Introduction: How to Quickly Create a Lighted Christmas Star

Every city has a few houses that go overboard with giant lighted lawn decorations during the Christmas holiday.  The thought of hand drilling zillions of holes for stuffing with tiny lights has kept me from even putting up a few small decorations.

This year, I'm changing that…as a member of TechShop, I have access to a cool CNC router (love that ShopBot!).  So, I'm going to make it do the tedious work of drilling all those holes and cutting out the decoration's shape.

This instructable walks through the design/drawing of a "Star of Bethlehem". It also shows how to reduce laying out more than a hundred holes for lights to a matter of a couple simple steps.  

I used VCarve Pro to layout the entire project and to create the toolpaths for the ShopBot.

Most steps will have at least three photos to help explain what needs to be done.  The first photo shows where on VCarve's screen to find the tool.  The second photo shows the settings used by that tool.  The third photo shows what the drawing should look like after using the drawing tool so you can verify what each tool is supposed to do.

I made this at TechShop San Jose and plan to use this project for the November 2012 ShopBot Meetup.  For more info on TechShop, visit their website at http://techshop.ws

Step 1: Materials & Tools

Materials
  • Half sheet of 1/2” exterior grade plywood
  • Half sheet of backer material (because we’re going to drill through our plywood and don’t want to tear up the ‘Bot’s surface)
  • Exterior paint
  • Sandpaper (a sheet or two of 180 or 220 grit)
  • Christmas lights (buy these before you go any further so you know how many holes to drill)
  • I used two strands of Philips twinkling cool white LED indoor/outdoor lights, 60 lights/strand, 120 lights total (make sure your lights are rated for exterior use!)


Tools
  • 1/4” end mill bit (preferably rated for plunging…mine were purchased from http://centuriontools.com)
  • ShopBot big enough to handle a half sheet of plywood
  • VCarve Pro software (available on TechShop’s hub machines)
  • Palm or orbital sander
  • Laminate trimmer with a flush cutting bit.

Step 2: Create a New Drawing

In order to make the ShopBot do the dirty work of drilling all those holes, a bit of vector drawing work needs to be done.  The vectors in our drawing will be converted into the toolpaths that tell the ShopBot where to drill the holes and how to cut out the star’s shape.

If the drawing steps aren’t quite clear, study the partial screen shots that go with each step.  They should show all the settings and details required along the way.  It’s important to not skip steps, not wander off on your own, and to verify each step was successful before moving to the next part.

Please leave questions in the Comments section below if there’s anything that’s confusing, unclear, broken, etc.  Instructables are fairly easy to correct. If it’s confusing you, it’ll confuse somebody else, so please let me know and I’ll try to clear it up.

I used VCarve Pro v6.503 to draw my Star.

Create a new file (see the first image in this step to see the settings listed below):
  • Set the width and height both to 48”.
  • Set the thickness to 0.5” (adjust if you’re using thicker plywood).
  • Set the “Z Zero” to the bottom.
  • Set the “XY Origin Position” to the bottom, left corner.
  • Turn off “Origin Offset”.
  • Turn off “Data Scaling”.
  • Click the “OK” button.

Step 3: Start With a Simple 8-Point Star

Start by selecting the “Draw Star” tool (see image 1 in this step for the location of this tool). I placed the star high enough to allow later stretching its bottom leg significantly downwards without falling out of the drawing space.


Set the “Draw Star” tool’s fields (see image 2 for where each field can be found):
  • Set the “Number of Points” = 8
  • Set the “Center Point” to:
    •  X = 13
    •  Y = 34
  • Set the “Outer Radius” = 12
  • Set the “Inner Radius Percentage” = 50
  • Click the “Create” button.
  • Click the “Close” button.


Your drawing should currently look like image 3 of this step.

Step 4: Add Guides to Simplify Adjusting the Star's Points

Notice that all the points of this star are the same length.  The goal is to have the four legs that are 45 degrees off of vertical to be slightly shorter and the bottom leg to be much longer.  Placing two basic shapes precisely on the drawing will simplify changing the lengths of the star’s legs.

