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# 450 RPM on 2.75"
The best drivetrain
In this tutorial, we'll show you how to build a 6-motor 450 RPM on 2.75" drivetrain, one of the best in the world. This drivetrain is fast, low-centered, and easy to build on.
We'll start with the wheel assembly. We used 1.5” screws, ¼” spacers, and nylock nuts to connect the 48T gears to the 2.75” wheels as shown. There are two screws that go through opposite sides to balance the weight.
Next, we attached the bearing flat on the inner drive C-channel using one zip tie. That’s because the screw joint will also help to secure the bearing flat in.
After that, we found the best spacing for the screw joint. We used washers on both inside edges to reduce friction, and keps nuts to hold the screw joint in place.
Here’s how it looks when it’s all put together:
Before we could add the bearing flats, we had to shave down the corner of a few so they wouldn’t hit the motor caps. We used a sandpaper attachment on a Dremel and cut the corners like so:
Then, we attached all of the bearing flats on the inside of the drive using zip ties. The shaved upper corners of the bearing flats are circled in green.
Next, we attached the three motor caps using 0.25” locking screws:
Then, we added the rest of the wheels using the same screw joint:
Next, we mounted the bearing flats for the motor axles, using zip ties to save weight.
After that, we found the best spacing for the motor axles. Again, we used washers to reduce friction. The shaft is 3” long, and fits perfectly into the motor without sticking out past the bearing flat.
And with that, the left side of the drivetrain is complete!
We made the right side in the exact same way, except mirrored. To attach the back cross-brace, we boxed the back hole of the C-channel and attached it to a 1” standoff going up. The boxing adds extra stability and prevents the C-channel from bending.
We attached the rest of the cross-brace in the same manner, like so:
Finally, we added the front cross-brace using 0.25” locking screws and eight ½” standoffs. Two cross-braces greatly increases the stability of the drivetrain, and prevents it from bending over time.
With that, the drivetrain is complete!
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