Week Eight - Finally?

Hey guys!  The car finally started moving this week, but there's still a LONG way to go for competition.  Given that the first competition is at the end of April, I'm really thinking it won't be ready in time.  That being said, here's what did get done this week:


TUESDAY


So I'm trying out a new format; bear with me.

The lead engineer was sick on Tuesday, and not many guys showed up, which both led to a relatively slow work day.  The lead (Coleman) messaged me in the group chat we use and tasked me with making new bushings for the brake pedals.  They're small plastic cylinders that sit between the brake pedal brackets and the pedal itself, to avoid the pedal slipping around.  I started out by taking measurements, and I made a rudimentary sketch in my notebook so I'd know how much to cut the plastic.  I won't ruin this blog with my awful art skills, but the sketch did serve its purpose.

I took my sketch and long plastic dowel to the band saw lab to cut the rod down to a size that would fit in a lathe.  When I got there, I noticed that the saw had been taken apart, and the blade removed.  I'm guessing it was to replace the blade, since I'd heard several different people complaining about missing teeth and dullness, but whatever the cause, it meant I couldn't cut with it. Luckily, I found a hacksaw back in the shop, and (twice) luckily, I was cutting plastic, not metal.  If I'd needed to cut an aluminum or steel rod, I would've just had to wait until the saw was fixed (side note: it finally was on Saturday).

After I had an appropriate-length piece, it was just a matter of lathing it down to the other proper dimensions.  The process was a bit tedious, but using machines hasn't yet gotten old (I doubt it will for me).  As interesting as using the lathe was, I don't think I  can manage to describe it in a way that isn't 100% boring, so I'm going to skip ahead to the finished product.

My original bushings were almost twice as big as they needed to be.  The reason was that placing calipers in between the brackets was near impossible, so I didn't measure and accurate length.  There was also a plastic piece attached to the pedal on each side, which I thought at first could be removed, but when I realized it was there to stay, I had to cut the bushings down much further to fit.

Once I realized they needed to be smaller, I was still in the frustrating situation of being unable to measure the necessary size correctly, so the next half hour or so saw me going back and forth from the machine lab to the shop to test-fit them on the car, and then cut some more.  At last, they fit beautifully.

The original (too long) bushings looked like this:

They fit into the brackets like this:

{I couldn't get a picture of them on the pedal, because when the pedal was between them, they were impossible to see.}


THURSDAY


Thursday was the least-eventful day.  It usually is, since I'm only there for 4 hours, and the weekly meetings take up at least one.

To start the day, I helped attach a box to the back of the brake light to hold it in place on the splash guard.  That meant first removing the old rivets from the box (just a small, X-shaped piece of sheet aluminum).  Next, I held it in place over the light and drilled through the pre-existing holes in the box into the back of the splash guard.  Then, I finished the installation with fresh rivets to secure the box (and thus the light).

The rest of the day was mostly watching stuff get done, until about 5:30, when the project leads left the shop for the lead meeting (which always happens before the full group meeting at 6).  Coleman told the 4 of us interns and 2 other members left in the shop to clean up until 6.  After putting a few things away each, everyone else stopped working and just sat around.  One of the other interns was working on his deliverable, so I'm not counting him, and one of the others helped me a bit, but I did 90% of the cleaning.  I'm the only one who even picked up a broom.  At 6, they all left for the meeting, and I kept cleaning for at least 10 more minutes, until the entire lab was tidied up.  After that, I went to the meeting with everyone else.  I admit I was pretty frustrated at the general laziness of the other guys, but I also didn't make a big deal out of it to them, so I'm partially responsible for the fact that no one helped me.  But I digress...

SATURDAY

Saturday is when the car finally drove!  I guess they had driven it a little on Monday, but Saturday was the first day I saw it.  Before it was ready, though, we had to replace the oil in the engine and the gear box.  That was a pretty self-explanatory process, but it was somewhat time consuming, because the entire CVT had to be removed to access the plug in the gear box, and the engine kept dripping for several minutes.  Eventually, the necessary amount of new oil was measured out and inserted into the engine/gear box.  Once the CVT was put back on, one of the guys on the team gave me another big open-ended solo project (my favorite!!) which I will try to best explain with images.

THE PROBLEM:

The seat belts attach to the chassis through two large rectangular holes in the firewall, which leaves two large rectangular spaces for heat/fire to reach the driver.  I had to design and manufacture a box to enclose the seat belts, shielding both them and the driver from any harm.  Here's a picture of the exposed seat belts on the car:

I started out by taking measurements of the opening, and sketching basically a standard prism with those measurements.  I had to modify the front face, since it needed to be open and have circular holes carved out to fit around the seat belt and the pipe of the chassis.  It also needed to rivet onto the firewall, so I had to design tabs on it as well.

