156B Week 7

Overview of Status of Analysis, Design, Fabrication, Tests, etc.

• • Designs pending:

    • spring steel compliance; thickness of steel needed

    • hard stops; crash condition on pins in SolidWorks?

Accomplishments from Previous Week

• • Puck pulley/crank pulley/airpel sizing complete; ready for order.

  • Timing belt length needed known (26" needed, but 24" and 28" available)

    • Rollers inside ruled out (~35" of belt would be required)

  • SolidWorks model reflects sponsor and professor commentary from week 6;

Goals for Next Week (list names after each item). Use specific and measurable objectives.

• • Massive parts order and more tolerance calcs (Sean)

  • Design hard stops (Mike)

  • Design spring steel compliance attachment (Tai and Alex)

  • Continue work on second rough draft of report anjd testing rigs (Steven)

  • Prepare a plate for machining/begin machining & test pulley stock for pucks (machine shop Mark)

Sponsor Comments from Last Meeting and Actions Taken to Address these Comments (indicate date of comments and if via email or in person)

• • Meeting with Ernest on 2-15-13:

    • We should go with thin lip widths of 0.040" for puck

    • Use a simple screw underneath pucks for clearance retaining

    • Since the puck has the angle-sensitive feature, hard stop needs to attach to it (not pulley stock, for example)

    • Beware of stacking two roller bearings; could use a bearing with flanged inner race.

    • Hard stop pin could just go deeper into puck

    • ALL 8 pucks need to have the same design. No special machining/assembly should be required per puck

Instructor Comments from Last Meeting and Actions Taken to Address these Comments  (indicate date of comments and if via email or in person)

• • Meeting with Professor Tustaniwskyj on 2-12-13:

    • Sandwich bearing between top lip on puck and press-fit pulley stock for interference fit on inner race

    • Spring steel can be bought from McMaster-Carr

      • Upper campus machine shop for water-cut steel

      • 1050c would work; need full-hard steel

      • MEMS High-G group (Spring 2010) for analysis on spring steel

      • Roark and Young book recommended for tapered spring steel calcs.

    • Look into Loctite for press-fit bearings

      • Option: compound 668 good up to 204C

    • Report feedback:

      • Missing Executive Summary and Impact on Society sections

      • Needs to feel more like a technical paper

      • Equation editor: essential; metric: a must

      • More figures instead of being long-winded

      • Full commentary on returned report

Risks and Areas of Concern

• • Steel pin in aluminum puck would make for less pin wear, but greater thermal expansion concerns

Resources or Information Required but not Available

• • Timing belt:

    • How to determine tension for calcs?

    • How to determine bending radius given a Young's Modulus at cold temp. and tension in belt?

Schedule

• • Describe upcoming milestone

  • Update Gantt chart.

Budget (list amount spent and amount remaining)

• • ~$885 spent (awaiting confirmation of shipping/tax amounts)

    • $33.15 on acrylic for Proof of Concept presentation prototype (Purchased 2-4-13)

    • ~$742 Boca bearings (Ordered 2-8-13)

    • ~$109 OnlineMetals (Ordered 2-8-13)

• Remainder: $2650

Progress on Report and Webpage