Day 7 – Design Review Meeting (1/11/2020)

Authors: Andrew Georgioff, Ritik Mishra

2 Inch Vectored Intake Wheels

Yesterday, we finished assembling our first 3d printed 2 inch vectored intake wheel as a test. Today, now that we know how to assemble them, we assembled 7 more of them to be used for different intake prototypes.

Rotary OBA with 2 inch vectored intake wheels

Now that we have many 2 inch vectored intake wheels, we were able to make more progress on our rotary OBA prototype. We tested 2 inch vectored intake wheels with our rotary OBA and while they managed to vector the ball to the center, only one row of wheels struggled to fully intake the ball. We decided that a solution for this would be to add a second shaft further out with more 2 inch vectored intake wheels to make it easier for the ball to move toward the center. 

Design Review Meeting

We had our second design review meeting with the design committee. This meeting was aimed at critiquing our current prototype designs and had two purposes. First, we wanted to brainstorm improvements in our prototype designs. Second, we wanted to get an idea of which prototypes may see the most success. To accomplish this we ranked them by factors such as size, weight, speed, and overall effectiveness using input from both the design committee and the overall team.

Below are the rankings from the meeting.

Single Flywheel

There were 3 major improvements made to the Single Flywheel design today

  1. A proper hood was created out of curved parts of 3/4” plywood each
  2. The 3D printed belt pulley that had stripped out was replaced with a metal adapter (more on that later)
  3. The compression was increased from ~0.5” to 1.5” 

It shoots quite fast now. 

Next steps include

  • Doing some physics-y stuff (e.g measuring ball speed, true ejection angle, moment of inertia, etc)
  • Tuning it for accuracy
  • Testing it on the real Power Port (thank you Eric for making it! <3) 

Double Flywheel

Today, we finally added the NEO brushless motor to the double flywheel prototype, allowing us to test it at full speed. We also made another one of those adapters for this prototype. It works great!

Next steps include giving each wheel a separate NEO motor so that we can investigate how a difference between wheel RPM’s impacts ball spin.

The last turntable

Upon testing our turntable prototype before the design review meeting, the friction between the ball and the inside of the cylinder was so large that the wood screws connecting the fin to the pentagon came out. 

At the design review meeting this evening, we decided that a turntable would be a lot more work than it would be worth because the balls were too grippy. 

Homemade 8mm keyed shaft to 1/2” hex shaft Adapter

So I’m really proud of how the metal adapter turned out. 

All I needed to make this is a size O drill bit, the drill press, a short segment of hex shaft that had a small (preferably #7 or .25”) hole pre drilled in it (ideally the hole is on center and was made in the lathe), a #7/.25” drillbit, and the keyway broach set we have. Preferably, you’d do this on the lathe, but I was unable to use it at the time. 

Instructions for manufacture:

  1. Drill out the center hole to a size O
    1. In a drill press however, you must first ensure that the shaft is perfectly straight. Put a drill bit into the drill press that is the same size as the hole already in the shaft, and put it all the way into the hole while it’s off in order to align the shaft
    2. Make sure the shaft and its vice are clamped down well. Additionally, ensure the table won’t rotate around
    3. Switch the drillbit to size O (approx. 8 mm) and drill it out
  2. Use the keyway broach set (we actually own one!)
    1. You’ll need the 5/16” guide bushing and 3/32” broach. These will be close enough for you but will not be extreme precision.
    2. Follow these instructions:

This way, you can save 10 dollars because you won’t have to buy a 10 dollar adapter off the internet. Granted, if you need a mechanism to be precise, it may be worth the 10 dollars and the shipping cost to buy it.

Quote of the day: “How many quarters are in a football game?” — Donovan Maas, Former Programming Lead (2017) and Current Alum