[Oa] Re: Swivel Roof Mechanism

[Jeff Gomes]

Frank, et al.-

Birmingham's book arrived today.  I'm glad I bought it, because it has many useful details in it.  So thank you again for the recommendation.  Alas, the book does not seem to solve my current challenge.

Mechanism #49 is close, but the author tantalizingly stops right where this one gets interesting.  I have tried this approach previously, with the addition of little thread tethers to snug down the eaves as the walls reach their fully open rectangle position.  The house itself worked great until I attached the whole works to the base page.  Then I discovered the problem.  Having the roof anchored at the gable ends forces the eave corners closest to the v-fold to crash into the card as it is closed and opened.

It appears that, if the ridgeline is to be the point of attachment, the two halves of the roof need to fold UPWARD to get out of the way when the card is closed.  I worked out a geometry that does this in theory, and constructed it using Selena's integral roof beam idea.  I have uploaded a PDF pattern for it to <http://www.mmmagic.com/dl/house_exper.pdf> in case anyone is interested.

The motion looks very pretty (to me, anyway!) while the card is opening and closing.  Unfortunately, it tends to leave a large gap between the eaves and the side walls when the card is fully open.  This is because of the constraints imposed by materials (or my lack of skill at manipulating them) and the vector power issues I mentioned in earlier messages.

My next experiment will concentrate on using the same or similar geometry but trying to optimize my construction techniques to make the hinges less resistant, etc.  And I'll try to get some pictures this time around.

-Jeff

At 1401 -0700 05/06/2005, Jeff Gomes wrote:
>Frank-
>
>Thank you very much for the recommendation.  I have searched in vain for this book in all the libraries in my area.  I shall have to buy it.
>
>-Jeff
>
>At 0010 -0400 05/06/2005, Fjmxcels at aol.com wrote:
>>Andrew/Jeff/Selena
>>
> >I would like to suggest you take a look at Duncan Birmingham's book Pop-Ups! A Manual of Paper Mechanisms. In particular, Mechanism #49 (Pop-up  House) p.44 and possibly Mechanism #77 (The Double 45 Degree Fold) p.66.
>>
>>I believe #49 describes in picture and detail something very similar to what you were describing, Selena. #77 may hold the key to the "very intriguing twist mechanism."  I hope this might help or give some ideas.
>>
> >Frank Miller (An OA enthusiast and designer...but not well published)
>
>...