Start by selecting the “Draw Rectangle" tool - please don’t close it until instructed to (image 1 of this step shows where that tool is located, image 2 shows where to fill in the values listed below):
  • Set the “Anchor Point” to the upper left corner to:
    •      X = 1
    •      Y= 34
  • Set “Corner Type” to “Square”.
  • Set “Size” to:
    •      Width (X) = 12
    •      Height (Y) = 24
  • Click the “Create” button.

NOTE: Leave the Draw Rectangle tool open.

Image 3 of this step shows the results of adding that rectangle to the drawing.


Draw a second (and smaller) rectangle while the Draw Rectangle tool is open.  Image 4 shows the settings described below:

• Change the “Anchor Point” to the center.

NOTE: Be certain you change the anchor point or the square will be in the wrong location for the next steps.
  • Set the “X” and “Y” for the “Anchor Point” to:
    • X = 13
    • Y = 34
  • The “Corner Type” should remain “Square”.
  • Change the “Size” to:
    • Width (X) = 14
    • Height (Y) = 14
  • Click the “Create” button.
  • Click the “Close” button (the Draw Rectangle tool is no longer needed).

Image 5 shows the expected results from adding the second rectangle.

Step 5: Use the Guides to Adjust the Points

A few moves with the Node-Editing tool will shrink four legs and stretch the bottom leg.  

Start by selecting the “Node Editing” tool (image 1 in this step shows the tool's location).
  • Click on the star in your drawing to select it (see image 2 which shows the nodes on the star after it was selected).
  • Drag the first star point inward to the closest corner of the square to shorten that star leg (see image 3, the new location is shown in blue during the drag). The square that was drawn earlier as a guide gives a convenient “snapping” point for the cursor so the resizing is quick & easy.
  • Drag the other three points inward that need to be shortened (see image 4).
  • Drag the bottom point on the star straight down to the bottom-right corner of the large rectangle (see image 5 which shows the bottom leg's new position in blue as it's being dragged downwards).
  • Click on the “Selection Mode” tool (see image 6 to see the tool's location).
  • Use the “Selection Mode” tool to select & delete both the rectangle and the square that were used to guide resizing the star's legs.

Your drawing should currently look like image 6.

NOTE: Now is a good time to save your drawing.

Step 6: Make Two Paths for Quick Hole Layout

The “Copy object along vectors” tool will speed up laying out most of the holes for the lights,. To use that tool, two smaller copies of the star’s outline will be created, scaled down, and used as inputs to that tool. This will leave an area near the center hole-free. That hole-free area will be filled in by a later step.


First, create one of the two vectors that will be used to copy holes along:
  • Select the outline of the star.
  • Press CTRL-C to copy it to the clipboard.
  • Press CTRL-V to paste a copy into the drawing.


Select the “Set Selected Objects Size” tool (see image 1 for the location of this tool and image 2 for where to enter the settings spelled out below).
  • Set the “Anchor” point to the center.
  • Verify that “Link XY” is checked.
  • Set Width (X) = 18 (VCarve will set “Height (Y)” since “Link XY” is checked.)
  • Click the “Apply” button.
  • Click the “Close” button.

Your drawing should now look like image 3.


Verify the new, smaller star outline is selected.

Pick the “Move Selected Objects” tool (see image 4 for this tool's location and image 5 for its settings).
  • Set “Type of Move” to “Relative”.
  • Leave X = 0
  • Set Y = 1.5
  • Click the "Apply" button.
  • Click the "Close" button.

The smaller star should now be centered within the original star and should look like image 6.


We need one more, even smaller, copy of the star's original outline before we can layout the holes for lights. Just repeat the steps above using smaller values for the resizing tool and a slightly larger value for the move tool:
  • Select the outline of the star.
  • Press CTRL-C to copy it to the clipboard.
  • Press CTRL-V to paste a copy into the drawing.

Select the “Set Selected Objects Size” tool (see image 1 for the location of this tool and image 7 for the settings).
  • Set the “Anchor” point to the center.
  • Verify that “Link XY” is checked.
  • Set Width (X) = 12
  • Click the “Apply” button.
  • Click the “Close” button.
Your drawing should now look like image 8.


Verify the new, smaller star outline is selected.

