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65K views 30 replies 19 participants last post by  Aggie69 
#1 ·
Program for Calculating Dimensions and Angles for 3D Stars

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.

You can download a copy of the program here -
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.
 
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#3 ·
Thank you for creating the spreadsheet. I just started to figure out how to make a star then low and behold I found your post. It is very helpful and appreciated. Would it be posible to print the star as a layout at least a small one that would fill up a sheet of paper? Thanks.
 
#4 ·
Being able to print a scaled image to paper would probably need to be done outside of Excel. The programming is more complicated and time consuming than I want to tackle. Using the spreadsheet itself, you can print the picture of the star that the spreadsheet generates to a single sheet of paper along with the various dimensions and angles. That's what I do and then I have one piece of paper in the shop with everything on it that I need to make a star.
 
#10 ·
I just downloaded the program from the same link that is posted and it opened just fine. The file is not encrypted, only the behind the scenes visual basic program is password protected since no one really needs to be messing with it. Try downloading it again. Send me an email, rather than a post, if you continue to have problems. To send me an email, click on "Home" next to my profile picture and select "Send Email".
 
#12 ·
it keeps halting i the process of opening to give me an error that it's protected by a password and can't open. how do I get around this? I'm so frustrated with trying to find the right way to calculate the necessary dimensions for this project and i get the feeling your program is going to be my saving grace if it would only open. lol
 
#13 ·
I just re-downloaded the program from the link above and it ran just fine for me using Windows 10 and Excel 2007. Because it contains Active X commands, you'll get a Security Warning asking if you want to allow them to run (which you do). The program does not need a password to open or run. The Input and Calculations tab allows you to enter data into any of the 4 User Input cells. All of the other cells that do the calculations behind the scenes ARE PASSWORD PROTECTED because the user doesn't need to mess with them. The program should open and work just fine - if it doesn't, then it's probably an internal security setting in the version of Excel that you have and I can't help you with that.
 
#15 ·
Compound Angle Cutting Jig with Hold Downs for a Radial Arm Saw

Trying to cut narrow pieces for the stars at steep angles and bevels on my radial arm saw required some assistance.

I designed a simple jig that would clamp into the table in the fence joint, anywhere along the fence joint. You can make angle cuts to ~60 degrees left or right while leaving the saw carriage arm to run straight back and forth. You can bevel the saw carriage to ~70 degrees to create compound cuts on small pieces. Best of all, you can clamp down the workpiece and keep your hands clear of the blade while your're cutting!

Wood Circuit component Beige Electrical wiring Electrical supply


Sleeve Beige Collar Wood Jewellery


I used a mini-T track fastened into the wood angle arm and 1/4" x 20 hex head bolts and knobs for the hold down hardware (purchased from Peachtree Woodworking Supply). The clamps were homemade from 1" x 1/4" x 4", 5", or 6 "ash with 1/4" wide slots in the center. The ends of the hold downs were soft pine to reduce surface dinging of the held down workpiece. The pivot point bolt and the circle hold down bolt are 1/4" x 20 "elevator" bolts (flat head, ~1" dia). The jig table is MDF, the wood angle arm is ash, and the fence is pine.

My normal 10" saw blade wouldn't clear the top of the jig on bevels from about 20 degrees to 70 degrees. Changing out the blade to a 7-1/4" blade worked great. Not wanting to cut up my jig everytime I make a cut, I use a piece of sacrificial 1/8" hardboard (Masonite) underneath the piece being cut. In the picture below, the saw guard has been removed and the saw carriage raised for picture clarity

Wood Floor Flooring Hardwood Wood stain
 

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#16 ·
Compound Angle Cutting Jig with Hold Downs for a Radial Arm Saw

Trying to cut narrow pieces for the stars at steep angles and bevels on my radial arm saw required some assistance.

I designed a simple jig that would clamp into the table in the fence joint, anywhere along the fence joint. You can make angle cuts to ~60 degrees left or right while leaving the saw carriage arm to run straight back and forth. You can bevel the saw carriage to ~70 degrees to create compound cuts on small pieces. Best of all, you can clamp down the workpiece and keep your hands clear of the blade while your're cutting!

Wood Circuit component Beige Electrical wiring Electrical supply


Sleeve Beige Collar Wood Jewellery


I used a mini-T track fastened into the wood angle arm and 1/4" x 20 hex head bolts and knobs for the hold down hardware (purchased from Peachtree Woodworking Supply). The clamps were homemade from 1" x 1/4" x 4", 5", or 6 "ash with 1/4" wide slots in the center. The ends of the hold downs were soft pine to reduce surface dinging of the held down workpiece. The pivot point bolt and the circle hold down bolt are 1/4" x 20 "elevator" bolts (flat head, ~1" dia). The jig table is MDF, the wood angle arm is ash, and the fence is pine.

