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 00:50:39 GMT
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Viewed:
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721 times
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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!
> Mine's a bit different. I use 2 RCXs. 1 controls the counterweight
> automatically - the entire platform tilts as weight distribution changes, and
> sensors detect it & move the counterweight. The other RCX is basically just so
> I can use the Mindstorms remote control to operate it! Note that the
> interaction between the two is now very different than explained on the page
> currently. I'm just putting finishing touches on the programs, I'll probably
> update the page in a couple of weeks.
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.
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.
> 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.
> <http://news.lugnet.com/loc/au/?n=4256>, but no-one else got a go, as the RCX
> programs were still in their infancy, and I wasn't 100% confident with the
> automatic counterweight movement.
:) Exactly.
>
> Regards,
>
> ROSCO
Thanks for the feedback!
Jeff
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Message has 1 Reply:
 | | Re: My Latest MOC: 1.4m Boom Crane
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| (...) 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 (...) (26 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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| (...) Here's some preliminary shots of my crane (URL)The main boom is about 1.4m from tip to hinge. The counterweight is a (...) I've had mine running to 1.8m, but while building it's been considerably shorter. I used fishing sinkers, contained in a (...) (26 years ago, 8-Feb-01, to lugnet.build, lugnet.technic)
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