GM3

Memo

To:        Gene Hacker, Wired Bliss LLC

From:    GM^3

CC:       Dr. David Hartman

Date:     4/28/01

The progress made by GM^3 since February 25, 2001 is as follows: we have scraped the original umbrella cam design and replaced it with a constant angle cam design, designed the cam lobes for the new design, started finite element stress analysis on the new cam lobes, and researched machining processes.

The umbrella cam design was scraped because analysis showed that the usable range of the anchor is  too small for practical applications.  This is because as the arms are expanded or contracted the angle between the normal surface of the crack and the line of force changes.  As a result the friction force changes.  This changing angle and force limits the range of the cam to 0.6 cm, much to small for practical use.

As an alternative to the umbrella cam we are optimizing the standard logarithmic curve cam.  The logarithmic curve will give a constant angle (camming angle) between the normal surface of the crack and the line of force application.   The camming angle we are using is 14.5 degrees.  The current cam lobe design is shown in the attached drawing. 

Finite element analysis of the new cam lobe has begun.  The geometry and meshing of the cam lobe has been entered into COSMOS (the FEA software we are using).  However because of some of the quirks of COSMOS the model has not yet been solved. 

We have begun research on manufacturing processes for the new cam.  We have located computer software to convert an AutoCAD drawing file into machine code for a computer numerical controlled milling machine.  We are also researching connection techniques for the load bearing cables.  In order to reduce construction time and cost we will utilize the cables, axles, bushings, springs, and trigger mechanisms that are already used on a Wired Bliss #4 cam.

Please note this project has been changed from a clean slate design to a design modification.

The capstone design conference will be held on April 20, 2001.  This gives us three weeks to finalize the design, build the design, and test the prototype.  Our immediate goal is to finish the FEA analysis.  This will be completed by Monday April 2.  The following week we will finalize the design, purchase materials, and generate the CNC code.  The week before the conference we will construct the first prototype and test it to failure.  Additional prototypes can be constructed as desired, however they will probably will not be available for the capstone conference.

Visit our web page at http://www.cse.nau.edu/Design/D4P/EGR486/ME/00-Projects/cams   

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