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Made by Monkeys

Key Redesign Spells Trouble for Mower

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ChasChas
User Rank
Platinum
interlock
ChasChas   8/23/2012 4:39:32 PM
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This spade connector "key" appears to be a safety interlock for charging. (Pull out the jumper and plug in the charger cord.) There is another way to turn the machine off and on.

Still a poor way to do it.

BillyMoore
User Rank
Gold
Re: Cheap Design
BillyMoore   8/23/2012 4:22:00 PM
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I've gone through all types of string trimmers.  I've had a gas trimmer, battery powered, and electric.  The battery & electric units were both cheaply made and poorly designed with no means of repairing.  Once they break, they're done.  The battery powered unit had the brushes go bad, but the case would not come apart without destroying it.  I've given up on using electricity for outdoor power equipment, and that's coming from an EE.  To get something that's maintainable with a dealer network, I've gone back to gas power for all my outdoor equipment, and that's a shame.

Larry M
User Rank
Platinum
Re: Toggle switch?
Larry M   8/23/2012 4:09:11 PM
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Well, those coaxial barrel connectors are used for 100 watt laptop supplies. Given that their output voltages range from 16-20 volts, they ought to be good for 5 amps. And people hot-plug them all the time and I've never heard of any damage.

I thought about conduction/arcing/sparking during insertion and concluded that there must be another trigger on the handlebar that starts and stops the motor--you wouldn't want to extract and re-insert the key every time you find a branch on the lawn and stop to throw it aside. That trigger takes the brunt of the motor stop/start and, if properly designed, has a flyback diode across it to prevent contact damage.

Monkeys might forget the flyback diode.  Chrysler forgot on the power door locks of my 1985 Caravan. They omitted the one on the air conditioner clutch too--the retrofit was a really crude fix. The diode was piggybacked on the spade connector to the clutch and covered with heat-shrink tubing which continued to shrink due to underhood temperatures until the diode was completely exposed.

realtrains
User Rank
Iron
Re: Toggle switch?
realtrains   8/23/2012 4:00:53 PM
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I am not sure if this key simply enables the running or directly starts the motor.  If the latter, then connector contacts are not typically rated for connection under load while a switch is.  p.s. I hope the switch used was rated for DC use or it may weld shut and make the motor impossible to stop.

 

uniquity@uniquitypsych.com
User Rank
Gold
Re: Cheap Design
uniquity@uniquitypsych.com   8/23/2012 3:56:40 PM
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I too have had a recent Black & Decker problem.  I needed a new corded string trimmer.  I tried to to research on the internet by looking at owner reviews.  There were lots of problems with older B&D trimmers regarding a plastic gear failing.  Since there was a new model number I did some checking, and it appeared that B&D had paid attention to the problem.  There were also comments about this trimmer using lots of cutting line.  Some people had devised a method of getting around the constant changing of the spool. 

So, I went ahead an bought one.  No pully problem, but it does go thru trimer line like crazy.  This unit has a very strong motor, and it might need a heavier line.  But B&D makes it clear that the line they specify is the only size to use.  I am afraid that if I go to a heavier line it will burn up the motor.  I don't use the auto fee spool, but I cut a piece of line and loop it around the center post in the head.  It still breaks at least one side very frequently.  I am not sure, but I think the machine is made in China, not the USA. 

When it works, it works great.  I do not think that a well designed machine should use trimmer line as fast as this one does.  I really do not know what the problem is, and I do not have a solution.  As an older person it is nice to get the frequent breaks in the work of trimming.  I just would rather have them when I wanted, not when I had to change the trimmer line.

I have used other brand trimmers, and they do not go thru line so fast.  They have also not held up that well.  Perhaps the only answer it to start using hand tools like in the 1950's.

realtrains
User Rank
Iron
Re: Cheap Design
realtrains   8/23/2012 3:56:23 PM
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This is not always done due to cost considerations. Many consumer products are designed by persons, I may not want to give them the title of Engineers, that have limited experience. Add a fear of looking bad by showing it to others, and lack of formal design reviews and you get this.  It takes hard won knowledge to be able to quickly think through all the options and select the best and others may still add to your work.  Given design in a computer without any actual testing and production ends up making this.

Larry M
User Rank
Platinum
Toggle switch?
Larry M   8/23/2012 3:46:18 PM
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Why bother with a toggle switch? Why didn't you simply take a coaxial plug (barrel connector) and solder the two contacts together? And of course you must have fitted the charger with another barrel connector, right?

Rob Spiegel
User Rank
Blogger
Re: Cheap Design
Rob Spiegel   8/23/2012 2:28:55 PM
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I have always had good luck with Black and Decker products. But I haven't purchased any new B&D products in recent years. The old ones have been working fine for a long time. I would be another heartbreaker to find you can't count on this brand any longer.

loadster
User Rank
Gold
Re: Cheap Design
loadster   8/23/2012 11:09:36 AM
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You gets what you pay for. Alot of posts seem to have communication errors and I wonder if this is another one. I looked at B&D product line and I didn't see a mainstream 28 VDC mower. Did you mean 36 V? And I guess this is a safety key? Its supposed to be useable by authorized, competent hominids with dexterity. Maybe the safety aspect was excluding you?  Perhaps you should look into the Roomba line of autonomous mowers and take the human out of the operating loop to the greatest extent. Sorry but it is B&D, and though they started out as good quality USA made tools, they've been beaten down by the imports and now much of their stuff goes to the landfill everyday and is repurchased from Mallmart stores at equal flow-rate. So it goes in our red-white-blue economic model of gross consumption and disposal. Good luck with your field modification; hope it serves you well.

Scott Orlosky
User Rank
Platinum
Cheap Design
Scott Orlosky   8/23/2012 9:54:09 AM
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I know engineers are continually tasked with developing low cost solutions to designs, but I have to agree, this is just plain cheap.  Expecially so, since there are so many proven design alternatives available.  B&D used to be considered a quality brand - seems that they have had a change.

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