It really depends on the liquid you are using, and if it is a new/used cartridge. You should elongate a paperclip and put it down the side of the filler and cart to make an airhole and then drop by drop as it soaks in get somewhere between 9-13 drops in. Drops are different from different bottles. A 3ml bottle drop is completely different from a 5/10/30 ml bottle. Get the airhole thing going and move the filler around as you fill.
With the PTB Made Easy mod, I get 10 drops on every refill: http://www.e-cigarette-forum.com/forum/cartridge-mods/52430-ptb-straw-mod-ptb-made-easy.html
Just about every question you can have on the 510 is answered on the Everything You Ever Wanted to Know About Your 510 guide. (Click the link.)

Maybe I can help. What problems are you experiencing?I so want this to work and can't get there!!!!!! I have tried numerous times and have the ptb's all cut and ready to go. *CRY*![]()
This is absolutely the correct answer.It really depends on the liquid you are using, and if it is a new/used cartridge. You should elongate a paperclip and put it down the side of the filler and cart to make an airhole and then drop by drop as it soaks in get somewhere between 9-13 drops in. Drops are different from different bottles. A 3ml bottle drop is completely different from a 5/10/30 ml bottle. Get the airhole thing going and move the filler around as you fill.
after about 4-5 mine pools at the top