Nylon (Taulman 645 and 618) has a very specific printing temperature of 245C with little or no bed temperature, but requires many layers of adhesive on the bed as nylon needs a printing surface with texture in order to avoid warping. Using several layers of hairspray and adding a brim or raft to your print can help the first layer of the print from warping and peeling off the bed. Printing at a lower speed can also help in proper layer adhesion.
Note that when printing with nylon, the printer must be in a well ventilated area. The "smoke" that comes out of the heated end of the extruder when the nylon is fed through is water evaporating and does not mean that it is burning.
A few notes on printing with nylon 645:
We find that printing with a 0mm retraction helps reduce bubbling in your print as water is evaporating from the surface of the filament. If possible, try to print one print at a time to reduce bubbling further.
Always use a raft when printing with nylon - even with a bed adhesive. The raft will come off easy and you will have a perfectly even surface - no curling.
Printing with a larger nozzle will give higher consistency. We normally print with a 0.5 or 0.8 mm nozzle and have seen higher consistency.