It's so nice to be done

The overall process of designing and manufacturing our slotbot took a few twists and turns and hit a few bumps along the way. Our original designs for both the cart and the chute were modified as time went on. We also made a few mistakes during manufacturing process which chipped away at what little time we had to build our bot. However, our finished product turned out to be a very competitive design.

The initial process for design and creativity was done individually and also lead to the first obstacle in developing a final product. Each of us invested a large amount of thought and time developing our own ideas only to have them stripped down by the team. Comprimises were eventually made but it did slow the development of the final design. This could be remedied in the future by starting the group portion of the process before each person narrows their work to a single design.

The manufacturing of our MCM was probably the part of the assignment in which I learned the most. I was very unsure of how to properly and safely use the equipment in the shop prior to this portion of the project.  Bob Coury soon became one of the most valuable instructors of the class. I started working in the shop as soon as we were allowed and asked as many questions as I could. It wasn’t long before I became proficient using the lathe, band saw, drill press, laser cutter, and the drilling portion of the mill. However I never did get to use anything involving end milling or auto driven lathe/mill. Hopefully I will get the time to learn these in ME350.

Although the manufacturing process was successful for learning it was also a hindrance for multiple reasons. The first of these reasons is due to either a lack of prior experience or because of a careless mistake made by us. We had a tendency to either not be able to make a desired part or to make a mistake while making a part. A particular case when we couldn’t make a desired part we could not make a cut that we wanted using the available equipment so we turned the single part into two parts. This took more time and also required us to change our CAD drawings. As for the mistakes, there were a lot of them. We at times either did not come the realization about the how parts fit together or carelessly cut or drilled an area that did not need to be. A lot of extra parts were made in order to get the correct part completed.

The other reason the manufacturing process slowed our project was due to availability of equipment. There were 32 teams and 4 lathes and 4 mills (if they all worked). This led to a lot of wait and hope time. Hopefully, this can be resolved for future classes. Perhaps shorter time blocks per team and maybe an earlier availability for the manufacturing portion of the class.

The competition…. As fun as the idea sounded to me in the beginning, I ended up very disappointed when all was said and done. It seemed that the performance of our cart was incredibly dependent upon the power supply we were given. During preliminary testing our cart moved both forwards and backwards quit well, and only had some difficulties in turning right. In order to compensate for our lack of turning we decreased friction on our front wheels. This seemed to work well in the first round of the competition, but not so well in the second round.  The first round our cart maneuvered in all directions fairly well, but in the second we could barely even move in the forward direction. Because nothing mechanically changed between rounds it led me to believe the power supply was not as strong. Upon coming to this conclusion I spoke with a few other teams each of which seemed to have had similar problems. Though the competition did not affect our grade it was part of why we all worked so hard on our projects and was slightly irritating to think it could have come down to luck of which battery pack you received. In short yeah to mechanics and booh to electronics.

Reflection by Cameron McKenna

Looking back at the course as a whole I wish I could do it over again, with the change of doing things slightly differently. I learned a lot with regards to design and manufacturing, some during lecture, but most of what I learned came from working in the shop on our slotbot. Before this class, I had never used a mill or a lathe. Learning how to use these machines will be an integral factor in my success here as a Mechanical Engineer as I certainly will be using them in subsequent design classes. I also learned a lot about the manufacturing process, mostly in terms of the order that these processes be done.

Learning how to use SolidWorks was fun. I thoroughly enjoy working on CAD and was able to pick up SolidWorks pretty quickly as I have prior experience with AutoCad Inventor. These programs are very similar and I found it very interesting to learn another as there is not one program that is used in the industry.

Being that this is the first semester of slotbots II it is understandable that there were aspects that needed improvement. The biggest, as many other students have probably stated is the amount of time spent in the beginning of the semester on the creative process. I agree that creativity is important, but learning more about the design process and the resources available to us would have moved the final stage of manufacturing along more quickly. I also think that creating teams earlier and opening the machine shop earlier would be beneficial. And if it is a concern that teams will not take advantage of this time, a stricter requirement of attended shop hours for each team should be enforced.

The most beneficial part of the lectures for me was the material relating to our actual project i.e. couplings, gears, bearings/bushings. I would have liked to see more material presented that we could use on our project. Things like how to use the machines, safety tips, good practice for machining, like which edges to measure from and use the edge finder on, center drilling, and mounting pieces in vices. I am sure many teams had to make major changes in their machines because they were not able to do something that they needed to or simply because when they tried to it did not work and ruined their material

A good way to avoid this is to have more in-shop assignments like we had mid-way through the semester during the beginning weeks when the work load is very small. After everyone is trained having these assignments would help open people up to all of the available processes. From personal experience I know that Josh and I did not once use an end milling bit, simply because we really didn't know how. We just stuck to using the band saw and then filing our pieces smooth.

Overall I think the course material was good aside from learning too much about industry processes like "cold-rolling" and steel types and not enough information relevant to our project.

