# Sketchup Question



## noddy67 (9 Nov 2011)

I'm trying to draw a design for a pedestal which involves having one larger icosagon (20 sided) board approx 600 mm directly above another slightly smaller icosagon, with the upper's midpoint directly above that of the lower one.. On each of the 20 sides will be a slat attached that will be wider at its top than at its bottom. The problem I'm having is that when I draw the slats freehand in sketchup I'm unable to get the four sides to make a face and therefore can't use the push/pull tool. I suspect its because they are in a diagonal plane. Is there any way I can force the for slat sides to make a face? 

Many thanks


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## DonJohnson (9 Nov 2011)

Are you drawing lines for all 4 sides of the slat?

I know the sizes are wrong, but I produced this without problems - but getting the edges to match may be another matter !!!!

http://www.donjohnson24.co.uk/projectpics/icosagons.skp


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## SketchUp Guru (10 Nov 2011)

How are you making the icosagons? If you are using the Polygon tool, make sure youu drag the radii for both out on axis. If you don't, the edges won't be parallel and the lines you draw between them won't be coplanar. To get the face to Push/Pull as Don shows, those edges must be coplanar. You can test this by drawing a diagonal between corners. If you get triangular faces, you can be assured that the perimeter edges are not coplanar.

Here's an example. On the left the icosagons are drawn so their vertices align and getting the face is no problem. On the right, the top icosagon is rotated 5 degrees and it takes the diagonal to make two triangular faces because the edges are not coplanar.


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## noddy67 (10 Nov 2011)

Thanks very much indeed guys. When I made the icosogons they were indeed rotated slightly. Amazing how often that coplanar issue gets me.

Much appreciated.


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## SketchUp Guru (10 Nov 2011)

It's good way to learn your basic geometry. 

One thing that will help you avoid problems is to make sure you always drag out the radius of any circle or polygon on axis. If you always do that you shouldn't have any difficulties due to misaligned vertices.


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