Date: Fri, 08 Dec 2000 22:46:12 -0600
From: xxxxx
X-Accept-Language: en
To: kenott@uclink.berkeley.edu
Subject: ApplePBG3 Strategy

Hi There,

   I have a Pismo, and its working fine so far. I had heard about clutch problems, so I bought the extended Apple Care plan just in case. From the reports of others, I guess its not a guarantee for a free repair. I'd like to join your list, but since mine is not broke, I would be a false data point. I support your efforts, and hope that you experience success, because I think that your complaint is just, and because I too may be in your shoes! I don't know if this helps, but consider the following:

   (I'm a scientist/engineer, by the way). When you design something, one of the things you should look at is life cycle fatigue tests, to see how long something will last under cyclical loading. Very common with the automobile industry. Parts are then designed (size, thickness, material, shape, etc.) so as to last a given length of time. Some parts are actually designed to only last a certain lifetime. Some materials, like a good steel, inherently has a near infinite lifetime under cyclical loading (if its not overstressed), other materials, like aluminum, will always have a finite lifetime under cyclical loading - in inherent material limitation for aluminum. As a design engineer, you should know the inherent limitations of the materials you work with; there are all sorts of handbooks of properties for various materials. Aluminum is a good choice of material in this application, to gain weight savings, but it needs to be designed so as to compensate for its fatigue life limitations.

   Now, a hinge isn't necessarily under classical cyclical loading like an axle, but these parts are experiencing a brittle fracture after only a very short service life. This does not constitute normal wear and tear, unless Apple has deliberately designed their products to fail prematurely. A loose hinge is wear and tear. A broken hinge due to brittle fracture is a catastrophic failure (esp. if you are the part!) Its the difference between a bruise shin, and a broken leg. If we assume that on the average, the clutches are failing in 2 years with and average of 3 cycles (open and shut) a day, that comes to only 2,190 cylces. Since this is a portable computer with a screen that is designed to open and shut, and which is intended to be opened and shut several times a day, then it probably should have been designed for a fatigue life time of around 10,000 cycles, which would be 5 cycles a day for 5.5 yrs. Seems pretty reasonable to me.

   How many other hinges do you know of that fail after only being used 2,000 times? Would you be satisfied if your refrigerator door broke after only being open 2,000 times? How about your front door? If you have kids, it gets opened that many times in one day! What about the door on your car? How many car door hinges have you seen fail after only two years of use? Ok, so its a clutch, would you consider it reasonable for the clutch in your car to fail after only being depressed 2,000? That would probably be like 4 months of city driving!

   Your cause is just, and your complaint is valid. I hope you have success, and I hope my powerbook doesn't fail! Take care.

xxxxx