On Monday, September 25th, SAE BC will be presenting an Autonomous Driving seminar by Mercedes-Benz. The event will be hosted at BCIT, in building SW9, room 110 at 6:00 PM. The event is free for students, and includes food and beverages.
Please RSVP if you are attending, at http://register.saebritishcolumbia.org/
BCIT Racing and CSME will be hosting a welcome barbeque for first-year mechanical engineering students at 2:00 PM, September 5th, outside of SW9.
Come for the free food and swag, stay for the scintillating conversation on car repairs.
You can find CSME’s Facebook page here.
I’ve been spending this week migrating BCIT Racing’s homepage over to this self-hosted WordPress site. It’ll be cheaper, as well as more modern. Best of all, WordPress has excellent blog integration, so we will be able to post updates with ease.
I have also added a private forum for team members to chat. This will act as a semi-permanent library of information and discussion. We have felt that we’ve needed to bridge the gap between casual WhatsApp chat, and Google Drive information storage, so hopefully the forum will be a useful solution.
So long Wix…you served us well for a few years.
Spring break came and went much too quickly, midterm exams are back in full swing, and the competition in Rochester is rapidly approaching! Although we had a small supply issue over spring break which set us back a few days, we are nearing completion of our composite seat.
Constructed primarily of fiberglass, the new seat provides the driver with a much more comfortable seating position over the car seat that was in the vehicle last year. There was a bit of a learning curve to working with the fiberglass, but we quickly got the hang of it. Using various types of fiberglass mat, we laid up the head rest and base piece on acrylic molds. Despite using many layers of mold release wax, the polyester resin that we initially used bonded with our acrylic molds, so epoxy was used for the final pieces. This switch to epoxy also added to the strength and rigidity of our seat.
Unfortunately, due to cost, we could not make the seat entirely out of carbon fiber as we had originally planned. However, adequate strength was achieved using fiberglass, and the fiberglass was sandwiched between two single layers of carbon, for a little bit of race car style! It will almost be a shame to cover up that nice carbon fiber with padding come race time!
-Angelo and Jonathan
Alright spring break!! Time to relax, sort of..
A few of the major improvements that needed to be made to the electrical system was that the power supply was too heavy, and that maintenance was going to be difficult if it needed to be done. Also, due to changes in the rules for the 2016 competition a new brake light needed to be purchased.
After some quick calculations, it was determined a simple 9V battery should do the trick, which is a significant weight decrease from a golf cart battery. This year, the car will not be equipped with reverse, making the overall circuit simpler and easier to install. In order to simplify installation and maintenance, more connectors will be used and the new brake light features two holes on the sides for mounting. Last year’s brake light was mounted using a grommet, so if the light needed to be removed, it was easier to take off the entire mounting bracket which was mounted a little too close to the firewall, making it difficult to use any tools. A new mounting bracket is going to be made this year once the brake light comes in and measurements can be taken, and will be mounted in a way that will be more easily accessible. The new brake light also allows for removal while leaving the mounting bracket in place.
It seems this is like “the big push” for all the projects right now. Lots of people have been in the shop or doing work to the car over spring break. I know I have! It also seems like people are starting to get to the stage when they are fixing the really little things on their part. For the electrical system, it was the battery mounts, and the quick connector between the brake light and the power supply. After hours of troubleshooting, I finally found that I had made a bad solder in the way I made the quick connector. Once I had that figured out, it became an easy fix. When the battery mounts were bent to shape the battery holder, one of them was just a tiny bit too big and a new one had to be made. It’s an easy thing to make, but it sort of just slows you down. The electrical system is very close to being done now, just waiting on a few things. The hydraulic pressure switches to complete the system for the brake light, and the engine to be mounted to complete the system for the kill switches.
I forgot how heavy the old battery was. I weighed it and it turned out to be 25 lbs!! Completely unnecessary for what we were using it for. It feels good to know that we have reduced the weight by 25 lbs just by taking out the old battery.
We also gave the car its first wash ever! One of the guys was doing a lot of grinding and we just thought it would be so much easier for him and everyone else if we washed it. So someone was able to borrow a pressure washer and we brought the car outside last night to be washed. We had no idea how much dirt was there until it was all gone. Look at that shine!
The steering team was given the task of trying to correct several issues involving improving upon an existing steering system while keeping spending to a minimum. The main concerns with the existing steering system being
the structural integrity of the steering system,
repairing the damaged tie-rods,
and bump steer.
Another issue of less importance, but still to be investigated by the team is the position of the steering wheel to aid driver comfort and control.
In order to be able to modify and quantify the concerns for the steering system, proper measurements of existing parts and geometry had to be done first and modelled with CAD software to get a better idea of how to implement corrections.
Bump steer was seen as a big issue, so the toe angle of the front tires was measured through the full range of travel of the suspension, and it was found that the bump steer was excessive with a change of approximately 15 deg. This was seen as unacceptable, so CAD models were made with virtual measurements to compare to the real life ones ending with similar results; because of the agreement in virtual and real life bump steer measurements, different repairs could be tried on the CAD model and decisions could be made about the best option to correct the problem. After many iterations and stress calculations, the best solution was agreed upon: the tie-rod ends connected into the top end of steering knuckles would be flipped and tied into the bottom to better match the planes of the A-arms with that of the tie-rods. With this simple change, a maximum theoretical bump steer is seen to be around 3 deg — a huge improvement over the existing range!
To improve the structural integrity of the steering system, it was decided to insert support blocks as far out on the steering rack as possible. The best solution decided upon was using medium gauge sheet metal and making brackets with a bore large enough to fit a bushing and the rack. The support will be mounted to thicker gauge plates that will be welded to the frame of the baja vehicle via nuts and bolts. This should help considerably to limit the amount of bending stresses experienced on the rack as well as lower the forces acted upon the steering rack base.
Tie rod replacements have not been decided upon at this moment, but hexagonal extruded profiles seem to offer the best fit with very reasonable prices. Another issue still waiting to addressed is steering rack extension which should take place soon, and will employ tapped holes on the rack end and spherical ends and a threaded rod as the joining method.
In the coming weeks, part development and installation will ramp up with
the manufacturing of the support blocks, mounting plates and tie rod extensions,
welding of the mounting plates,
ordering of the new tie-rods
machining of steering knuckles to allow tapered studs on ball joints to be fastened on the bottom end, and
revised real life measurements of the baja vehicle steering system with all the improvements installed