your chain could be sheeeot... it would not be the first time one got through that is not heat treated properly or is soft steel plated chisels so they do not retain a edge. im another fan of the pferd 2 in one file, it uses any brand of replacement rat tail file and is very simple to use giving excellent results even in the field but a stump vise makes it even better... i like to clamp 7-8 inches out from the power head to give a large area held steady to file but if your bar rails or groove is worn your results will suffer. using those 2 tools i have successfully used my first chain up until the chisels were gone, hand filing I would get 3-4 sharpening's per chain before taking it off and throwing it in anger. 30 bucks for the file, 20 for the vise but getting 20+ tanks out of a single chain vs 3 is a huge money saver, replacing the files costs about 2-4 bucks. that file saved me 300+ bucks on chains this past fall/winter/spring just by hitting the chain with 2 strokes per tooth at every gas refill and before starting the saw for the day.