Subject:
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Re: My Latest MOC: 1.4m Boom Crane
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Newsgroups:
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lugnet.build, lugnet.technic
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Date:
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Thu, 8 Feb 2001 22:24:14 GMT
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Viewed:
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668 times
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Thanks, Bob,
I've taken several more pics of the crane, and uploaded them to
Brickshelf.
http://www.brickshelf.com/cgi-bin/gallery.cgi?f=3177
Some comments:
The turntable is enclosed, since it was neccessary to provide tiles for
the crane body to slide on. The base of the table is gray; the rotating
parts are red. There is a standard technic turntable in there, and it's
driven by a worm gear: you can see the axle leading in. I used
universal joints to connect to the motor since it interfered with the
crane body if I placed it in-line with the worm. The 3:1 reduction is
just to slow it down; it's plenty powerful.
There are two independent pulleys on the crane boom head, attached
between beams which are part of the boom structure proper. The opposite
two pulleys are at the back of the counterweight assembly. They
squeak...
The crane box is made of 3:4:5 triangles based on 10-stud beams (8),
12-stud beams (10) and the length of the boom beams (6). The two sides
of the boom are loosely connected via a set of 8-long crossbeams.
The larger spool is the hook take-up, and it's a supercar wheel.
The smaller spool is the boom take-up, and it's from a smaller balloon
tire.
If you look carefully at the winch pics, you can see the plastic dust
around the gearbox for the winch take-up: way too much stress.
The cable bend at the top of the frame is just sloppy; I need to make it
higher (to give more leverage when the boom is flat) and put in rollers
(to reduce friction).
The counterweight is absent in the pics; having a 3 lb weight hanging
over my head all the time seems like a bad idea :)
The extra string from the boom pulley is just sloppiness; I had too much
slack on the spool and I decided to just wrap it around the back end of
the crane since I didn't have any matches handy to cut the cord, and it
unravels very easily.
If you've got any other questions, let me know!
Bob Fay wrote:
>
> Very impressive, Jeff. Looks like you did a very good job of creating all of
> the structures required of the real thing. I like the use of axles for the
> cross bracing of the tower. That should be effective with the friction of so
> many connectors. If you get some close-up shots of the drives, I would enjoy
> seeing the detail. Thanks for sharing your creation.
>
> --
> Bob Fay
> California, USA
> rfay@we.mediaone.net
>
> http://bobfay.users5.50megs.com/
> http://www.geocities.com/Heartland/Bluffs/7900/
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Message has 2 Replies:
 | | Re: My Latest MOC: 1.4m Boom Crane
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| (...) Have you noticed the shaft with the worm gear turning unevenly (jumping)? If so it can be reduced by rotation one of the u-joints 90 deg relative to the other (so the slots line up, rather than 90 deg offset). This probably wouldn't affect the (...) (23 years ago, 9-Feb-01, to lugnet.build, lugnet.technic)
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Message is in Reply To:
| | Re: My Latest MOC: 1.4m Boom Crane
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| Very impressive, Jeff. Looks like you did a very good job of creating all of the structures required of the real thing. I like the use of axles for the cross bracing of the tower. That should be effective with the friction of so many connectors. If (...) (23 years ago, 8-Feb-01, to lugnet.build, lugnet.technic)
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