Subject:
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Re: New Crane...
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Newsgroups:
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lugnet.technic
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Date:
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Wed, 9 Jul 2008 17:02:56 GMT
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Viewed:
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14218 times
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In lugnet.technic, Alvin Brant wrote:
> Well, after many dissapointments over the weekend:
>
> http://www.brickshelf.com/cgi-bin/gallery.cgi?f=328336
Ouch. That's a birds-nest mess of string you got there :-) But looks like it
faired better than my crane that decided to go down in a hurry (serious operator
error :-)
http://texbrick.com/creations/msg_50/msg50_8.jpg
> Looks like I need to stiffen up the boom a bit...
>
> http://www.brickshelf.com/cgi-bin/gallery.cgi?i=3273901
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> There sill is going to be a fixed jib added for the lifting test, and a Luffing
> jib added to try and break my previous record for height! I am hoping for 22 or
> 23 feet on this one!
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> Hope you all enjoy!
>
> -Alvin.
You're dealing with a relatively shallow boom cross section (i.e. thickness is
fairly thin compared to length). I don't think you'll see much improvement
unless you make the boom cross section thicker (deeper), which unfortunately,
you probably can't if you're keeping things in scale.
Also, you have doubled-up beams for the main chords on your boom truss, and that
is adding a lot of weight to the boom. You could probably do without
double-beams. Since you have a double boom (side-by-side twin booms), then with
single-beam main chords you'd still have 8 Technic beams as your minimum cross
section. That's plenty strong.
You might consider re-designing your truss pattern so that the joints line up on
one hole (example: http://texbrick.com/creations/msg_50/truss.jpg). But I'm
thinking that will only give you slight improvement in overall truss stiffness.
It's plastic, not steel :-)
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Message has 1 Reply:
 | | Re: New Crane...
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| (...) You mean plastic bends?? Dang :) I actually have had a good bit of success stiffening up the boom. The majority of the give in the boom was coming from the point where the sections are pinned together. The axles were flexing and letting the (...) (16 years ago, 10-Jul-08, to lugnet.technic)
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Message is in Reply To:
| | Re: New Crane...
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| (...) Well, after many dissapointments over the weekend: (URL) finally got to raise the main boom on this creation: (URL) like I need to stiffen up the boom a bit... (URL) sill is going to be a fixed jib added for the lifting test, and a Luffing jib (...) (16 years ago, 7-Jul-08, to lugnet.technic)
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