Some one on forum posted using a tap as the work and cut a worm gear. Then turned the worm to match the tap. As PMartin noted, the worm gear would ideally have a radius matched to the worm for more tooth contact.Your gear will need to be quite narrow to even work at all. Worm wheels (your gear) have teeth that have an angle that matches the angle of the thread helix. You won't have that with a regular spur gear.
Your gear will need to be quite narrow to even work at all. Worm wheels (your gear) have teeth that have an angle that matches the angle of the thread helix. You won't have that with a regular spur gear.