My design boiled down to two pieces, riveted together into a box.  The first piece was a rectangle with half-inch squares cut out at the corners, and the edges folded up to form a half-inch lip around the perimeter.  I made this piece correctly on the first try.

The second part formed all four of the walls, and the open front face.  It took me three attempts to get it right:

1) When making my designs, I overlooked the fact that the box was not square, so my wall piece had all the wrong sides for the back piece.

2) I corrected my designs and cut a new piece with the right dimensions.  I cut and bent the metal into the square I needed, but I forgot to cut the circular pieces first.  Since I had already bent it, using any machine or tool to cut the holes would've been much more trouble than it was worth.  If that had been the only issue, however, I could have found a way to do it.  That being said, there were a couple other problems that warranted making a new part just for simplicity's sake.  The first was that I had neglected to make an overlap on the wall part, which would've left a large gap on one edge of the box.  It's possible it wouldn't have been noticeable once the box was completely assembled and riveted onto the car, but I didn't want to take the risk.  The second issue was that I had bent all the tabs inward, which I realized would put them inside the hole I was working to cover.  Again, it's possible I could have bent them back, 180 degrees, but that might have weakened the metal, another risk I didn't want to take. Long story short, I scrapped the second attempt and hoped that the third time would be "the charm."

3) I adjusted the dimensions to accommodate a half-inch overlap on the wall piece for a rivet to hold it together.  I also made sure to cut the circular holes first, and test-fit them before bending the metal.  I ended up needing to make them larger later anyway, but it was easier than it would've been to start them.  I also bent the tabs outward, so they would attach to the car correctly.

Finally, when I had two pieces that fit together and fit onto the car, I riveted the whole box together, and I'm proud of the end result:

During the several hours it took to make that, one of the other members helped me learn how to use the mechanical punch and the sheet metal bender.  He also decided to work on an alternative design based on last year's boxes, since we did need two anyway.  The old box was a much  more complex shape, more trapezoidal than rectangular, because the previous car (Gold) had different drip pans, so the box had to fit around them.  My guess is that the team will end up using his design, since it probably looks better (although no one will see them anyway), and it was crafted a bit more expertly, but I'm no less proud of mine.  After all, he (albeit incredibly well) copied a pre-existing box.  I took measurements of the car to design and create my own from scratch, so at the end of the day, which one is better?  His, definitely his, but he's in his second or third year of college engineering classes :)

The box build took me until about 3:00 (I got there at 10)  A little while later, the car was ready for testing!!  I'm going to explain a little of what exactly we were testing, but most of the rest of this blog is going to be pictures and videos of the car driving around.  Why?  Because it's actually running!!

First time starting the car that day:

Driving around:

 Checking the brake pressure:

 More driving around:

Testing out the car's maneuverability over relatively small gravel/dirt:

So, the main thing we were testing was the brakes.  Coleman was driving, and his goal was to get it up to top speed (around 30-35 mph) and slam on the brakes to put maximum force on the system.  As you can see in this video, it doesn't stop immediately, because the wheels don't lock up completely.  That was a big problem.

 After a few minutes of mixed success (depending on the terrain: dirt, grass, gravel, pavement, etc), we took the car back inside and adjusted the brake pads.  That meant taking off the entire wheel to get to them:

The best close-up I could get was this one.  The brake pads are the black plastic pieces in the middle.  When the driver pushes the brake pedal, the pressure pushes the brake pads together, and they (are supposed to) grab the wheel rotor to stop it from turning.  That wasn't happening during the drive.

 We also put on new rotors to see if the pads would grab them better.  The rotor is the dark metal circle on the inside of the wheel, with the funky pattern of holes and slots:

After maybe 45 minutes or so, we took the car back out, with new rotors and cleaned brake pads, to see if they would make a difference.

I decided to get a little artistic with the angles :)

The car seemed to be braking less evenly this go-round.  I mean that the left wheel was now locking up almost perfectly, but the right one wasn't at all.  Basically, one side got better, and the other got worse.  It successfully braked with both wheels on grass, but on the dirt, gravel, and pavement, it proved unsuccessful.  I took a couple more videos of the car driving, but I unfortunately put my iPad away before it braked on grass.  I had already written it off as a universal problem, so I missed the opportunity to put it in the blog.

Well, that does it for this week!  Due to my crazy April schedule, I've put myself a whole week ahead on hours, so I'm heading into my final week.  I won't have much chance to go in after that, so here's hoping for an eventful and productive last few hours, and I'll check in with you guys when I hit the big 150!

Cheers!