Mikey's Lab

An all out assault on ignorance

Planetary Rover – Chassis Build Part 1

Dec
27

Credit where credit is due, my chassis, at least the drive section, was heavily inspired by this video:  https://www.youtube.com/watch?v=3Zx7t…

He did some really good work, but we are going to make some modifications and push the design a little further!

So lets look at what we need to get started building the rovers drive chassis!

Tools Required
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  • Drill
  • Drill Bits
  • Hacksaw with a plastic cutting blade
  • Miter Box
  • Dremel with a cut off wheel
  • Tape Measure

Parts Required
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  • 1″ PVC Pipe, I purchased 10′ but have a lot left over for modification and expansion
  • 6 * 90 degree PVC Corners
  • 4 * 45 degree PVC Corners
  • 3 * PVC ‘T’ Joints (or two and two end caps)
  • PVC Glue (did not end up using this yet!)
  • 4 aluminum plates with 4 pre drilled holes
  • 10 – 24 3″ bolts
  • 10 – 24 2″ bolts
  • 40 * 10-24
  • 1/4-20 Threaded rod
  • 20 * 1/4-20 nuts
  • washers
  • Blue Lock Tight
  • Sand Paper
  • Motors – http://amzn.to/2hY8GGq – not really used in this part

Lets Get Started
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First off lets start with a cut list, fair notice, in the next video I make some modifications to the chassis that involve changing two of these measurements. I have left the originals here, but will detail the changes in the post for the part 2 video.

So we will need to take our PVC pipe and cut the following lengths:

  • 2 * 18 cm
  • 2 * 20 cm
  • 4* 13 cm
  • 4 * 10 cm
  • 2 * 5 cm

After these cuts are done you will need to clean up all the cut edges, in the video I sued sand paper for this but you could just as easily use as file to get the edges nice and smooth. The reason for cleaning the edges, even though they will be hidden is that we will be running wires through these pipes. Because of this we do not want any sharp edges on the pipe that can damage the wires.

Now we need to make some spacers, since I could not find end caps. If you can just buy the end caps, this would be a much better solution.

To make these I just cut two sides off of one of the ‘T’ pieces I had purchased.

Assemble the static part of the leg
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We build the non moving, or static, part of the legs in the following order

  1. Insert a 5 cm spacer piece into one side of a 45 degree bend
  2. Place and end cap (or spacer we made) on the other end of the 5 cm spacer
  3. Insert a 10 cm piece into the other side of the 45 degree bend
  4. Place another 45 degree bend on the other end of the 10 cm piece
  5. Finally insert a 18 cm piece into the other side of the 45 degree bend

Obviously do this twice as we will need to legs for the rover.

Assemble the bogie part of the leg
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We build the front pivoting section of the frame with the following steps

  1. Insert a 13 cm piece into a 90 degree bend
  2. Insert another 13 cm piece into the other side of the 90 degree bend

That is all there is to the front side one the PVC frame!

Assemble the two parts of the leg
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Attaching the two pieces of the leg via the metal brackets, so one end is static and the other can pivot is a fairly straight forward process. Take one of the metal brackets, place it on the short end of the static part of the leg so that two of the holes or on the leg (one on the end cap or coupler, the second on the 45 degree bend). We will use this a drilling template to drill two hole big enough for a 10-24 bolt to fit through.

Once these holes are drilled, we will take the moving part of the leg and drill a single hole in the center of the 90 degree bend.

It is VERY important to ensure you are dead straight going through both sides of the pipe, a drill press would greatly help with that!

Once all the holes are drilled, go ahead an take a 2 inch bolt, put a washer on it, pass it through the metal plate. Then pass it through on of the holes on the static piece of the leg, out the other side, place another metal plate on the other side, add a washer, and start the nut.

Before tightening down the nut, take a small amount of thread locker and apply it to the threads of the bolt, and tighten the end not down over the thread locker.

Repeat this process of the other two holes.

Once the thread locker has a chance to dry go ahead an trim the bolt to size with a dremel and a cut off wheel.

Now we just need to do the same thing with the other leg!

Build the first body level
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With the remaining 4 90 degree bends, assemble 2 * 10 cm pieces and 2 * 20 cm pieces into a rectangle.

Mark the center of each 10 cm piece, on one drill a hole through the center, on the other drill two holes 2 cm on either side of center.

Assemble the frame
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Now we need to take both legs, and set one as the right and one as the left. Find the middle of the horizontal section of both legs. On one of the legs drill a hole in the middle of this section. On the other leg drill two holes 2 cm on either side of the middle.

Now the frame can be bolted together with 3″ bolts.

Conclusion
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This is pretty much the end of the build for the PVC chassis. In the next video we will take a look at a couple modifications I decided to make, as well as how we are going to mount and wire the motors. Following that video we are going to get to the exciting stuff, the electronics! So stay tuned, we are going to science the s@#$ out of this!

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