Subject:
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Re: MOC: DEMAG CC2800 Crawler Crane - Stage 1 complete
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Newsgroups:
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lugnet.technic, lugnet.modelteam
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Date:
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Fri, 11 Jun 2004 01:10:22 GMT
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Viewed:
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26 times
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In lugnet.technic, Dennis Bosman wrote:
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In lugnet.technic, Ross Crawford wrote:
AWESOME!! This is HUGE!
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Thanks Dennis! It is big, but like the real crane it can be taken apart for
transport, and no section is more than 36 studs wide or 130 studs long. And its
only about 15.5kg in that configuration.
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Im following the progress of your project since the first pictures.
When I saw the discription of your model above I thought: This guy is crazy!
He will never manage to build a 1:13 scale CC2880! Now Ive really changed
my mind :) The crane is not just big it looks great and accurate as well. My
compliments! The green superstructure gives the crane a nice look. Most model
cranes are red or yellow. Its the first time I saw a green one. You must
have bought lots of new pieces. And are most of the pieces also available in
green? I can image you have to find other solutions for specific parts of the
shape. Im curious about that because I have less green pieces.
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Yes I had to buy quite a few pieces. But mostly just bricks plates and slopes -
the green is just attached to the outside of the main structure.
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I was very pleased when I saw the swing out mechanism of the operators
cabin. The arm is four studs wide so it seems strong enough to carry the
cabins weight. The cylinders to incline it to the back are a nice feature,
well done!
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No, the arm doesnt sag much at all. However it does twist a little, because all
the weight of the cabin is on one side. For that reason there is a little
packing (folded paper) to hold the cabin level when it is lowered.
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And it is really posible to drive with it? I mean, the crane is huge so it
must weight a lot! I couldnt be truth. I built a dragline recently. This
machine has a real working undercarriage: both tracks are driven by a 9V
motor each. First I tried it with the geared ones but those were not
powerfull enough. It drives very well but the crane should be heavier. I
still have to make some pictures (I have less time unfortunately ...). I have
to put it on the net soon.
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Yes, it does drive. Its very slow, each crawler is powered by 2 geared motors,
further reduced by 1:200. And it is a little jerky. When I get the video
processed, I will post a video of it moving. The final drive is via two 40 tooth
gears, one being attached directly to one of the 24x43 wheels using liftarms.
Each 40 tooth gear is driven by two 8 tooth gears. I forgot to include details
of the drive, I will take some pics today and update the page.
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Theres one tip I can give you. I saw you used 48 teeth gears for the drumms.
My experience is the gears (or whatever) will slide when theres a lot of
stress on them. The motors needs more and more power to lift the main boom
for example. The gears will touch the inside of the superstructure.
I used webbed radar dishes instead of large gears. Because of the stress on
the cable I glued 2x2 round bricks on both edges of the Technic axle. Its a
shame I know but this is the only solution when you dont want to use other
materials than LEGO.
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The radar dishes are a great idea! Maybe even use the grey 8x8 radar dishes from
the Star Destroyer set? They may be a little big though. The other advantage of
using gears is that the power is able to be applied to at the edge of the spool,
rather than through the axle. And having 11 part line on the a-frame certainly
helps!
I havent had to glue anything yet. But Ive only attempted a small boom so far!
You can see in
this picture how I joined the 40 tooth gears on the winch, basically copied
from Bob Kojimas ringer crane. The
disadvantage of this technique is that the spool is not cylindrical, so it winds
unevenly, but its not too bad.
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And I was wondering how many metres of ropes you need :)
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Well, I havent measured exactly, but I have used most of a 100m spool of 30lb
fishing line, just for the a-frame and main hoist! I wound 50m of hoist line,
this will allow me enough for an 8 part line on a 5m boom, if Im successful.
The real crane uses 900m of hoist line, equivalent on mine would be around 70m,
so its in the ball park. The a-frame uses about 40m. The derrick will need
another 50m plus another 50m for the second hoist. Im off to get another reel
now ;)
ROSCO
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