My normal 10" saw blade wouldn't clear the top of the jig on bevels from about 20 degrees to 70 degrees. Changing out the blade to a 7-1/4" blade worked great. Not wanting to cut up my jig everytime I make a cut, I use a piece of sacrificial 1/8" hardboard (Masonite) underneath the piece being cut. In the picture below, the saw guard has been removed and the saw carriage raised for picture clarity

Wood Floor Flooring Hardwood Wood stain
nice jig
 

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#20 ·
Making 3-D Stars

After creating a program to calculate dimensions and cutting angles and designing and building a jig to make the cuts with, I was ready to put things into practice.

My first trial was with some old (30+years) cedar fence pickets. I wanted an old "barnwood" 3-D star. I quickly decided that even though the wood was cheap (free), it varied greatly in thickness, even within one piece, and it was extremely brittle and splintered easily when cut. Needless to say, I wasn't pleased with the finished pieces.

My next attempt was with new 1Ă—4 rough cedar that I already had on hand (slightly thinner cedar fence pickets would work equally well). This material worked much better. I made several different cuts and kept changing my cutting jig around trying to get the pieces like I wanted. After a lot of trial and error I finally came up with a set of simple and easy cuts to simplify the process that I'll cover in a moment.

First, however, I made the pieces for a 3-D star that had a "Long Arm" = 9 inches, a "Short Arm" = 3.44 inches, and a center "Height" = 1.5 inches. I cut the bevels for all 3 sides just like my program calls for and the resulting star layed flat on the table.

Triangle Creative arts Art Wood Wheel


While the star is very pretty, it's also very thin on the outside edges and at the star points which makes it very fragile. Additionally, trying to cut the very steep undercut bevel on the outside edge (61.7 degrees in this case) removes a lot of material and must be done in at least 2 passes to keep the edge smooth and on angle.

I decided to try a little different approach to see how I liked it and was quite pleased with the outcome. I decided to NOT bevel the outside edge, but to leave it uncut. Since it is at a 90 degree angle with the top surface, when the piece is elevated to its 3-D position, this edge naturally angles back under the star. Now the star is much thicker, sturdier, and much easier to make.

This picture is of both stars, with the thicker star on the left.

Triangle Star Wood Symmetry Circle


This is the same setup but at an angle to highlight the difference in the stars.

Wood Creative arts Triangle Pattern Art


Here's a closeup of the outside edges.

Table Rectangle Wood Beige Triangle


The following picture shows the progression of cuts needed to make the second star.

Triangle Wood Rectangle Font Wood stain


On a Radial Arm Saw (RAS) make the star as follows:

1. Cut a length of stock that is wide enough to make one piece and 1/2" to 1" longer than the "Long Arm" length. Cut a set (5 point star = 5 pieces, but cut at least 1 or 2 extra for spares).

2. With the GOOD SIDE UP, cut the "Long Arm" bevel on the outside edge of the work piece. Rotate it 180 degrees and cut the same bevel on the other outside edge. Repeat for all pieces.

3. Set the jig in the 5 o'clock position with the angle between the saw blade and the jig hold down at the "Point Angle". Put the saw blade straight up and down.

3a. - Put a piece in the jig with the GOOD SIDE UP. Slide it up and down the jig hold down until the saw blade will contact the outside edge about 1/4" down from the upper edge of the work piece. Clamp it and cut. When the piece is cut, it will yield 2 RIGHT HALF star point blanks. Do this for half of the work piece blanks that you have.

3b. Put a piece in the jig with the GOOD SIDE DOWN. Slide it up and down the jig hold down until the saw blade will contact the BOTTOM outside edge about 1/4" down from the upper edge of the work piece. Clamp it and cut. When the piece is cut, it will yield 2 LEFT HALF star point blanks. Do this for the other half of the work piece blanks that you have.

4a. Adjust the jig to the 7 o'clock position with the angle between the saw blade and the jig hold down at the "Interior Angle". Adjust the saw blade to the "Short Arm Bevel Angle". Using a RIGHT HALF star point blank, place it GOOD SIDE DOWN with the "Long Arm" edge against the guide. Slide it up and down the jig hold down until the blade will cut the "Long Arm" the correct "Long Arm" length. Clamp it and cut. Repeat this for all of the RIGHT HALF blanks.

4. Adjust the jig to the 5 o'clock position with the angle between the saw blade and the jig hold down at the "Interior Angle". Adjust the saw blade to the "Short Arm Bevel Angle". Using a LEFT HALF star point blank, place it GOOD SIDE DOWN with the "Long Arm" edge against the guide. Slide it up and down the jig hold down until the blade will cut the "Long Arm" the correct "Long Arm" length. Clamp it and cut. Repeat this for all of the LEFT HALF blanks.

5. Double check all of the pieces for consistency from piece to piece and make any corrections needed before proceeding.

6. Glue up enough right and left half sets for a finished star. Allow them to dry before proceeding.

7. Dry fit the pieces together and make sure that all of the gaps between the segments will close up properly. They probably won't, so now is the time to hand/power sand some of the edges so everything will fit together. Glue up and enjoy!!!
 

