Fastmike Heng Long Worm Gear Drive

thingiverse

These units have been discontinued and parts are no longer available for purchase. An alternative gear drive system is now available for use with Heng Long Battle Tanks. This system can only be used in conjunction with the "Fastmike HL Worm Gear Drive Set" which can be found on eBay. The gear sets are manufactured from solid stainless steel stock and have very close tolerances for the bearings. Each gear set comes equipped with aluminum spur gears that match the drive gears on the Heng Long RS380 motors. Five rubber sealed RC car bearings are used in each drive instead of bushings for smooth power transfer. These drives weigh half as much as the standard steel gear drive, allowing for more power and easier turning. The kit allows users to change the final gear ratio by swapping out spur gears. A 28T tooth spur gear is included which matches the stock final drive ratio. Additional spur gears with 26T, 27T, 29T, and 30T teeth are also available. The 26T-27T gears will increase top speed but reduce turning power, while the 29T, 30T gears will decrease speed but provide more power. Users can choose to use their stock motors and controllers or opt for motor plates and shorter motor supports that accommodate RS540 motors and controllers. For RS540 motors, a 48P, 38T tooth spur gear and a 48P, 16T-20T pinion gear are recommended. The Gear Drives are universal and can be used with either short or long axle HL gear drives by switching sides on the mounting plates. They are designed to fit most tank models without requiring removal of any stock components. Some models may require trimming of post/s to accommodate the drives. There are two different drive styles available: long axle drives which require a bearing button through the tank hull, and short axle setups that use a bearing arm to hold a bearing next to the hull. The long axle setup is required for chassis numbers 3838, 3839, 3889, and 3918. For users who wish to print their own gear cases, the design is straightforward with minimal support required. However, some areas may require raft or exterior support during printing. Total print time is approximately 6.6 hours for all components. To assemble the gear drives, a few specialized tools are needed. A #4 drill bit is recommended for drilling most screw holes, while a .093" drill bit is necessary for motor mount plate screw holes to prevent spreading of the cases apart. Locator pin holes on the mounting plates should be drilled to .101". The full install requires the following fasteners and bearings: (4) 5mx12mx4m MR125-2RS sealed ball bearings, (6) 8mx14mx4m MR148-2RS sealed ball bearings, (4) M2.5-0.45 x 5m Socket cap screws, (14) #4 x 3/8" Pan Head Sheet Metal Screws, (10) #4 x 1/2" SMS, (8) #4 x 3/4" SMS, (2) 4-40 x 5/8" machine screws and nuts, (4) #4 flat washers, and (2) 6" wire ties. If using RS540 motors, an additional set of fasteners is required. Two pages of JPG installation instructions are included in the files for reference. The worm gear sets will be listed on eBay when available, with options to purchase either a set with just the gears or one that includes all necessary bearings and fasteners for a standard install. This project was started three years ago with a YouTube video, and it is hoped that users will enjoy using these gear boxes. Update: A new mount plate and bearing button have been added for the Leopard 2A6 tank base #3889 to be used with the long axle setup.