re-mix of Rover 2.0 planetary gearbox parts

thingiverse

10-5-2019 Update on Metal Shafts with Bushings. This version has proven more durable than previous iterations. To date, failures have occurred exclusively due to the sun gear on the motor shaft becoming loose and rendering that track non-functional. On occasion, the sun gear also broke (likely as a result of being loose from the motor shaft). These failures were typically associated with extended high-power operation. I did not encounter any during lower power ranges. If you have the option to print the sun gear in Nylon instead of PLA, it might be a viable solution for general use. An alternative is the 4:1 gear set I created as a remix of the original gear set. It has held up longer under high-power operation before requiring adjustments. You can find this here: https://www.thingiverse.com/thing:3883602 (NEW UPDATE 9/2019 - Metal Shafts on Gear Carrier with Bushings) I built a Rover 2.0 and incorporated the changes made by escexed in his "Planetary Gearbox Upgrade for FPV-Rover V2.0" to take advantage of the 4:1 planetary gearbox. After building and testing, I decided to modify the gearbox casing to accommodate the original Rover 2.0 motor mount position to maintain alignment between the bevel gears on the main cog and gearbox. This was simply a matter of merging the original Rover 2.0 motor mount with the gearbox output end. Not an elegant solution, but it worked. This allows the gearbox to be secured at the output end with 3mm nuts and recessed screws just like the original Rover 2.0 motor mount, as well as 3mm recessed screws in the locations used on escexed's original design. I also encountered a lot of flexing on the inner frame top louvers when tightening the long screws, which distorted the frame. This eventually led to a large number of fractures and eventually breaking off. These louvers are very thin and would likely have cracked in normal use at some point even without distortion. The gaps left by missing louvers allowed trash to find its way in during off-road use. I modified the inner frame components to make for a stronger top deck while maintaining internal clearances by adding 2mm thick "grates" in place of most of the louvers. Air flow may not be as robust, but it still allows air movement. I made another modification. The gear carrier has been a weak point on the build drive line. At high power, heat buildup on the shafts allowed for distortion and eventual failure. I did a remix of the carrier in which 4mm dowels are inserted in place of the printed shafts. The gear bores are modified to match the 4mm dowel shafts. I cut 4mm OD stainless tubing to 13.8mm lengths, which were pressed into the re-mixed carrier base. Some run-in is needed prior to mounting in the frame to ensure smooth gear engagement. While this change allows for a longer run time before failure, I found that extended use of high revs can result in enough heat buildup to allow the carrier plate holes to soften and deform. It lasts longer than with the printed shafts and allows higher speeds, but will eventually fail if used for a significant time at higher speeds. A new variation, similar to the 4mm dowel approach, is with the carrier modded for 2mm cap head screws (12mm long). A counter-sink area allows the cap end to be screwed flush to the carrier surface. The same 4mm OD 2mm ID stainless tubing is used to make bushings for the planetary gears. You use the same gears as with the 4mm dowel approach. The idea is that there would be no plastic/metal turning interface to build up heat, which can be transmitted to the carrier and potentially soften it enough for deformation. I have done some initial function tests but it has not been tested for long-term durability.