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Subject: 
Re: My Latest MOC: 1.4m Boom Crane
Newsgroups: 
lugnet.build, lugnet.technic
Date: 
Thu, 8 Feb 2001 21:23:39 GMT
Viewed: 
228 times
  
WOW!! Thats amazing,
I'm stunned.

Gary
P.S. When do we get pictures of the cubicle devider?

Jeff Elliott <jeffe@telepres.com> wrote in message
news:3A82C528.A3B8C3B5@telepres.com...
Hi all,

Thought I'd post a photo of my latest creation, a technic boom crane.

http://www.brickshelf.com/cgi-bin/gallery.cgi?i=31827

The genesis of this MOC is that I'm building a Lego cubicle divider at
work.  Naturally, for such a large scale project, a large crane is
needed (duh! :D)  So I set about building the crane first...

The main boom is about 1.4m from tip to hinge.  The counterweight is a
1.5kg SCUBA lead weight (wrapped in plastic, of course), but that can be
doubled if I'm lifting heavy loads.

There are four controls for the crane:

1 - Turntable rotation  (1:3, 1:56)
2 - Counterweight positioning (1:24)
3 - Boom up/down (1:24, medium spool, 1:4 pulley reduction)
4 - Hook up/down (1:24, large spool, 1:2 pulley reduction)

All motive force is from single 'new' 9v technic motors, powered from a
polarity-switch / train controller setup, except the hook which is
driven off a battery pack 'cuz I ran out of polarity switches :).

The control is pretty fine once you get used to the swinging inherent in
starting and stopping so heavy an object.

Manual control of the counterweight is essential to not tipping the
crane; if you try to lift a heavy weight with the boom out, it requires
the counterweight to be moved all the way out, etc.

You also have to be cautious not to collide the erect boom with the
ductwork under the ceiling :)

I've trained two folks at the office in how to operate it; I've
sabotaged the controls  and gearing so that you need inside knowledge in
order to move it from its rest position :)

I'd be interested in discussing power and gearing solutions with others
who have developed high-load cranes... I notice that some of my gear
boxes are creating plastic dust with heavy usage, a sure sign that I
need to reconsider the gearing that I'm using.

I'm afraid I don't have much background knowledge of how cranes really
work, so I just slapped together something which functioned through
trial and error, but I'm pretty happy with the result.  If anyone has
comments on things I'm obviously doing wrong, let me know...

And if you'd like better photos, give me instructions as to what you'd
like to see; I've got a digital camera and the crane sitting on the desk
here beside me, so I can oblige easily and quickly.

Two Lego pieces were modified in the construction of this crane
(something I usually abhor):  I redrilled the two uptake spools (technic
wheel hubs) so that the threading hole would accept the heavier cord I
used.  The original hole was only large enough for thread; I widened it
to 3/32".  I guess I have so many wheels that I don't feel *really* bad
about doing this :(

Thanks!
Jeff Elliott



Message is in Reply To:
  My Latest MOC: 1.4m Boom Crane
 
Hi all, Thought I'd post a photo of my latest creation, a technic boom crane. (URL) genesis of this MOC is that I'm building a Lego cubicle divider at work. Naturally, for such a large scale project, a large crane is needed (duh! :D) So I set about (...) (24 years ago, 8-Feb-01, to lugnet.build, lugnet.technic)

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