Subject:
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running the motors underwater
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Newsgroups:
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lugnet.robotics
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Date:
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Thu, 29 Jun 2000 10:44:09 GMT
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Viewed:
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629 times
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A few years ago some kids I was working with were trying to outfit a LEGO boat
with a paddle wheel and micromotor. While they were working, one kid got the
idea that he was going to put a propellor onto one of the 4200 rpm motors, add
wheels, and have it drive around the bottom of our water tank. He used LEGO
weight elements to make it sink.
Somewhat to my surprise, the thing worked. The wire was connected to one of
the 9V battery packs, which remained above water in his hand as he drove it
back and forth. (and then he would make it rise to the surface and splash
everyone -- that was the end of that game)
So about a year ago or so I decided to try a similar thing with the gear
motors and the RCX. Except this time I had read a book about underwater
robots, and i really wanted to make a sub. To make a long story short I have
a working underwater submarine, with the motors are exposed to the water, and
it works.
I told some people at Mindfest about this and they were pretty shocked that
the motors would work underwater. Well... they do... for a while... and I had
fun making the thing drive around my industrial size sink, do turns, etc...
But I have had motors resurface and then the axle makes a little noise when it
spins... or I've had them seize altogether.
Needless to say, I haven't played with the sub much.
QUESTION STARTS HERE:
But I was wondering if anyone has done any experimentation with blocking up
those holes at the back of the top of the gear motor and doing underwater
tests then? These are the holes that allow you to stick in a small
screwdriver and pop off the back panel (which doesn't do much good). Do these
holes serve any purpose? i.e. if they help cool the motor or something than
perhaps I shouldn't block them up with silicon?
Curious,
Ben
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Message has 1 Reply:
 | | RE: running the motors underwater
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| I have run the Lego motors for long enough that they have gotten warm. This tells me that the holes you want to plug up would be needed as air vents. Not as much for circulation, but to let the air in the motor escape when it heats up and becomes (...) (24 years ago, 2-Jul-00, to lugnet.robotics)
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