156B Week 5

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

• • Most 3D printed parts are finished and assembled

  • In progress of deciding whether to use solenoid or rack & pinion

  • Redesigned the straw stopper with spring

  • In progress of ordering more parts through amazon and McMASTER

  • Performing smearing tests to determine the optimal speed

Accomplishments from Previous Week

• • Got the stepper motor to work

  • Made improvements on the slide holder platform

  • Used the functioning linear actuator to test smearing (held straws manually)

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

• • Straw stopper spring mechanism implementation -- Guanhao Fu

  • Linear Actuator control code perfection -- Yi Cui

  • Pressing mechanism redesign -- Lumei Xue

  • Device fixation brackets -- Yuhui Shen

  • Rotation prevention -- Ruiqi Wang

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

• • Plan to meet with sponsor on Friday.

  • Only update them when there is significant progress.

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

• • Need to figure out a way to cut straws evenly. This device can be separate from the smearing device.

  • For the straw cutter, we could employ a V-slot that fits for straws with different diameters.

  • Design a container to store straws

  • Risk and Concerns: good control?

    • Need a spring for precise control of force: coil spring. Forces does not change much when distance changes a bit. This might be done by attaching a spring to the rack.

    • Stepper motor for steady control of distance.

  • How to deal with a rolling straw? Blood on it can cause problems.

    • Increase friction between them, for example using rubber or sandpaper. Need to look up the coefficient of friction of straws and find the range of it.

    • Use a sharp thing to puncture the straw to prevent rotation. But then it would be hard for the straw to fall.

  • An alternative option for pinion and rack is crankshaft.

Comments from Other Students in the Class (indicate date of comments and if via email or in person)

• • None

Risks and Areas of Concern

• • Contamination on the edge of the part

• • Rack constraint is difficult to be implemented

  • Spring attachment on the tip of the rack

  • Spring attachment on the straw stopper

Resources or Information Required but not Available

• • None

Schedule

Budget (list amount spent and amount remaining)

• • Amount Spent:

Progress on Report and Webpage

• • Finished draft of report by Friday