Subject:
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RE: running the motors underwater
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Newsgroups:
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lugnet.robotics
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Date:
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Sun, 2 Jul 2000 13:07:58 GMT
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Original-From:
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Leinhauser, Phil <phil@*avoidspam*delconet.com>
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Viewed:
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734 times
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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 pressurized. If the motor didn't have these vents, you
could potentially damage it from the pressure inside that would develop.
Also, something else to keep in mind. If your motor is running for a bit,
then you put it in the water, that nice warm motor that you just cooled off
by putting it in the water, will take a big gulp of water as you cool it off
and that expanded air now contracts.
Something you could look into would be somehow bagging the motor with a thin
plastic bag. Almost a material like "Glad Wrap". If it was thicker, you
might not be able to snap the legos together. The action of snapping them
might pinch the plastic to the point of loosing the seal though. I haven't
tried this, but just thinking out loud.... Then there's how to get the
spinning shaft out of the bag while staying sealed. If the shaft were round
you could use a rubber band to hold the bag shut over the shaft but loose
enough to let the shaft spin. Some vaselene would help the seal and lube
the "bearing".
Phil
-----Original Message-----
From: news-gateway@lugnet.com [mailto:news-gateway@lugnet.com]On Behalf
Of Ben Erwin
Sent: Thursday, June 29, 2000 6:44 AM
To: lego-robotics@crynwr.com
Subject: running the motors underwater
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 2 Replies:
 | | Re: running the motors underwater
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| Are your tank filled with salt water? What is the electro-conductivity of your water? By the way, sinking a motor under water will damage lubricant inside the motor. I suggest you to pack the whole mechanic into a metal case, and seal the metal case (...) (24 years ago, 2-Jul-00, to lugnet.robotics)
| | | Re: running the motors underwater
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| Hi, I followed your underwater thread with interest. Today I noticed an underwater motorized propellor unit in the '99 Playmobil Add-Ons catalog. It might be adaptable, try (URL) and search for 'underwater'. Price: $5.59. It is a 1.5V motor and (...) (24 years ago, 15-Jul-00, to lugnet.robotics)
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Message is in Reply To:
| | running the motors underwater
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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 (...) (24 years ago, 29-Jun-00, to lugnet.robotics)
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