Modified files for improved OpenRC Truggy printed parts performance

thingiverse

When I started printing the Open RC truggy, I discovered that sourcing parts in the UK was a major challenge. Specifically, driveshafts from Conrad were both expensive and hard to obtain, with lengthy shipping times and frequent stockouts. On the other hand, HSP 188015 driveshafts are remarkably affordable and widely available everywhere! This led me to create my OpenRC Truggy remix page, where I'll upload all modified files and explain my reasoning to make it easier for others to print this amazing machine. Here's a closer look at the parts involved: * 188015 axle shaft: This part was originally designed to work with Conrad drive shafts, which are expensive and difficult to source. Instead, I opted for HSP 188015 driveshafts, which are cheap and abundant everywhere! However, they're slightly too long for the original differential output shafts/axles. * To address this issue, I redesigned the output shafts with a stronger design that incorporates four 1mm dowel pins approximately 10mm in length around the main screw. This adds a metal, positive drive to the shaft output. While it's a bit fiddly, I recommend printing at 100% infill and using a 1mm drill to clean holes and a 2.5mm drill to clean the center hole to make assembly easier. You'll notice that the holes in the outer axle shaft are slightly further apart than the sun gear – this is intentional to ensure that the pins splay outwards when tightening, preventing them from splaying inwards and damaging the screw. Rear C-Hub: I took issue with bearings, realizing that if you have a 5mm shaft in a 5mm bearing, it's not ideal to make the hole the shaft runs through 5mm as well. This is because the inner race of the bearing isn't actually 5mm – it's more like 7mm. When the bearing is pressed in, the inner race rubs up against the back edge of the hole, causing binding. To fix this, I expanded the hole from 10.1mm to 10.2mm and made the internal hole 7mm, allowing the inner race to run clear and free. This made a significant difference! Steering Pin: Finding 5mm ball-headed pins was also a challenge – they're difficult to find and not commonly used. To address this, I modified the steering pin cups to accept HSP 02038 ball head screws instead. It's a tight fit, but it should work out in the end. Steering Block: Similar to the rear C hub, I expanded the bearing holes for easier bearing fitment. However, there wasn't enough space to expand the center hole without causing issues with binding. To fix this, I added a small shoulder approximately 0.4mm thick to raise the outer race away from the face of the hole. Servo Holder: I opted for the MG996 servo as they're common and affordable. However, the original servo holder was too small to hold it, so I modified the design to accommodate it. Be sure to use rubber grommets as well! Centre Differential Output Shafts: After strengthening the front and rear diffs, I found that the center diff was now prone to snapping either at the input side or output side joint. To address this issue, I applied the pin design to the shaft, increasing the strength of the power train even further!