Pick the “Move Selected Objects” tool (see image 4 for this tool's location and image 9 for this tool's settings).
  • Set “Type of Move” to “Relative”
  • Leave X = 0
  • Set Y = 3
  • Click the “Apply” button.
The smallest star should now be properly centered within the original star and should look like image 10.
  • Click the “Close” button.

Step 7: Time to Lay Out Some Holes!

With the two smaller star paths in place, VCarve is ready to quickly create most of the holes for the lights: 

Select the “Copy Objects Along Vector” tool (see image 1 for this tool's location).
  • Select only the two smaller star paths created earlier.
  • Click “Copy Circles” within the “Copy Along Vectors” tool settings window (image 2).
  • Set “Diameter” = 0.47” (If you use different lights, you may need a different sized hole.)
  • Select "Distance between copies" (instead of "Number of copies").
  • Set “Distance between copies” = 1.4”
  • Verify “Align vectors to curve” is unchecked.
  • Verify “Create copies on a new layer” is unchecked.
  • Click the “Copy” button.
  • Click the “Close” button.

Your drawing should now look like image 3.


The two small copies of the star's outline are no longer needed.  To remove them, pick the “Selection Mode” tool, then select and delete ONLY the two smaller star paths that were used to guide placing the light holes.


NOTE: The overlapping holes will be fixed in a later step.

Your drawing should currently look like image 4.

Changing the value for “Distance between copies” will move the holes closer together (smaller values) or further apart (larger values). If the holes are closer together, more holes will be placed along the paths fed into the “Copy Objects Along Vector” tool. Fewer holes will be created if the holes are spaced further apart.

When creating your own designs, don't forget to adjust that spacing value to quickly produce more (or fewer) holes.

Step 8: Fill in the Gap (Part 1)

There should be 107 light-holes in the drawing at this time.  To verify that number, press CTRL-A to select everything in the drawing. 

In the bottom, right hand corner of VCarve’s window, when one or more items have been selected, three fields of text appear that show the selection’s width (“W:”), height (“H:”), and how many items are selected (“S:”). For the drawing’s current state, it should show “S:108” which includes the 107 holes plus the outline of the star.

Image 1 shows what this should look like along the bottom right corner of VCarve's drawing window.

I used two strands with 60 lights/strand so I need 120 holes for lights.  Since there are currently only 107 holes for light, the drawing needs another 13 holes. Those holes will be used to fill the gap in the center. Part of the gap will be filled in by this step and the rest will be filled in by the next step. Both this step and the next step use the same VCarve tool, but with slightly different settings.

One of VCarve's fancier tools will be used to fill that gap.

That tool requires one spare light-hole to be created at a known location. First, create the spare hole, then feed that hole to the "Copy objects in a linear or circular array” tool.

Pick the “Draw Circle” tool (see image 2 for this tool's location and image 3 for its settings).
  • Set the “Center Point” to:
    • X = 6
    • Y = 24
  • Select “Diameter”
  • Set “Diameter” to:
    • D = 0.47”
  • Click the “Create” button.
  • Click the “Close” button.

Select the hole that was just created in the drawing.

Pick the “Copy objects in a linear or circular array” tool (see image 4 for this tool's location and image 5 for its settings).
  • Select “Circular Array” (about half way down the tool's settings window).
    • Set its “Rotation Center” to:
      • X = 4.5
      • Y = 22.5
      • Set “Number of items” = 8
  • Select “Total Angle"
    • Set “Total Angle” = 360
  • Click the “Copy” Button.
  • Click the “Close” Button.

To move the newly created ring of 8 holes into the center of the star, verify the new holes are selected, then:

Pick "Move Selected Objects" tool (image 7 shows the location of this tool and image 8 shows its settings).
  • Set the “Anchor” point to center.
  • Set "Type of Move" to Absolute.
  • Set "X Position" to 13
  • Set "Y Position" to 34
  • Click the “Apply” button.
  • Click the “Close” button.

Your drawing should now look like image 9. The small gap at the very center will be filled in by the next step.

Step 9: Fill in the Gap (Part 2)

Selecting everything in the drawing should show that there are now 115 holes (the selection counter will show 116 because the star’s outline is also selected). 

