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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Fri, 9 Feb 2001 01:14:33 GMT
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Viewed:
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2052 times
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In lugnet.build, Jeff Elliott writes:
>
>
> Ross Crawford wrote:
>
> <snips galore>
> >
> > Hi Jeff, great crane!
> >
> > Here's some preliminary shots of my crane
> > http://www.lugnet.com/~469/projects/towercrane
>
> Heh heh, yeah, I've seen those... they and Dennis' enormous crane
>
> http://www.geocities.com/dennisbosman/bmnr04.html
>
> were my chief inspiration when I built my crane. Hats off to both of
> you!
Thanks! But I don't think I'll ever get close to Dennis' creations. I
definitely tilt in the direction of functionality! As for height, each of my
tower sections uses a lot of pieces, so even though I'd love to challenge his
4.2m, I don't think I'll be able to.
> I thought seriously about using the RCXs to auto-control the
> counterweight, but I wasn't sure exactly how hard it was to control, and
> I have yet to make a computer program that has better feedback control
> than I do... I was afraid of catastophe until I knew more about the
> crane.
My current system works fairly well - I'll explain in detail when I update my
page.
> I'd love to see more detail of how you built your feedback sensors -
> I've been playing with designs in my mind, but I wasn't happy with any
> of them.
Coming Soon!!
> > I need 2x old 9v for rotation, as these motors seem a lot "weaker" for the • same
> > speed than the new ones (this may be friction related). Because of the • weight
> > of the platform, the friction generated at the edges of the turntable was
> > excessive, especially when it's slightly off-balance, so I used some • margarine
> > to help it along!!
>
> It's the gearing down... the friction takes a lot out of the motors.
>
> Do you find that having the hinge point *behind* the turntable
> negatively affects stability at high boom elevations? Or is the boom
> simply not deisgned to go that high? I found that with the boom mostly
> vertical, I couldn't move the counterweight in close enough to make the
> system stable unless a large weight was on the boom. I would expect
> that moving the hinge back would exacerbate the problem.
It is a problem, and I've actually moved the hinge closer to the turntable
since those shots were taken, but still can't raise the boom all the way
without a load. And I can only lift fairly small weights (like a couple of
technic beams) at the maximum radius of 1.8m.
Regards,
ROSCO
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Message is in Reply To:
 | | Re: My Latest MOC: 1.4m Boom Crane
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| (...) <snips galore> (...) (URL) my chief inspiration when I built my crane. Hats off to both of you! (...) I thought seriously about using the RCXs to auto-control the counterweight, but I wasn't sure exactly how hard it was to control, and I have (...) (26 years ago, 9-Feb-01, to lugnet.build, lugnet.technic)
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