New i3V owner: A few beginner questions

[printbus]

For grins, and since I've seen the open mesh top on a print as well, I ran some comparison prints of that knob. These may not provide any firm answers for you, but there might be some info of value. I assume this is the knob you started with - http://www.thingiverse.com/thing:221920.

I ran three prints of the knob. The first on the left used Slic3r 0.9.9 and the unmodified MakerFarm config file for 0.4mm hexagon hot end, 1.75mm PLA. White doesn't photo well, but it's the only PLA I currently have. Although not as extensive as on your print, the top layers definitely show the mesh and are not "closed". Watching the print layer by layer, substantial droop was observed when printing bridges at 150mm/Sec as specified by the config file. One such layer is where the knob transitions from being open on the bottom to closed, and the other is just under the logo on the top. For the lower layer where bridge was used, it took several additional layers before the newly applied honeycomb infill seemed to not suffer from it. For the upper layer where bridge was applied, the drooping was substantial enough that the next solid layer also sagged, and the top and final layer therefore didn't have a substantial subsurface to extrude against - hence the stringy and open appearance. More extensive infill or a print cooling fan would probably help here.

The second in the middle used Slic3r 1.1.6 and a custom config file for 0.4mm hexagon hot end, 1.75mm ABS. Version 1.1.6 adds some config parameters beyond v0.9.9. I didn't know what would happen if I used the 0.9.9 config file with it, so when I started using it I recreated new config files for v1.1.6, initially leveraging settings MakerFarm had in the 0.9.9 files. Over time, I've been tweaking many of the print speeds. Right now most more closely follow what is suggested starting here - http://richrap.blogspot.com/2012/01/...tings-and.html than the MakerFarm values. Most significantly, the bridge print speed is considerably slower than 150mm/Sec. Beyond those changes, I now also typically use rectilinear infill at 25% (just works better for me than 20% honeycomb), first layer extrusion width of 250% (my ABS seems to do better with this), and top solid infill extrusion width of 125%. A crosshatch pattern is noticeable on the top layers, but the top is solid.

The third knob on the right also used Slic3r 1.1.6 and a config file identical to that for the ABS knob except that the bed and nozzle temps were set for PLA (70/225 per the MakerFarm suggested settings). The same crosshatch pattern shows up as on the ABS knob, but it is solid.

The underside of the knobs is interesting. I had previously noticed that v1.1.6 either extrudes a bit more and/or does better at going back and filling small missed areas. For the v0.9.9 print, you can see numerous gaps that carry up into the knob. In the v1.1.6 knobs, the printer was diligent at going back and touching up numerous spots on each layer. I can't speak to whether the difference is in v1.1.6 itself or in the config file differences. Likely because of these touchups, v1.1.6 takes longer to generate a gcode file, and prints take longer. I'm not implying that v1.1.6 is better - I think I have work to do in tweaking retraction, acceleration, and who knows what else related to all these touch up spots. Right now I tend to end up with a slightly excessive amount of plastic in areas where the touchups occur. I wanted to experiment with a 1.x.x version since support capability was revamped in 1.0.0, and 1.1.6 was the latest available.

All knobs printed with calibrated esteps/mm based on feeding 100mm filament length, but not fine tuned for single wall print thickness or variation in filament diameter.