Are you using 3M painter’s tape? Is your print head lifting the filament before it has a chance to stick? Does your build software actually have “settings” for print head speed. Makerbots generic software does.
I’m a newbie, but an older greek and have only used the MakerBot software to build, TinkerCAD etc to create and love them both. However, MakerBot’s software has a menu “setting” which I understand works well controlling the extruder and bed temps and I was advised by others (at 3DHub) to lower the “Travel speed” to 30 mm/s (they weren’t sure if this actually works on all machines, but in my mind, it does on the CTC Black series) and, as mentioned; the extruder temp to 205 degrees (I live in Michigan with a recent temp of 60-70, higher humidity etc.).
This my not apply to you, but works while still allowing me to breath filtered air:
I added a cardboard box over the top of the lid of the CTC 3D printer, then added another smaller box attached to a small filtered humidifier ($30.00) which does a great job of filtering the 3D printer odors, noise etc (poor man’s emissions control unit, not EPA tested, but then again; they let the automobile industry say my vehicle gets 17-24mpg and I’ve never done better than 15.4mpg on the highway.). Anyways, the air sucked through and around the 3D printer and seems to help the PLA harden quicker without adding another fan etc. Additionally, if the problem exist, turn the 3D printer object upside down and don’t use a raft.
Keep me in the loop and let me know what works and what doesn’t.