Lessons from Poor Product Development

Vibration breaks the camel's back
The rear hatch release solenoid on Chrysler minivans is a wire-wound solenoid with one end of the wire connected to power and the other end to the metal case of the solenoid which is screwed to the hatch structure to provide a ground path. The ground end is simply wrapped around a tab on the end of the solenoid case that fits such that the wire loop is retained. But the tab has sharp corners, the wire is soft, and shock load is high when the hatch is slammed shut. So it fails. This is another case of a detail ruining a reasonable part design - the combination of using wire wrap, the tab radius, the nature of that wire (for conductivity), and the loading in that particular application does not work. What lessons can be learned here?

Pouring Coffee
Have you experienced the carafe of a coffeemaker being sensitive to spilling if tipped too far? Ever noticed that some carafe's are not sensitive? (For example, a five-year-old specific Sunbeam model is very sensitive, a three year old Mr. Coffee not as sensitive. And a newer Black & Decker model not sensitive.) I can see why the better of the first two examples isn't sensitive, from an understanding of how fluid flows - the difference is subtle but definite. (The Black & Decker carafe has a more rectangular spout, obviously different.) So, how much is it worth in product sales over the long term to spend a little extra effort to do a better job of spout design? (I don't see any difference in manufacturing cost between the first two examples, and doubt there is much in the more rectangular spout. Definitely negligible compared to the frequent redesign of the machines for styling and feature fads.)

Won't final test catch design problems?
Once I purchased a compact computer keyboard on clearance. It used a function shift key to enable page up/down (awkward), giving some letter keys a dual function. I hooked it up my computer, and discovered it had two letter keys labelled Page UP, none labelled Page DN - but the lower of the two Page Up keys functionned as a Page DN key.
How, I asked myself, could that escape the design, testing, and manufacturing system - wouldn't it be obvious?
I checked how the key was made - the letter and the Page UP were molded in, so it wasn't simply a case of the wrong label being stuck on the key. Someone had designed the mold incorrectly, probably starting by copying the information from the other key but only getting as far as changing the letter.
How could it be missed in test? Assemble the product by placing the letters in the right locations, or automatically from bins with the particular part number for the location. Then program a machine to push that key and look for the expected output from the keyboard. All seems fine to the hasty.
That's one problem with mass production - get it wrong, push the production line GO button, and thousands of units spurt out, all wrong. The economics of that are powerful!
So how do you prevent that and still be efficient?
(And I learned why the price I paid was so low. :-)

Paper Cutter fails at "Job 1"
I purchased a paper cutter. The Staples "DuoTrim" had many good features. But it failed at Job 1 - it couldn't cut paper cleanly! Duh?

Popcorn all over the place
A hot air corn popper should be easy to make, right? Wrong, not for the designers of a Toastess model, bar code 6128330197. It throws many of the kernels out before they are popped, and throws popped kernels laterally so they miss the bowl (unless it is washtub sized).
Did they test it before pushing the buttons to make thousands?
(The design has a well, at the bottom of which is a series of tangentially oriented air outlets, to agitate unpopped kernels and provide airflow to push popped kernels out the top chute. What could go wrong?

Well, in the hands of the designers of this Toastess model, something fundamental. It looks as though some kernels are popping while in the chute or beyond, having thermal inertia, even in the bowl which tends to throw unpopped kernels out of the chute at high velocity and popped kernels out of the bowl, given that the machine throws unpopped kernels out.

I am experimenting with variations in use. Using quite a bit of popcorn prevents popped and unpopped kernels from flying out except near the beginning and end of popping the batch, because popped kernels stay in the well so keep a compliant lid on the well. However, another design flaw is emphasized: as bowls are round, the popper does not have an exit lip, and the chute has no bottom, many popped kernels fall outside of the bowl (but not too far away). So if you really want to keep bothering with this incompetently designed appliance, make a light bowl of thick aluminum foil that conforms to the front of the popper and has high sides. Or perhaps you have a large deep pot with lid that you can sit the popper in, with cord running between pot and lid, or at least an oval chicken roaster pan preferabley a deep one. (Metal material is needed as unpopped kernels are hot enough to scar soft plastic material (I have not tried a hard plastic bowl).)

I suspected air velocity is too high but now doubt that. (The marketing weenies who wrote the text on the box claim it has a "unique airflow design" but the only thing I notice is slots in the back and top of the chute - slots almost large enough to let undersize kernels escape.) I wondered if the problem is more of variation in popping energy of kernels, but rejected that thesis. I considered that popped kernels can bounce within the width of the top chute such that they ricochet off the side near the exit thus move laterally at a shallow angle, and that the sides of the top cover are somewhat curved, so kernels or puffs that slide along it will have some sideways velocity to miss the bowl, but think those mechanisms are at best secondary to configuration of the well and chute (and both would be avoided by a long chute that points down into the bowl).

Corn poppers are a simple concept. The vertical configuration with outlet chute of this one is common, I've owned them before without having such problems, but there are also models with an enclosed bowl. I suspect the problem is a combination of an exit chute that is too limited and something wrong with the shape or size of the well in the machine. I looked briefly at a similar model of different brand in the store but didn't see obvious differences. (I don't remember details of poppers I've owned before, but friends recommend the Presto brand.)

Regardless, there is a basic question to be asked:
>> Did anyone test this specific design before ordering production of tens of thousands of units?

Poorly aligned switches fool user of clothes dryer
And an instance of the classic "Whirlpool Type I" clothes dryer, commonly sold as Kenmore and other brands:
- the permanent press setting has a trap. The dryer knob can be in a position that runs the motor but does not turn the heater on. The symptom is that the timer is not progressing (the desirable feature in low-price form advances the timer based on outlet air temperature to avoid overheating clothes (outlet air will be cool until clothes become drier). The user does not realize that heat is not turned on because there is action - the drum motor turns.

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Keith Sketchley's intellectual property, version 2008.06.16 (1206PDT).

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