Donut/Doughnut fun!

Mon, 21 Jun 2010

I received the by now traditional Simpson socks for Father's day and as you would imagine, this got me thinking about doughnuts. A quick search on google turned up nothing by way of toroid nets. Time to get the brain into gear. I had a vague memory of a toroid shape made up of sections in an advert for Mathematica, but how to design the section?

Each section is a kind of circular wedge. The net for that would have a sine wave edge. So, create sine wave, sample 360 degree section of same, stretch to appropriate size.

I then flipped over a copy, added evenly spaced vertical sections (8 of them) and created the net for a single section complete with tabs that you see above.

It worked surprisingly well! Notice that even though the edge is based on a curve it sits nice and flat on the work surface. Lovely.

There is a certain amount of guess work involved here. How steep should the angle of the wedge be? How many sections will I need? These two numbers are connected but I'm not sure how. Time to cut out and try.

I glued six sections together and created this shape which looks like it is just short of half a doughnut.

Too save time and cutting, here is the same shape held up to a mirror. Two more sections I reckon, making fourteen in total. I'm really not sure how I'm going to glue the last piece into place!

Fourteen seemed like a lot of parts so I tried the same again but with much thicker wedges. The result is in the square photo at the top. Looks like seven wedges for a complete shape . Looking at it, though, I think the fourteen wedges are worth the extra effort.

Colour and sprinkles next!


I've added the file with the parts as they are so far if you want a try. Member's download below.

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Comments (3)

  • mavzb June 22, 2010 at 8:01 am

    Hi Rob,
    How steep should the

    Hi Rob,

    How steep should the angle of the wedge be? How many sections will I need? These two numbers are connected but I'm not sure how.

    360 ÷ number of sections = angle of wedge

    (or equivalently 360 ÷ angle of wedge = number of sections)


    [Edited to add]

    There is a completely different style of net for a torus at HomespunMagixx

    • robives June 22, 2010 at 10:02 am

      Duh! Oops. And I can work out

      Duh! Oops. And I can work out inner and and outer radii from this as well.

  • William Hornbaker June 22, 2010 at 6:42 pm

    Closing/gluing the last

    Closing/gluing the last joint(s) can be accomplished by leaving extra tab material on one of the pieces and gluing the two tabs  turned inward together.

    Alernatively punch one or two 1/4" holes close to the last tabs to be glued and use a stick or wire tool to press the glued tabs to close the torroid.

    The HomespunMagixx suggested by 'mavzb' above is more fun and eyestrain than I care to enjoy!  🙂

Comments are closed.