You need a crochet hook matching to the size of your thread: too thin - it divides and breakes the thread, too thick - you are not able to bring it through the loop. With the usual bobbin threads the strengths range from 0.4 (thin egyptian catoen) to 0.75 (Goldschild 18/3).In addition, there are other aids, such as the "Lazy Susan" or the stitch-catching needle, the use of which we will explain to you in each case.