Lineas de 1cm

Al realizar una linea de 1 cm no me aparece y no se porque, al moemot e exportar un documento no me paprecen esas lineas de 1cm que hago

Translated by Google:

Perhaps you need to zoom in. Maybe the camera is set too far away to be able to see an edge that short. Try using Zoom Extents to zoom the camera in to the model.