway) and/or a slower "top solid infill" speed in Slic3r. Or maybe even a higher drive adjustment for the extruder stepper motor driver to maintain the pressure at the nozzle during high flow volumes.

EDIT: Unless it has changed since I archived the config files, the MakerFarm config file for 3mm PLA on the 0.4mm hex hot end will have Slic3r print the top solid layers at 100 mm/sec. It'll print perimeters at 75 mm/sec, and the external perimeter wall at 70% of the other perimeters, or 52.5mm/sec. So, the external perimeter walls you can see are printed at about half the speed of the top solid layers. That could be part of the reason why the rest of the print looks OK, at least on the outside.

EDIT #2: Well, there is a another filament cooling setting in Slic3r that will slow the print down if the time spent on a layer is less than a default of 30 seconds. That should be the case for at least the knob, so the above numbers may not apply. Just another reason why I like to look in a gcode viewer before I print to see what the printer will actually be doing. Regardless, the config file will still have the top solid infill printed faster than the perimeter shells.