Spiral spheres

<h2 data-rte-spaces-before="1" data-rte-spaces-after="1"> Building Instructions </h2>
<p data-rte-fromparser="true" data-rte-empty-lines-before="1"><img data-rte-meta="%7B%22externalImages%22%3A%5B%5D%2C%22hash%22%3A%22377de0df51895cdd679aa35aeb52c1aa%22%2C%22id%22%3A0%2C%22images%22%3A%5B%7B%22name%22%3A%22Image%3ASpiral_sphere_tiled_s.jpg%22%2C%22caption%22%3A%22%3Csmall%3ETiled%20view%20to%20show%20construction%3C%5C%2Fsmall%3E%22%2C%22link%22%3A%22%22%2C%22linktext%22%3A%22%22%2C%22shorttext%22%3A%22%22%2C%22data-caption%22%3A%22%3Csmall%20data-rte-washtml%3D%5C%221%5C%22%3ETiled%20view%20to%20show%20construction%3C%5C%2Fsmall%3E%22%7D%2C%7B%22name%22%3A%22Image%3ASpiral_sphere_top_s.JPG%22%2C%22caption%22%3A%22%3Csmall%3ETop%20view%20to%20show%20spiral%3C%5C%2Fsmall%3E%22%2C%22link%22%3A%22%22%2C%22linktext%22%3A%22%22%2C%22shorttext%22%3A%22%22%2C%22data-caption%22%3A%22%3Csmall%20data-rte-washtml%3D%5C%221%5C%22%3ETop%20view%20to%20show%20spiral%3C%5C%2Fsmall%3E%22%7D%5D%2C%22imagesShown%22%3A%5B%7B%22name%22%3A%22Image%3ASpiral_sphere_tiled_s.jpg%22%2C%22caption%22%3A%22%3Csmall%3ETiled%20view%20to%20show%20construction%3C%5C%2Fsmall%3E%22%2C%22link%22%3A%22%22%2C%22linktext%22%3A%22%22%2C%22shorttext%22%3A%22%22%2C%22data-caption%22%3A%22%3Csmall%20data-rte-washtml%3D%5C%221%5C%22%3ETiled%20view%20to%20show%20construction%3C%5C%2Fsmall%3E%22%7D%2C%7B%22name%22%3A%22Image%3ASpiral_sphere_top_s.JPG%22%2C%22caption%22%3A%22%3Csmall%3ETop%20view%20to%20show%20spiral%3C%5C%2Fsmall%3E%22%2C%22link%22%3A%22%22%2C%22linktext%22%3A%22%22%2C%22shorttext%22%3A%22%22%2C%22data-caption%22%3A%22%3Csmall%20data-rte-washtml%3D%5C%221%5C%22%3ETop%20view%20to%20show%20spiral%3C%5C%2Fsmall%3E%22%7D%5D%2C%22params%22%3A%7B%7D%2C%22type%22%3A1%2C%22wikitext%22%3A%22%3Cgallery%3E%5CnImage%3ASpiral_sphere_tiled_s.jpg%7C%3Csmall%3ETiled%20view%20to%20show%20construction%3C%5C%2Fsmall%3E%5CnImage%3ASpiral_sphere_top_s.JPG%7C%3Csmall%3ETop%20view%20to%20show%20spiral%3C%5C%2Fsmall%3E%5Cn%3C%5C%2Fgallery%3E%22%7D" data-rte-instance="2837-19952397915df1866720730" src="data:image/gif;base64,R0lGODlhAQABAIABAAAAAP///yH5BAEAAAEALAAAAAABAAEAQAICTAEAOw%3D%3D" class="media-placeholder image-gallery alignLeft" type="image-gallery" height="185" width="185" />
</p>
<ol><li>To make a member of the family, start with two types of triangles in the background color, of sizes <i data-rte-washtml="1">n</i> and <i data-rte-washtml="1">n+1</i>. For the one shown above, <i data-rte-washtml="1">n=2</i>.
</li><li>Make 4 of each and connect them at their extreme vertices. This gives you a roughly tetrahedral object with rectangular holes.
</li><li>Twist the tetrahedron so that those holes become skew parallelograms, and fill them in with another triangular grid. These are obviously curved, and the construction also slightly curves the original big triangles but this is hardly noticeable.
</li><li>The result is of course a <a data-rte-meta="%7B%22type%22%3A%22internal%22%2C%22text%22%3A%22Lobel%20frame%22%2C%22link%22%3A%22Lobel%20Frames%22%2C%22wasblank%22%3Afalse%2C%22noforce%22%3Atrue%2C%22wikitext%22%3A%22%5B%5BLobel%20Frames%7CLobel%20frame%5D%5D%22%7D" data-rte-instance="2837-19952397915df1866720730" href="/wiki/Lobel_Frames" title="Lobel Frames">Lobel frame</a>. The first illustration in this section has tiles at the original triangles, to show the basic construction.
</li><li>Now starting from one of the valence-5 balls, start a spiral in a different color (such as glow-in-the-dark). To make that as smooth as possible, you should take care where you make the transition to the next winding; do this at the skewed parallelogram meeting the valency-5 sphere with its blunt (120 degree) angle. (See the top view for details.)
</li></ol>
<p data-rte-fromparser="true" data-rte-empty-lines-before="1"><span class="placeholder placeholder-double-brackets" data-rte-instance="2837-19952397915df1866720730" data-rte-meta="%7B%22type%22%3A%22double-brackets%22%2C%22wikitext%22%3A%22%7B%7Bclr%7D%7D%22%2C%22lineStart%22%3A%221%22%2C%22title%22%3A%22clr%22%2C%22placeholder%22%3A1%7D" contenteditable="false">&#x200b;<br data-rte-washtml="1" data-rte-style="clear: both;" style="clear: both;" data-rte-attribs=" clear=all " />&#x200b;</span>
</p><p />
<!-- Saved in parser cache with key geomag:rte-parser-cache:2796 -->