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jmiller
User Rank
Platinum
Re: Design without bearings
jmiller   4/23/2012 8:55:57 PM
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I agree this wasn't an oversight.  At some point in time the overall goal changed from designing the best thing you can that will last as long as it can to, build the best thing you can that will last long enough that someone won't complain when it breaks.  I really hate that point in history.  And I am pretty sure an engineer had nothing to do with it, because we like to make things that last forever.  Until the world starts to understand that consumers will pay extra dollars for extra quality we will continue to spiral into this world of mediocracy.

William K.
User Rank
Platinum
Missing bearing breaks opener
William K.   4/23/2012 6:19:25 PM
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How about naming names? The guilty party has no defense, so they can't fight back, and perhaps if they never sold another opener, other companies would take the hint. Of course, there does exist the possible thinking that the shaft would not rotate relative to the frame, but that the sprocket would rotate on the shaft, which could serve as a sort of bearing assembly. I did have a custome motorcycle once that had a sleeve-bearing sprocket to support the drive chain on the return side so that it would not slap the frame. It never gave me any problems. Of course it did need grease every once in a while.

And I did come across an industrial machine designed by a guy named Fox, which had an aluminum arm swinging on a 1-inch steel shaft, with no bearing other than the reamed ID against the shaft. When the aluminum wore a bit the system got too loose and did not work right. The solution was a new longer shaft and two flange mount ball bearing assemblies, plus anchoring the shaft so that it could only rotate the bearings. Ifr he had elected to do it right the first time the additional cost would have been about $65 for the materials, and about 1 hour extra for the build time. The service call to fix the machine cost lots more than that, by the way.

Rob Spiegel
User Rank
Blogger
Re: Design without bearings
Rob Spiegel   4/23/2012 3:19:49 PM
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I agree, Jim. The shareholders constitute the most powerful group. If the CEO doesn't deliver a strong quarter, the shareholders can scream for his or her head. Customers can't do that, employees can't do that. Therefore, a company's management bows to the needs of the shareholders. Some CEOs can gain the confidence of shareholders and thus make some long-term decisions. But in most cases, it comes down to quarterly performance.

JimT@Future-Product-Innovations
User Rank
Blogger
Re: Design without bearings
JimT@Future-Product-Innovations   4/23/2012 12:43:53 PM
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The answer lies (again) in corporate America's disdain for the very people it employs and markets to.  To any given typical Corporation in the US today, there are three types of people:  Employees, Customers, and Stock-Holders. Employees are expendable resources; lowest on the value scale. Customers are the next highest, but not above getting beaten down if a dollar gets in the way.  Finally, the loftiest of all, is the Stock-Holder.  Amazing enough, this breed of animal is the most hypothetical of all, and cannot be clearly defined; yet is most commonly referenced in reports and announcements when the CEO has his back against a wall. "We have a responsibility to our STOCK-Holders," is CEO-speak for "I need a bigger pay-raise".  To heck with bushings & bearings.  Only Dilbert knows what they're for anyway.


Rob Spiegel
User Rank
Blogger
Re: Design without bearings
Rob Spiegel   4/23/2012 10:42:02 AM
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I agree, Chuck. Your question is the mystery that runs through many of the Made by Monkeys postings. How could they let this happen? Why didn't somebody catch this? Once they knew about it, why didn't they change it? Very simple questions. I'd love to know the answers.

3drob
User Rank
Platinum
Re: Design without bearings
3drob   4/23/2012 9:18:57 AM
NO RATINGS
I think it's pretty clear this wasn't an oversight (since it failed out of warrantee).

Somebody probably got a hefty bonus the year they decided to cut the BOM by a couple $ (look at all the money they've saved over the years).  Had the observer not been an Engineer, nothing bad would have happened to the manufacturer's reputation on discovery of this bad design.

Oh, wait.  Nothing bad has happened to the manufacture's reputation since we still don't know who it is.  But other manufacturer's also read this blog, so now they have an idea for future cost savings ...

Now I'm going to inspect mine when I get home.

naperlou
User Rank
Blogger
Re: Design without bearings
naperlou   4/21/2012 2:11:26 PM
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Careful, warren, you could get into trouble with that!

tekochip
User Rank
Platinum
Confirmed
tekochip   4/21/2012 10:43:38 AM
NO RATINGS
OK, I talked to my garage door guru and here's the story. Without naming names (I have friends that work for the company involved), the shaft routinely breaks on the chain version of the opener. If there's too large a load on the opener, like an improper or broken spring, or if the chain is too tight the shaft will start to wear. My door guru always carries a couple of repair kits for the chain version because the failure is very, very common. The belt version of the opener doesn't have the same problem even though it doesn't use a bearing either. There's enough play in the belt and the rubber motor mount of the belt version to prevent failure.


tekochip
User Rank
Platinum
Dig a little
tekochip   4/21/2012 10:03:06 AM
NO RATINGS
The door is supposed to be balanced so that there is very little load on the opener, but still, you'd think that the cycle life would dictate a bearing on the output shaft. I have a friend that owns a garage door business, so I'm going to dig into this one a little bit.


warren@fourward.com
User Rank
Platinum
Re: Design without bearings
warren@fourward.com   4/20/2012 6:20:41 PM
NO RATINGS
My mother-in-law is the heaviest object in my home...

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