Subject:
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Re: Opening Door
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Newsgroups:
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lugnet.build.schleim
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Date:
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Wed, 16 Nov 2005 21:42:17 GMT
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Viewed:
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2653 times
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In lugnet.trains, Timothy Gould wrote:
> Dear all,
>
> I was looking at the pictures of
> <http://www.brickshelf.com/cgi-bin/gallery.cgi?f=154236 7893> today and
> noticed that it's doors open by using droid arms as hinges. I wondered if
> such a technique could be employed in a train an found that yes it could...
> but with limitations.
>
> My first attempts were to use just one set of arms to make the door. This
> proved vaguely possible but gave a really weird opening shape so was not very
> good.Eventually I settled on an approach using two sets of arms so that the
> door looked like this
> <<http://www.brickshelf.com/gallery/timgould/temp/swingingdoor.png>>
> <http://www.brickshelf.com/gallery/timgould/temp/swingingdoor.mpd MPD>
>
> This solution is satisfactory and opens quite well but I can't help but feel
> that a better solutions should exist employing only one set of droid arms. As
> such I'm asking all the SNOT masters on Lugnet to try to find a better
> solution, preferably using only one set of droid arms. Hopefully someone will
> come up with something good. I feel that one plates height (8LDU) can be
> taken from the door and it will still look OK (in fact the gap might look
> quite good).
>
> A quick word of warning to CADders, these solutions will often puch the Lego
> tolerances to their limits so I seriously suggest using real bricks to test.
> Some of my early designs seemed fine in CAD but were just off in the brick.
>
> Hope you enjoy the challenge and I'm sure someone can come up with something
> good.
>
> Tim
There are two key differences between the plane and your solution:
1. The plane's door is a lot thinner and does not require movement in one
straight direction at 90 degrees to the body as your train door does for the
first 1L of opening movement.
2. The positions of the pivots are different, the plane having its door pivot
further inside the body when closed and the body pivot 0.5L from the outside of
the body.
Given these two differences, your solution of 4 droid arms for the train is
good. In order to get away from two sets of droid arms (or a three-pivot
mechanism with other parts) you would have to eliminate the need to move the
door straight out for 1L before moving sideways. This would require a door no
thicker than 1 plate, with the SNOT facing outwards rather than along the body,
which creates problems for your door window scheme.
As an alternative 3-pivot scheme with fewer droid arms, could you incorporate a
green 1x2+1x4 bracket http://www.bricklink.com/catalogItem.asp?P=2436 or a green
1x2+2x2 bracket http://www.bricklink.com/catalogItem.asp?P=44728 into the door,
with a 1x2 hinge brick http://www.bricklink.com/catalogItem.asp?P=3937c01
mounted on it (2L high and 1L wide orientation), holding the piece with the rod
cross section http://www.bricklink.com/catalogItem.asp?P=2540 for the droid
arms? That might give you just enough freedom of movement in the 3rd pivot to
allow you to eliminate 2 droid arms.
Alternatively, buy a few Fenris Wolf Viking sets - they have lots of black droid
arms!
Mark
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Message has 1 Reply:
 | | Re: Opening Door
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| Hi Mark, (...) However if we reduce the width of the door by one plate as I suggested we free up the 90degree requirement (which is why I suggested it). As such, I can't help but feel that a dual pivot solution should be available. (...) Hmm, I (...) (19 years ago, 16-Nov-05, to lugnet.build.schleim)
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