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#21 ·
Making 3-D Stars

After creating a program to calculate dimensions and cutting angles and designing and building a jig to make the cuts with, I was ready to put things into practice.

My first trial was with some old (30+years) cedar fence pickets. I wanted an old "barnwood" 3-D star. I quickly decided that even though the wood was cheap (free), it varied greatly in thickness, even within one piece, and it was extremely brittle and splintered easily when cut. Needless to say, I wasn't pleased with the finished pieces.

My next attempt was with new 1Ă—4 rough cedar that I already had on hand (slightly thinner cedar fence pickets would work equally well). This material worked much better. I made several different cuts and kept changing my cutting jig around trying to get the pieces like I wanted. After a lot of trial and error I finally came up with a set of simple and easy cuts to simplify the process that I'll cover in a moment.

First, however, I made the pieces for a 3-D star that had a "Long Arm" = 9 inches, a "Short Arm" = 3.44 inches, and a center "Height" = 1.5 inches. I cut the bevels for all 3 sides just like my program calls for and the resulting star layed flat on the table.

Triangle Creative arts Art Wood Wheel


While the star is very pretty, it's also very thin on the outside edges and at the star points which makes it very fragile. Additionally, trying to cut the very steep undercut bevel on the outside edge (61.7 degrees in this case) removes a lot of material and must be done in at least 2 passes to keep the edge smooth and on angle.

I decided to try a little different approach to see how I liked it and was quite pleased with the outcome. I decided to NOT bevel the outside edge, but to leave it uncut. Since it is at a 90 degree angle with the top surface, when the piece is elevated to its 3-D position, this edge naturally angles back under the star. Now the star is much thicker, sturdier, and much easier to make.

This picture is of both stars, with the thicker star on the left.

Triangle Star Wood Symmetry Circle


This is the same setup but at an angle to highlight the difference in the stars.

Wood Creative arts Triangle Pattern Art


Here's a closeup of the outside edges.

Table Rectangle Wood Beige Triangle


The following picture shows the progression of cuts needed to make the second star.

Triangle Wood Rectangle Font Wood stain


On a Radial Arm Saw (RAS) make the star as follows:

1. Cut a length of stock that is wide enough to make one piece and 1/2" to 1" longer than the "Long Arm" length. Cut a set (5 point star = 5 pieces, but cut at least 1 or 2 extra for spares).

2. With the GOOD SIDE UP, cut the "Long Arm" bevel on the outside edge of the work piece. Rotate it 180 degrees and cut the same bevel on the other outside edge. Repeat for all pieces.

3. Set the jig in the 5 o'clock position with the angle between the saw blade and the jig hold down at the "Point Angle". Put the saw blade straight up and down.

3a. - Put a piece in the jig with the GOOD SIDE UP. Slide it up and down the jig hold down until the saw blade will contact the outside edge about 1/4" down from the upper edge of the work piece. Clamp it and cut. When the piece is cut, it will yield 2 RIGHT HALF star point blanks. Do this for half of the work piece blanks that you have.

3b. Put a piece in the jig with the GOOD SIDE DOWN. Slide it up and down the jig hold down until the saw blade will contact the BOTTOM outside edge about 1/4" down from the upper edge of the work piece. Clamp it and cut. When the piece is cut, it will yield 2 LEFT HALF star point blanks. Do this for the other half of the work piece blanks that you have.

4a. Adjust the jig to the 7 o'clock position with the angle between the saw blade and the jig hold down at the "Interior Angle". Adjust the saw blade to the "Short Arm Bevel Angle". Using a RIGHT HALF star point blank, place it GOOD SIDE DOWN with the "Long Arm" edge against the guide. Slide it up and down the jig hold down until the blade will cut the "Long Arm" the correct "Long Arm" length. Clamp it and cut. Repeat this for all of the RIGHT HALF blanks.

4. Adjust the jig to the 5 o'clock position with the angle between the saw blade and the jig hold down at the "Interior Angle". Adjust the saw blade to the "Short Arm Bevel Angle". Using a LEFT HALF star point blank, place it GOOD SIDE DOWN with the "Long Arm" edge against the guide. Slide it up and down the jig hold down until the blade will cut the "Long Arm" the correct "Long Arm" length. Clamp it and cut. Repeat this for all of the LEFT HALF blanks.

5. Double check all of the pieces for consistency from piece to piece and make any corrections needed before proceeding.

6. Glue up enough right and left half sets for a finished star. Allow them to dry before proceeding.

7. Dry fit the pieces together and make sure that all of the gaps between the segments will close up properly. They probably won't, so now is the time to hand/power sand some of the edges so everything will fit together. Glue up and enjoy!!!
As it is late & I need to be up veeeeery early, I don't have the time or mental capacity to thoroughly comprehend everything involved.
However, I wanted to say; Thank You, for doing this blog.
 

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