I was also disappointed in the power supplies used because they were not reliable because some rounds our car would drive just fine and others it would barely move. stronger motor could also be used because as this competition is much more complicated than slotbots I more elaborate bots were created that required more power.

My performance in the class could have been improved by knowing more about how our gearboxes performed under loading. It seemed that when we included our timing belt/pulley assembly it made our wheels harder to turn and consequently harder for our motor to deliver our desired output. I could have also performed better had I known more of the machining principles before entering the shop seeing as our group spent the whole first week making and remaking wheel shafts because we were making holes the wrong size, tapping them wrong, or bending them in the arbor press.

This course has taught me many things and I enjoyed the project. I did not have much contact with Sei Jin but Davor and Mark were both really good GSIs.

I look forward to ME 350 and as I believe it was Toby who said it, I will probably regret suggesting more manufacturing time for the 250 students. But if it makes for a higher scoring and more exciting competition than that sounds good to me.

Final Team Documentation

Our Slotbots strategy required two modules. Our Most Critical Module (MCM) was a cart that was driven around the table top. A pen and gate assembly allowed us to collect and secure balls on the table. Our second module was a chute that, when deployed, served as both a way to toggle the lever and score the balls carried by the cart. A small secondary ramp was placed in the slot and used as a dumping zone. The balls rolled down it, into the hollow chute, and finally down the scoring ramp.

This approach was chosen because it offered multiple scoring options. For example, if our opponents were able to toggle the slot before us, we could use the cart to carry balls to the opposite cone instead. We also wanted a creative way to attack the problem, which we believed this would accomplish.

The two modules are pictured below, and explained in more detail:

The Cart

As mentioned above, the cart was designed as our primary offensive option. Though our focus was to use it to deliver balls to the slot, it was equally capable of taking balls to our cone if the chute was beaten to the lever. Therefore, it was critical to any success we hoped to have in seeding and the competition.

The pen and gate assembly on the front utilized gears and linkages. The gate could be raised and lowered, allowing us to capture balls. The shape of the pen helped ensure that the balls could not escape as we were trying to collect more. The gate was bent at the bottom so that it pushed underneath the squash balls, and prevented them from getting stuck. The open bottom provided an extremely simple deposit method into either the horizontal slot chute or the cone.

The laser cutter, waterjet, mill, band saw, drill press, and metal bender were used in the manufacturing of this module.

The Chute

The chute was designed to act as a fast way to toggle the lever and open our side of the slot, and to accept and score balls from the table. A solid, stationary base was placed in position with velcro, ensuring it wouldn't move during game play. Two rails, purchased from McMaster, were attached to the inside of the vertical walls. Two sliders were attached to the aluminum chute. Slots on the walls allowed us to adjust the angle of the chute, and test for the optimal setup prior to the competition.

At the start of the match, the chute was kept in position by a short aluminum pin. When play began, a motor was used to pull the pin. Utilizing only gravity, the sliders then moved down the rails, allowing the chute to fall toward the lever. A two pound block was also secured inside the chute at the top to allow it to hit with more force.

A horizontal slide was placed into the slot. When the cart drove over the slot, balls rolled down it, into the hollow vertical chute, and finally into the scoring ramp.

A combination of the laser cutter, waterjet, mill, band saw, drill press, and metal bender were used in the manufacturing of this module.

Other Notes:

• The power supply was mounted directly to the cart to reduce wiring.
• A quick-disconnect was used to allow the car to detach from the chute once the pin was pulled. This allowed it to travel freely and eliminated the possibility of getting tangled up in extra wire.
• A complete parts list, including costs, can be found in the post below. We remained slightly below our $100 allotted outside budget.
• We were able to rank 4th in the seeding round, and advanced once in competition.
  

Parts List!

Our final parts list can be found at http://goo.gl/th3JY.

Final Video: Shorter Version!

Our final video was apparently a bit too long to be shown as filler material before our rounds. To remedy this, we present - "Final Video: Blitzkrieg Director's Cut!"

Wrap Up Video

Below is Chaos Theory's final video documenting the semester's events. We're generally pleased with the work we've done and the quality of our modules, and are looking forward to the competition on Thursday!

 

[Edit 12/08/10, 12:22. Higher Quality Video]

Modules Completed!

We completed both of the modules today for the MS9 presentation. All parts have been manufactured, and all moving parts ran as expected. However, we still have some troubleshooting to complete before we're ready to compete.

The chute needs to be weighted more so that it can overcome the friction of the sides of the chute. We plan to add weight however we can, and based on an initial massing of both modules we can add up to 5 pounds. We also plan to add an additional pair of "sliders" on the chute. These will better support the chute on the rails, and should make it descend more smoothly.

Additionally, we will be replacing the pulleys on the car's front wheels. The current pulleys broke during assembly, which severely compromised performance during testing. Once these new pulleys are installed, we should be able to turn much more easily.