I have had a 3d printer for a while now, and I have a lot of the quality settings dialed in pretty well, but one thing that constantly bugs me is removing the raft from my finished prints. I am using Repetier and I have set the air gap to 0.2 mm. That led to much better results than the default 0, which were impossible to remove at all, but it is still not great. Are there any settings I should look at changing to get easier to remove rafts? Does the filament affect this? I am printing in Hatchbox PLA at high temps. I have a heated bed, and reducing the temp on that did seem to help. Maybe it keeps the layers on the raft from fusing with the layers on the part? Any help is greatly appreciated. Thanks.
I have been able to get rafts that peel off by editing the g-code after the raft has finished and adding an M104 set temperature command telling my printer to cool the nozzle down to about 40 degrees and then another M104 command to tell the nozzle to heat back up again. This gives the raft enough time to cool and then the raft doesn't weld to the rest of the print. If you are using a heated bed I would suggest trying the M190 command and turning that off after the raft and then back on after the first layer as well.
As comments suggest, a raft is not all that popular. Consider using a brim/skirt instead. I've had excellent luck with a 4-mm skirt, printing onto blue painter's tape. (Unless you consider it bad luck when I have a devil of a time getting some parts to release :-) ). Skirts are trivial to cut free from the object.
In a similar vein, if you run into trouble getting support structures to pop off the object cleanly, try to make them as thin-walled as possible.
I use raft almost always for ABS and PLA. My favorite setting for gap is somewhere between 0.11-0.13 mm both for 0.1 and 0.2 mm layer height.
By using 3-4 layers of raft I always get predictably good quality of a lower layer and not have any issues with removing prints from the surface which I had without using raft (especially with large or weak prints)