That means, five more holes need to be created which should nicely fill the little bit of gap that still exists at the star's center. Just like the prior step, a spare light hole needs to be created, then fed to the “Copy objects in a linear or circular array” tool.

Pick the “Draw Circle” tool (image 1 shows the tool's location and image 2 shows its settings).
  • Set the “Center Point” to:
    • X = 6
    • Y = 24
  • Select “Diameter”
  • Set “Diameter” to:
    • D = 0.47”
  • Click the “Create” button.
  • Click the “Close” button.

Select the hole that was just created in the drawing.

Pick the “Copy objects in a linear or circular array” tool (see image 3 for this tool's location and image 4 for its settings).
  • Select “Circular Array” (about half way down the tool's settings window).
  •   Set its “Rotation Center” to:
    •   X = 5.5
    •   Y = 23.5
    •   Set “Number of items” = 5
  • Select “Total Angle"
  • Set “Total Angle” = 360
  • Click the “Copy” Button.
  • Click the “Close” Button.

To move the newly created ring of 5 holes into the center of the star, verify the new holes are selected, then pick "Move Selected Objects" tool (image 5 shows the location of this tool and image 6 shows its settings).
  • Set the “Anchor” point to center.
  • Set "Type of Move" to Absolute.
  • Set "X Position" to 13
  • Set "Y Position" to 34
  • Click the “Apply” button.
  • Click the “Close” button.
Your drawing should look like image 7.  Now would be a good time to save your progress again.

Step 10: Fine Tune Hole Locations

There are a few holes overlapping other holes.  To fix that, simply drag each overlapping hole somewhere else in the drawing (within the outline of the star). For example, drag one down to the empty space near the bottom of the longest leg.

Try to keep at least a quarter of an inch between the edges of the star's outline and the closest edge of each hole.  Otherwise, the outer edge of the star may be easily broken after the holes are drilled.

Move any holes that appear too close to another hole to somewhere that looks like it could use a hole of its own. Try to leave at least a half inch of solid material between holes (and separate any holes that don’t follow that suggestion).

Step 11: Create a Toolpath to Drill the Holes

I prefer to create two tool paths for projects like this one.  The first path will cut all of the holes for lights and is described in this step. The second path will cut the star's outline and will be described in the next step.

The fit of your lights should be tested on a few sample holes drilled into scraps. If you use different lights, make sure to test-fit your holes before cutting the star’s outline!

VCarve has a drilling function built in but I'm intentionally avoiding that tool.  It would let me easily drill the holes using a traditional drill bit, but then I'd have to change to an end mill in order to cut the star's outline. Changing bits means resetting the Z-axis' zero point which eats time (needlessly in this case).

When drilling holes larger than my end mill, I find it quick & easy to just let the end mill make the holes. A drill bit likely makes more precise diameter holes, but for this project, precision isn't critical enough to warrant shuffling bits back and forth.

To create the tool path for the 120 light-holes, the "Toolpaths" panel will need to be open. That panel lurks along the upper right corner of the drawing behind a tab labeled, "Toolspaths".  See image 1 for the location of this panel's tab when that panel is closed.

If the Toolpaths panel is not already open, click on the “Toolpaths” tab.  Then, click on the sideways pushpin icon in the panel's upper right corner to keep that panel from automatically closing.
  • Press CTRL-A to select everything in your drawing.
  • SHIFT-click on the star’s outline to deselect it (leaving ONLY the 120 light holes selected).

NOTE: My end mills are rated for plunging - if yours are NOT, you may need a longer ramp. I could skip the ramp completely but prefer keeping it in when sharing project settings in case somebody uses my settings with a bit that is NOT rated for plunging.


