Monday, July 4, 2011

Classy Chassis

While the original Power Wheels Jeep covering was nice and all (sexy flame decals!), I got around to thinking that it was due for an upgrade.  The heavy mass of plastic weighed down the 'bot a good deal and really limited the placement options for various parts I've been hoping to add.  And so, two weeks ago some friends of mine came over to take a look at my pet project and we managed to pry off the plastic body of the Jeep.  It actually came off surprisingly easy.  It was only held on by four or so small washers underneath some plastic pieces.  Once those are pried off you only have to disconnect the steering shaft from the front wheel steering bar and the plastic just pops right off.  Here are some pics of the newly liberated frame.

Bare bones frame (Notice the four vertical poles, one at each wheel)

Torn off plastic from the Jeep

My old roomate(left) and MechE friend(right) standing over the remains of the Jeep

The workshop is no place for a woman!  Kidding of course, my girlfriend actually helped a fair bit with some soldering

The only problem with this frame the way it is is the fact that there's no support from the center, and no bracing, which basically means that while the frame should basically be a rectangle, any force from the side can shift it, causing it to take on the shape of a parallelogram.  And so I figured I'd buy some cheap aluminum, drill some easy holes, and get a fairly effective cross bracing system working.

1.5"x1/16"/6' Aluminum, about $10 from Lowes

Measuring and drilling the holes for the four vertical support poles on the frame proved to be far more difficult than I had anticipated.  Turns out that the poles had a lot of play, and this shifting made it very difficult to properly measure the distances between them.  It also turned out to be very difficult to widen the holes without any metal files so I had to use a drill instead.

Pictures of the two side braces in place.  These served mostly to add extra support to the cross braces and  the foam board layer that goes on top.

Here are some pictures of the cross braces once they had been put in.  However, after four hours of filing with a drill bit, I had pretty much had enough and gave up on doing side braces to make a rectangle.  They're also not really necessary since the frame came with some nice steel ones.

I also soldered some longer wires onto the motors to make them easier to access and plug into the batteries.

I cut out two layers of foam core board in the shape of the robot

The foam board mounted onto the robot.

Here's the junction between the top board and the frame.  Depending on how rough it handles while it's driving, I might install some springs at this junction to act as a sort of suspension system.  This will make the on board components, electronics, and especially my computer, less prone to wear and tear from vibrations and sudden jolts and movement.

So while this probably won't be the final frame design for the robot, it's at least a good prototype to work off of for now.  I'm currently in the process of figuring out a method of steering.

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