Armature end insulator for a power tool motor

An electric motor comprising a stator and an armature received within the stator for rotational movement within the stator, the armature comprising:

• an armature shaft on which a commutator is mounted;
• a lamination stack also mounted on the armature shaft and having a plurality of radially extending teeth, said teeth forming a plurality of slots therebetween arranged circumferentially around a periphery of the lamination stack;
• an end insulator arranged at an end of the lamination stack, the end insulator having a base portion fitted around the armature shaft and plurality of insulating teeth corresponding to the radially extending teeth of the lamination stack, said insulating teeth forming a plurality of end insulator slots therebetween, wherein at least a portion of the insulating teeth has a greater thickness than at least a portion of the base portion, each insulating tooth comprising a first extension surface extending from an outer surface of the base portion at a first angle of 30 to 60 degrees with respect to a plane of the outer surface of the base portion, and a second extension surface extending from the first extension surface at a second angle with respect to the plane of the outer surface of the base portion that is smaller than the first angle;
• and
• a plurality of coils wound in said lamination stack slots and said end insulator slots.