In the Toolpaths panel, click on the “Create Profile Toolpath” operation (image 2 shows this tool's location within the Toolpaths panel and Image 3 shows the settings used):
  • Set "Start Depth (D)" to 0.
  • Set “Cut Depth (C)” to 0.02 DEEPER than your material's thickness (0.52" since I'm using half inch thick material). This ensures the bit will cut cleanly all the way through if the table is slightly uneven. This REQUIRES using your own backing board because the bit WILL cut into the backing board.    
  • Pick the bit you'll be using, set its RPMs, and set its feed rate (I'm using a .25" end mill, 15K RPM, 4 inches/sec).
  • Set “Passes” = 2 (if you use thicker material, increase the number of passes).
  • Set "Machine Vectors…" to Inside/Left.
  • Set “Direction” to “Climb”.
  • No tabs!
  • Click on the “Ramps” tab:
    • Check the "Add ramps to toolpath" box.
    • Click the “Smooth” button.
    • Set “Distance” to 0.5”.
  • Name this tool path:
    • I used, “Holes .25in end mill, 4in sec, 15K rpm”.
  • Click the “Calculate" button.
NOTE: A warning dialog should pop up advising you're going to cut thru the material.  This is intentional and it’s why I noted earlier that you’ll need to have your own backing board under the piece you’re cutting into your star.
  • Click the “OK” button to dismiss the warning dialog.

After VCarve calculates the toolpath, it should switch the main drawing area to show a “3D View” similar to image 4.

Many problems that will show up during cutting can be spotted by using VCarve's "Preview" capability. I highly recommend always previewing, and studying closely, all new toolpaths.

To see the results of "cutting" this toolpath, click the “Preview Toolpath” button in the Toolpaths panel (image 5 shows that button highlighted in blue).

Image 6 shows what the preview should look like after "drilling" the 120 holes for lights.

After studying the preview of the hole-drilling toolpath, click the “Close” button at the bottom of the Preview panel.

Switch the main window back to the drawing area before going to the next step.  To do that, click on the tab along the upper left edge of the drawing area to see the drawing instead of the toolpath preview.

NOTE:  The tab will have the name of your file showing. For the screen shots in this Instructable, my file name was “walkthru 1”.

Step 12: Create a Toolpath to Cut the Star's Outline

To create the toolpath for cutting the star’s outline, click on only the outline of the star in the drawing area.

Click on “Create Profile Toolpath” in the Toolpaths panel (image 1 shows its location and image 2 shows its settings).
  • Set "Start Depth (D)" to 0.
  • Set “Cut Depth (C)” to 0.02 DEEPER than your material's thickness (0.52" since I'm using half inch thick material). This ensures the bit will cut cleanly all the way through if the table is slightly uneven. This REQUIRES using your own backing board because the bit WILL cut into the backing board.
  • Pick the bit you'll be using, set its RPMs, and set its feed rate (I'm using a .25" end mill, 15K RPM, 4 inches/sec).
  • Set “Passes” = 2 (if you use thicker material, increase the number of passes).
  • Set "Machine Vectors…" to Outside/Right. (this is different from the prior step)
  • Set “Direction” to “Climb”.
NOTE: This toolpath requires tabs! Cutting is faster using 3D tabs, but I find the default size for those a bit fragile. I like my 3D tabs a little beefier. To increase the size of the 3D tabs:
  • Under “Tabs”, check the “Adds tabs to Toolpath” box.
  • Set “Length” = 0.75”
  • Set “Thickness” = 0.2”
  • Click the “Create 3D tabs” box.
  • Click the "Edit Tabs" button:
    • Manually place two tabs along the long lower leg (one on each side).
    • Manually place a tab along the top edge of each horizontal leg.
    • That’s a total of 4 tabs.
    • Click on the "Close" button to get back to the 2D Profile Toolpath panel.
  • Click on the “Ramps” tab:
    • Check the "Add ramps to toolpath" box.
    • Click the “Smooth” button.
    • Set “Distance” to 0.5 inches
NOTE: My end mills are rated for plunging - if yours are NOT, you may need a longer ramp. I could skip the ramp completely but prefer keeping it in when sharing project settings in case somebody uses my settings with a bit that is NOT rated for plunging.


• Name this tool path.  I used, “Star .25in end mill, 4in sec, 15K rpm”.

• Click the “Calculate" button.

NOTE: A warning dialog should pop up advising you're going to cut thru the material.  This is intentional and it’s why I noted earlier that you’ll need to have your own backing board under the piece you’re cutting into your star.

* Click the “OK” button to dismiss the warning dialog.
After VCarve calculates the toolpath, it should switch the main drawing area to show a “3D View” similar to image 3.

