Dear Gene,
Most pants, even work pants, have some tapering. When you just try to cut off and turn up a hem, there isn't enough material in the cut edge to neatly hem, especially if you do it by machine.
What you need to do is determine how much you need to cut off. I do it by folding the pants up to their finished length. I fold them to the outside and put a couple of pins right next to the folded edge. I then cut off the excess, leaving 1-1/2 to 2 inches for a regular hem, or one inch for a machine hem. Leaving the hem folded in place on the outside,turn the pants inside out and draw a line from the hip on the outside down to the folded edge. If you don't want much of a taper,
1/4 inch is enough to give you a good hem. Do the same thing from the inseam to the inside edge of the hem, using the exact same measurement you used for the outside taper. Cut away the excess seam allowance. You will see that now, when you turn down the hem, it flares out. This is what is needed to get a nice, clean hem. Re-sew the leg seams, making sure that you flare out at the start of the hem so that when you turn it up, there is room to sew.
For a machine hem, turn up 1/2 inch and sew around. Then turn up another 1/2 inch and sew again. Start at the inseam, so that the start and stop of the seam doesn't show.
For a regular hem, turn under 1/4 inch and sew. Turn up the remaining hem allowance and sew again.
Teri