Subject:
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Re: Pneumatic Arm
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Newsgroups:
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lugnet.technic
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Date:
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Thu, 16 Dec 2004 00:04:35 GMT
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Viewed:
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3773 times
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In lugnet.technic, Joseph Greene wrote:
> In lugnet.technic, Ross Crawford wrote:
> > In lugnet.technic, Joseph Greene wrote:
> > >
> > > My answers to Technic Towers O' Power and Orthogonal Bracing:
> > > Method 1- Axles, Axle Connectors and Studless:
> > >
> > > 1 square segment = 4x Constructed as follows Verticals using Axle Connector #2
> > > Alternating 90 degrees with Axle 5L between them for vertical posts, Diagonal
> > > bracing is acheived using Axle Connector #5s with Axle 6Ls between them.. pin
> > > the Connector #2's to the #5's and even without beams it's pretty sturdy..
> > > attach 11L studless (or studded) to the proturding 3L pins to further
> > > strengthen.
> > >
> > > http://68.57.255.231/lego/models/GirderTowerSegment.ldr
> >
> > That construction would be fine if the "beams" are always in compression, but
> > because the diagonals all slope the same way in each section, it would be prone
> > to twisting failure if you're not careful.
>
> Actually the only problem I encountered was a slight twist weakness in the very
> top and very bottom segments and the physical stress limits (vertically) of the
> Axles... I didn't actually reinforce it with beams at all.. looked awesome and
> handled the torque of the ~2ft boom being spun at the excessive rate of 30 RPM
> with a .5lb load... head ended up flying right off... the tower to crane head
> connection was lacking it seems...not to mention 30rpm is a touch high for a
> tower crane boom with a load at full extension.. I geared it down to about
> 3-4RPM...
> I'm still playing with the geometry to design an even sturdier config...
Yes it is surprisingly sturdy - I even built one with just #12 axles and no
diagonal bracing, and it worked very well. But they allowed significant
twisting, it wasn't enough to make them fail but I wouldn't like to push it.
http://www.lugnet.com/~469/projects/mobilecrane
ROSCO
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Message is in Reply To:
 | | Re: Pneumatic Arm
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| (...) Actually the only problem I encountered was a slight twist weakness in the very top and very bottom segments and the physical stress limits (vertically) of the Axles... I didn't actually reinforce it with beams at all.. looked awesome and (...) (20 years ago, 15-Dec-04, to lugnet.technic)
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