[Clayart] making a flat pattern for a concave surface

PETER HAMER p.hamer at btinternet.com
Sun Mar 23 18:33:18 EDT 2014


Marci,

Sorry, there is no mathematical fix. You are dealing with surfaces which have compound curvature everywhere,on the other
hand things like bent stencils cannot have compound curves anywhere. In the lingo, your decorations are not "developable 

surfaces". [A topic of some interest to people bending sheet metal, or trying to make nicely shaped boats out of flat sheets 

of metal or ply.]
Maybe you can shift from trying to apply stencils to using printing pads. If you make these out of sponge, you would only have 
to cut them so they approximately fit and rely on their flexibility for the rest.

Depending on the shapes you want, you might also try applying the image to a flat sheet, and then curving it in a "drop mould".
Should work (with some distortion) on a convex surface; not too sure about concave ones.

Regards, Peter

http://welcome.global-marcom.com/?p=113

https://www.google.co.uk/search?q=developable+surfaces&biw=1680&bih=878&tbm=isch&tbo=u&source=univ&sa=X&ei=Yl0vU62LBMW3hQet-4GACA&ved=0CD0QsAQ

http://www.youtube.com/watch?v=I5fECiiIAvw



________________________________
 From: Marci <marci at ppio.com>
To: clayart at lists.clayartworld.com 
Sent: Sunday, 23 March 2014, 16:52
Subject: [Clayart] making a flat pattern for a concave surface
 

Calling all you math guys .....
   I want to be able to make flat patterns for concave surfaces . ( specifically  Christmas ornaments ) .
  I d like to be able to make flat  templates of designs that can be transferred to the top and bottom  of the balls  ( for example ,  5, 6 and/or 8 point  " flower" shapes ) and while I can eyeball  the design directly onto the piece  and can  play with  cutting some paper trial and error ,  Im wondering if there is some sort of mathematical  way to do this . ( specifically , where to add gores so that the pattern can lay flat  to design the elements of it .. but then  fit the curvature when taped to the round piece ) ... and then possibly even made into waterslide decals ...
  Ive searched the net but havent been able to find the information  I need but Im not sure Im using the right search terms..
    Also, I slept through math class ... so talk slow and use small words  LOL ! ( If I'da known that math and chemistry were gonna be that important, I would have paid better attention instead of sketching in my notebooks.. )
Thanks, guys!
marci the chinapainter


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