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Subject: 
Re: Has anyone ever tried to design a washing machine mechanism?
Newsgroups: 
lugnet.robotics
Date: 
Thu, 27 Jul 2000 15:02:12 GMT
Original-From: 
John Barnes <barnes@sensors.com+spamless+>
Viewed: 
1032 times
  
I am wondering if you couldn't use the robo-riders container as the basis
for your drum. It has a hole for a technic axle in the lid, so, you could pass
the agitator axle in through there. You may have to do something "non-lego"
to power the drum, unless you put one of the long rubber bands around it
and drive it from a pulley. I think I had an old washing machine once that
actually worked like that!

JB


In lugnet.technic, Geoffrey Hyde writes:

The bowl itself would either have to be a special piece of material not made
out of LEGO or we'd have to wait until they produced one for us

Duplo set 2983 includes a barrel that's about 6 studs in diameter by 9 or 10
high.   You'd need to drill the bottom for the agitator axle,  but I think
that's only a "venial" sin among purists,  compared to introducing a
"foreign element"  ;-)

Other possibilities might be the 8- and 10-stud octagonal domes used in
various space and underwater models.

I hope someone has tried at least the mechanism, it would be interesting to
see how to design the rotational movement power for the washing tub changing
to a cam-based movement

I think the agitator and the tub are concentric,  but separate,  mechanisms.
Iirc,  the tub on mine is stationary during the wash and rinse cycles,
letting the agitator do *all* the agitating work.

I think cams would be a key element somewhere in
this.

They could be:  it depends on how much the agitator actually rotates.

A possibility,  if you were willing to accept a limit of,  say,  120 degrees
of rotation,  would be to put a fixed arm perpendicular to the agitator
axle (a pin in a 40-tooth gear might do this).  Then connect that arm to
something equivalent to the rod in a car engine.  At the other end of the rod
would be either a car-like crankshaft,  or a reciprocating mechanism like a
pneumatic cylinder.

The net effect is to turn the reciprocating motion of the rod into partial
back-and-forth rotation of the agitator.  The travel of the recirprocating
mechanism has to be chosen to that it doesn't swing the agitator arm through
too many degrees.  I picked 120 because it seemed fairly safe:  it
completely eliminates the risks of going full circle and of "lock-up" if
the two arms get parallel.  I *think* there's also a variation in the amount
of leverage the reciprocating mechanism gets,  based on the angular
position of the arm attached to the agitator:  i.e.,  that arm looks like a
varying-length lever to the reciprocator.  I'd have to try it to be sure,
but that's what my mental model feels like.

Ran



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