Build, Test, Document
Table of Contents
MSD II BoMUpdated Bill of Materials
The bill of materials will be updated throughout each phase as parts are purchased.
MSD II Risk Management
Build, Test, and Integrate
PVC Chair & Arms Cement Assembly
Using 1.5 inch PVC stock, the parts were cut in the machine shop. The tolerance was not ideal (~1/8 inches), as it was difficult to align the saw blade to the desired cutting mark.
Once the PVC parts were cut from 10' PVC stock, a dry run was performed in order to test the chair before cementing the joints together. During the dry run, a reference line was drawn across each joint to align them during final assembly. The pictures below show the assembly workstation and a complete sub-assembly.
A spare sailboat sail was used to make the chair upholstery after cementing was complete.
An initial test was conducted to determine the range of motion achievable by the 'Tractor Arm' iteration. Only one side of the steering was tested. It is assumed that both steering arms will achieve similar motion.
A table was used as the base for the sub-assembly. The dowel was attached to the table with C-clamps, which were able to securely it fairly well.
The range of motion for the tiller was estimated using a protractor. The steering arm would begin in the neutral position (180 degrees vertical) and the protractor would be used to determine the angle achieved while 'pushing' and 'pulling' with the arm.
- Both steering arms will have the same range of motion
- Tiller degree of freedom vs. Steering Arm Angle is 1:1 (i.e. if the steering arm moves 20 degrees so will the tiller)
- Chair is at an angled 5-10 degrees than what would be expected in regular use (Result of testing space)
- Upper back of PVC Chair limits arm motion of
- Chair may have to be redesigned with appropriate joints
- Foward motion achieves ~25 degrees of motion
- Backwards motion achieves ~18-20 degrees of motion
- Assume an 8" difference between current location of
the bearing and the designed location
- Bearing in picture is used as a test fixture until parts can be ordered
Test Plans & Test Results
The following document below represents the updated test plans from MSD I. A "Testing Schedule" chart was added that splits the testing phases to three distinct time frames. In addition, an engineering team was designated to carry out each individual test. A more detailed outline can be found in the official MSD II schedule.
A steering and weight test were conducted to ensure the stability of the system. These tests fall under "Minimum FOS of critical elements" in the Test Plan document linked above.
- 1 Bearing
- 1 Aluminum Sleeve
- Bearing shaft was much larger than our 1" size PVC
- Sleeve was used as filler
- 2 C-Clamps
- 2 Scales
- Lines (rope)
- Bearing is attached to side of a table with 2 C-clamps
- Sleeve and 1" arm are inserted into bearing
- 2 Scales are attached in parallel (adjacent) using lines between the leg of the table and the remaining part of the steering arm
- Steering arm is then rotated until both scales read 50 lbs (~100 lbs total) for an extended period of time
During the test, there was deformation observed in the arm, but it was not permanent. The deformation was barely noticeable, which agrees with our previous Ansys analysis of the arm (Detailed Design section).
- Cemented PVC Chair
- 2 People
- Hang the chair off of an elevated surface
- By the length and width (as seen in the pictures)
- Apply weight of one person on the very edge of the
chair in both scenarios
- For this test, it was ~120 lbs
- Observe deformations or cracks
- Note: In position 2, the chair was hung from 5, 7, then 9 inches from the table.
The initial goal of applying 300 lbs to the chair was changed to a lighter weight. This was to make the test more realistic to what the user of the chair may be. Similar to our steering test, there was deformation observed in the area where the weight was being applied to, but it was not permanent. Both weight tests passed and the Ansys simulations were proven correct.
User or Operator Instructions/Manual
- This is a video showing the assembly of the entire system, without the lines.
- This video gives a general overview of where the lines pass through the system.