Fall 2017, Week 7: Final Design Decisions

As we near the start of the rapid prototyping stage, our team must still finalize a few designs. First of all, to clear the gap of the switch, my team and I designed the switch assembly in the figure below.

To overcome the clearance gap of the switch, we decided to introduce a third rail. This third rail consists of three portions: the straight rail which inserts into the switch bracket attachment (in blue), the curved rail, and a wedge, used to support the curved rail. The assembly also needed a middle bracket to support all the weight present around the wedge area; thus, the middle half bracket was created. This geometry was chosen because our team wanted to avoid mounting anything onto the curved area.

The entire 3D model for this track is near completion, but our team is still considering options for how to mount the support beams and brackets. Our hope is to complete this by next week, so that a test model can finally be fabricated. 

Fall 2017, Weeks 5 and 6: Further Design Work

After completing Presentation 1 of the semester last week, the 1/12 scale team continued further design work for the new track. To tackle the problem of the switch rail, I first calculated the minimum curve radius of the turn. With an assumed front axle rotation of 20 degrees, I found that about an 11 inch curve will allow the bogie to run smoothly. Below is one design option for the switch.

To guide the switch, we are currently revising the idea I had a couple weeks ago. The gap that the bogie must clear is longer than I anticipated, so I decided to go with another design.

By next week, my team and I hope to have a complete Bill of Materials, as well as a concrete solution to supporting the track.