[Oa] diagonal box roof mechanism?

[Jeff Gomes]

Andrew-

Thank you for your reply!

I have tried several different techniques.  Most of them have indeed featured string.  The one that comes the closest involves a corner-based pivot with a short section of thread linking it to the roof.

The main problem with everything I've tried so far is that, while the geometry adds up in theory, the vectors grow weak as the final position is approached.

Just like when you suspend a weight in the middle of a horizontal rope.  You can never pull hard enough on the rope to make it perfectly straight.

So, I'm thinking there must be some other geometry I'm not thinking of.  Hence the request for ideas from list members.

Thanks again for your interest.  If I ever come up with an elegant solution, I'll be sure to share it!

-Jeff

At 1026 -0700 05/02/2005, Andrew Crawford wrote:
>Hi Jeff,
>
>I don't have a copy of Paul Jackson's book and am not familiar with that particular mechanism.  Similar "diagonal box" structures I have worked with use a roof with 4 or more sides that fold up similarly to the main structure.
>
>Multi-piece structures are not my forte.
>
>Maybe someone else on the list knows this and will post.
>
>What have you tried so far?
>
>At a glance, it seems like something involving string connecting the roof on the diagonal (perpendicular to the main fold) to the main structure might be the right direction.
>
>Andrew Crawford
>
>Jeff Gomes wrote:
>>Hi everybody!
>>
>>Could someone please be so kind as to describe what the "ingenious" roof mechanism is in the house shown on page 149 of "The Pop-Up Book" by Paul Jackson.  (I have not succeeded in contacting Mr. Jackson.)
>>
>>For those who do not have the book handy, I scanned the photo and uploaded a low-res jpeg of it to <http://www.mmmagic.com/dl/om_ungers_pop-up_house.jpg>
>>
>>The text accompanying the photo says:
>>
>>"The basic Diagonal Box technique creates the simple shape of the house.  The separate roof, however, is created by an ingenious mechanism which swivels it into place and which is beautiful to watch as the card is opened."
>>
>>Thanks!
>>
>>-Jeff