I’m in the midst of printing all the parts for my first build and was curious what sort of print times people were getting when printing their parts? In Slic3r, I’ve called for 30 mm/s speed on perimeters, 50 mm/s on infill, 15 mm/s on small perimeters, and 15 mm/s on external perimeters. I’m finding that my parts are consistently taking ~1.5-1.6 x the time estimates given in the parts list, and Ryan says he printed at 30 mm/s. I can’t figure out how to get anywhere close to those times without driving all speeds significantly over 30 mm/s… I sped all those rates up 25% for the C-XY part, and it still took about 16 hours.
If you look at the extruder page you will see my settings. You should vary the speeds so much it makes for weird things between speed changes as the temp will spike and dip from the change in flow.
I use 30mm/s +or-10% that’s it.
The biggest factor in time though is layer height. With a .4mm nozzle I use .26mm
Interesting - I’ve never heard advice to control speeds to within that low level of variation. Most slicers come with larger variations by default - I’ve found I get generally excellent part quality with those defaults. Given that the infill I’m using is significantly higher speed, I’d expect faster print times, since I’m running the same layer thickness you use. The one thing that might explain some of it is the infill pattern - I’m using honeycomb rather than rectilinear. Gcode.ws estimates that only should increase print times by about 1.3% on the roller I’m currently printing, but I can guarantee its time estimates aren’t what I’m experiencing on my printer. Might be in acceleration limits I’ve got in the printer config…
The small infill percentage gain is easily offset by the 15mm/s outer and small perimeters.
As for the speed under and over percentage, just what works best for me. Seeing your 15mm/s outer than into a 55mm/s infill you have to see your nozzle temp drop when that happens, have you watched the temps shift? If you have a well balanced extruder maybe it doesn’t effect it as much. I have always used bottom of the barrel extruders so maybe that is why… but I do always get fantastic prints. I have always defaulted to quality over speed.
Yeah, I have watched hot end temps - its extraordinarily rare to see it ever move even 1 deg. C - when I switched to a MOSFET feeding the hot end, I noticed that the frequency of the LED flashing (corresponding to cycling of the heater) increases at these changes in speed, but still no change in displayed temp.
I’ve always gone with 15 mm/s on the exterior perimeter (its 30 on the interior perimeters) for quality over speed. I’m very satisfied with the quality I’m getting, but the speed is kinda painful 
Pretty sure I do all my layer heights in .3mm. That helps. I also use triangles for the infill, they do print faster.