Greenwatts

LM339 Worm Gear

The next step is to make the worm gear and attach it to the drive. Cut a piece of threaded rod 10cm in length and file down one end to fit tightly into the skill driver chuck and file the other end to fit tightly into the center of a bearing. I used a recycled roller-skate wheel bearing for this drive. Next cut one bottom (96mm x 96mm) and two side pieces (37mm x 96mm) out of ABS flat stock to make the gear box housing. In one of the side pieces layout and drill a center hole (17mm) and two mounting screw pilot holes to match the screw driver chuck and the two pilot holes drilled in the previous step. Assemble the gearbox housing with the side braces as shown in the picture below, with the worm gear firmly inserted into the screwdriver chuck mount, thread on a nut and press the bearing onto the worm gear then secure the screw driver on to the housing using two screws. The end of the worm gear with the bearing should just touch the side panel inside surface. Drill a hole in a piece of ABS flat stock equal to the outside diameter of the bearing, trim it square to fit the height of the side panel and then cut it in half and cement it to the inside of the side panel to hold the worm gear bearing in place making sure the entire worm gear assembly is aligned with the screwdriver. Place a small amount of epoxy around the end of the screwdriver chuck then thread the bolt to make contact and epoxy the bolt onto the worm gear as shown below.