You can certainly sew over pins - however if you have a computerized machine and you hit one of those pins you have a good chance of throwing the timing out on your machine. When this happens you have no choice but to visit Mr. Sewing Machine Repair Man. Guess How I Know This! Yep I have done it. I am lucky and know someone who repairs machines and he was able to get me going the next day - otherwise it would have been a 2 week wait at the shop. Of course I was working on a deadline. Now I avoid them, that isn't to say that every once in a while I miss pulling out a pin, but when I realize it I have to say a little prayer of thanks that my needle didn't hit it. You can even hit a pin sometimes and not throw your machine out but that is just luck.