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Subject: 
Re: A Beautiful Machine prototype and perhaps a challenge/idea
Newsgroups: 
lugnet.robotics
Date: 
Thu, 11 May 2006 21:49:51 GMT
Viewed: 
2007 times
  
Danny Staple wrote:

In lugnet.robotics, Rafe Donahue wrote: • <snip>

I like your version, first its more cute and friendly, and secondly you can see
the workings. I take it that when powered off, the scissor lift retracts again
under its own weight as the motor offers no resistance?
<snip>

It is slightly more complicated than that.  In order to make it go up
slow enough to be interesting, I had to gear down the speed of the
motor.  As such I go from 8 teeth (I think) on the motor to the big 40
(?) teeth on the scissors.  There is still some resistance in the motor
that is then increased when the scissors retracts because during the
retraction the gearing goes big to little.

So the trick was to use one of those wind-up motors.  Enough energy is
put into the motor while the scissors is going up so that the wind-up
motor can get it going to fall back down.


I am just having a thought that the polarity switches could be used to divert
the voltage from the retracting motor to another motor using the "magic motors"
technique, which has much less mechanical resistance to overcome, and is set up
to turn the machine on again, then it could actually be turning itself on again
as well - setting up a kind of amusing cycle. Are you using a 9v gear motor in
this?


If I understand what you are saying, that would be fun to watch.  My son
cracked up at the thought of a chain of machines each turning on the
next one; the longer the chain, the longer the cycle.

I am using the 9v motor that comes with the RIS set; is that the one you
mentioned?

I found it quite surprising actually that there was not much
gravitational potential energy in the scissors when it was at the top.

Anyway, it's fun to have it on the little table in the entryway of the
house:  Walk by.  Hit the switch.  Watch it run.  Don't worry about
forgetting to turn it off!

Rafe



Message has 1 Reply:
  Re: A Beautiful Machine prototype and perhaps a challenge/idea
 
(...) Very nifty! Another way would be to have a second switch that is on except when the scissors are at the bottom, and wire it in parallel with the activation switch. Sorta like how they get car windscreen wipers to always go back to the right (...) (18 years ago, 11-May-06, to lugnet.robotics)

Message is in Reply To:
  Re: A Beautiful Machine prototype and perhaps a challenge/idea
 
(...) Very interesting, if a rather disturbing implementation. I had heard of the conecpt, but not seen those vids. The prosthetic is just a big creepy. (...) I like your version, first its more cute and friendly, and secondly you can see the (...) (18 years ago, 11-May-06, to lugnet.robotics)

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