Day 10 – Send CADs (1/13/2020)

Authors: Andrew Georgioff, Ritik Mishra, Sarthak Agrawal


We received our power cells in the mail today and learned that they were even grippier than we expected. We also had our Noodles & Company fundraiser today and had a successful turnout.

Also, we got our power port field element today! 

Drive Train

We assembled pneumatic wheels for our drive train today, which had come in the mail. We chose pneumatic wheels to easily navigate the 1.5-inch bump in the rendezvous point. We also received custom cut spacers for our drive train shafts today, and we also sent our frame CAD to CEM.

One catastrophe was prevented today. The raptor frame holes on the drivetrain were CADded to be .201” (#7), but they should have been .159” (#21). This would have been catastrophic because size #21 works for our 5/32” rivets but the size #7 does not. Fortunately, it was caught in time for the fix to be made.

We have also CADded the bumpers. We are doing three new things this year. First, we are bothering to CAD the bumpers. In past years, we just winged it, resulting in messy bumper brackets and mounting locations. Hopefully, by planning the design of the bumpers ahead of time, it should be much easier to make them. Second, we are counterboring our bumpers a little bit. This is because we are putting the bearing flanges on the outside of the frame perimeter. This way, when we put screws into the end of the axle, it is pushing the bearing flange into the frame (instead of away from it). However, since this creates protrusions outside the frame perimeter (which are legal since they are less than 1/4” in size), we need to counterbore our bumper (also legal, as long as the strength is not significantly impacted) so that it can rest right up against our frame perimeter. Third, we are not planning on having the bumper pins stick out far below the bottom of the frame in order to prevent the robot from catching onto the bars on the ground in the rendezvous point. 

Above: The counterbore in the bumpers are shown
Above: The bumpers are shown on the chassis

Above: The protrusion outside the frame perimeter is visible

Rotary OBA

The rotary OBA was once again changed today. All of the 2 inch mecanum wheels were removed. There are now once again 2 shafts, with different spacing from each other. Finally, the pivot was changed to be a 1/2” round dead axle. 

One of the new features that is being worked on is a funnel for the ball. There were some issues with getting the mecanum wheels to center the ball. Now, they have abandoned mecanums altogether and are working on a passive funnel shape that will help to center the ball after it is captured by the rollers. 

Parallel Bars OBA

The Parallel bar OBA had some minor changes today. First, it had to be repaired after storing it. After this the shaft was re-attached. The shaft has 4 4-inch mecanum wheels as well as an omni in the middle. The other shaft further back had a roller put on it.  The roller was scavenged from the 2017 offseason, when we had put rubber tubing over some hex shaft. 

Above is an instructional video demonstrating how to put the rubber tubing over a shaft
Above: The Parallel Bars OBA repaired and with the wheel changes. 

Single Flywheel

Due to the 3d printed hood not going to be ready by Thursday (prototype voting day), we cut out a curved plywood piece as a temporary hood for now. We are currently working on installing it onto the prototype in a semi-rigid fashion so that we can push against it when we bend some thin polycarbonate to that profile. We also stole the NEO motor back from the Double Flywheel prototype (smh my head). 

Above: A picture of the new hood that we have made today. There are actually 3 of these hood pieces stacked together!

L Tunnel V2

Today, we finished making all 3 boxes. We also started working on the bars that will connect these boxes together

Quote of the Day: “The G in ‘Scissor Lift’  stands for ‘Good Idea’” — unknown reddit user

Goals for Tomorrow

Prototype voting day is Thursday. Preferably, tomorrow, we are able to

  • Finish the v2 conveyor
  • Finish installing the hood, and bend the plastic piece to it
  • Evaluate the performance of the new centering funnel