# 3D Stars #1: Program for Calculating Dimensions and Angles for 3D Stars

 Blog entry by Aggie69 posted 12-11-2012 09:14 AM 8241 reads 17 times favorited 10 comments
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Have you ever seen a 3 Dimensional star that you really thought was pretty – perhaps on the side of a barn, in someone’s house, or even a Christmas decoration? As a woodworker you may have thought “I’d like to try making one like that.” When you research 3 dimensional (3D) stars on this forum or on the internet as a whole, you’ll be disappointed in what you find. If you’re lucky, you may find a project or two that talks about a specific sized star with fixed dimensions and if you’re really lucky a specific type of tool to make it with! Most of us could easily make a 3D star with the tools we already have in our workshop and could design and make jigs or sleds for easing the job. The BIG PROBLEM - how do we figure out the compound angles necessary???

I got frustrated when I couldn’t find anything on the internet to help me calculate the dimensions and angles necessary to build the shape and size star that I WANTED TO MAKE. High school trig and geometry are 40+ years ago, but with a little refresher reading and some old fashion “keep beating on it til it works”, I developed some equations for calculating the information that I needed. Working with Excel spreadsheets is a lot newer than high school, so I combined my experience with that and the equations to automate calculating dimensions and angles for 3D stars. I developed the equations for a 5-point star and coded them in Excel. I decided that it would be easy to generalize the equations from a 5-point star to an any point star, so I revised my Excel spreadsheet to do just that. It will handle 3 to 8 pointed stars. I also wanted a way to visualize what a star would look like as dimensions changed, so I added a star plotting feature as well. The program is VERY simple. It requires only three user specified variables – the length of one star point, the length from the center of the star to the intersection of two adjacent star points, and the height of the center of the star above the plane the star sits on.

Like most good woodworkers, I enjoy sharing what I’ve done with other woodworkers – for FREE. Below is a link to my Excel spreadsheet. Note that you’ll have to have access to Microsoft Office – Excel to use the spreadsheet. Also, to view the star plot you’ll have to allow your copy of Excel to use Active-X controls (turned off by default because of security issues). Otherwise, everything else will work except the plotting.

3-D Star Calculator.xls

You can also view or download an Adobe PDF file of what the program looks like here –
3-D Star Calculator.pdf

I hope you enjoy the program. I would appreciate feedback about the program and would like to see some STAR Projects.