Many problems that will show up during cutting can be spotted by using VCarve's "Preview" capability. I highly recommend always previewing, and studying closely, all new toolpaths.

To see the results of "cutting" this toolpath, click the “Preview Toolpath” button in the Toolpaths panel (image 4 shows that button highlighted in blue).

Image 5 shows what the preview should look like after "cutting" the outline of the star. If you look closely, the four tabs I described earlier are visible along the star's outline.

When you're done studying the preview, click on the "Close" button at the bottom of the "Toolpaths" panel.  It's OK to leave the Preview showing in the main part of VCarve's screen.

Step 13: Save the Toolpaths

In order to get the ShopBot to actually cut the toolpaths I just generated, VCarve needs to be told to export them.

In the Toolpaths panel’s “Toolpath List”, select the “Holes” toolpath (see image 1).

In that same panel, click on the “Save Toolpath” tool (shown along the bottom of image 1). This changes the contents of the Toolpaths panel to look like image 2.
  • Verify that the toolpath for making your holes is the only thing selected in the Toolpath List.
  • Uncheck the “Output all visible toolpaths to one file” box (this will allow VCarve to create a file that only cuts the holes for lights).
  • Select the proper “Post Processor” from the popup menu. For TechShop San Jose, I use “ShopBot Arc (inch) w/speed(*.sbp)”.
  • Click the “Save Toolpath(s)” button.
    • The default file name VCarve suggest will be the same as the toolpath’s name.
    • Add a version number at the end of the name if you want to experiment with different settings, bits, speeds…
  • Save the toolpath to disk by clicking on the "Save" button.

NOTE: Do not close this panel yet.

Click on the other toolpath you created (the one that cuts the outline of the star).
  • Verify the "Post Process" is still correct for your target machine.
  • Click the “Save Toolpath(s)” button.
  • Click on the "Save" button to save the toolpath to disk.
  • Click the “Close” button at the bottom of the “Toolpaths List” panel.

Step 14: Put Your Toolpaths on a Thumb Drive & Get Ready to Cut

In order to use the new toolpaths on a ShopBot, we need to get them onto the computer attached to the ShopBot.  Drag the tool path files onto a thumb drive, use sneakernet to get your thumb drive over to the ShopBot's computer, then copy your files from the thumb drive onto the ShopBot's computer.

Place your backer board onto the ShopBot's table and place your exterior grade plywood on top of your backer board.

Secure your plywood and backer board to the table.

I won't go into full details on how to use the toolpaths on the ShopBot.  TechShop requires members to pass a safety & basic use class before they can use a ShopBot.  So, anybody trying to do this project should already know how to load and cut these toolpaths.

Image 1 shows my plywood on the ShopBot's table just after the 120 holes for lights were cut.

Image 2 shows my plywood on the ShopBot's table just after the outline of the star was cut.

My total cutting time was less than 12 minutes if I recall correctly.

Step 15: Cleanup & Paint

Cut the tabs to release the star from the rest of the plywood sheet.  I use a laminate trimmer with a flush cutting bit to quickly remove the leftover bits of the tabs.

Make a quick pass or two along the edges and faces of the star with a palm (or orbital) sander using 180-220 grit.

I used TechShop's paint booth and a can of spray paint for this project.  The holes in the star gave me plenty of places to suspend the star during painting.  The paint booth quickly took care of the overspray and the fumes.

Let one side dry to the touch before repositioning the star to paint the other side.  I used different holes to hang the star by each time I repositioned it.  That prevented the heavy wire holding the star in place from leaving unpainted shadows.

Step 16: Stuff the Lights

The strands I bought are supposed to twinkle.  When I plugged them in, I discovered that only some of the bulbs twinkle while at least half stay on full time.

Test your lights before you stuff them into the holes, then use your knowledge of which lights twinkle and which ones stay on full time to guide which lights go into which holes.

I found that the wire between lights was easier to manage if I didn't try to put the next bulb in a hole adjacent to where I'd just placed the prior bulb.

Instead, I placed the next bulb about as far away as I could from the prior bulb...bouncing back and forth, side to side, like a peg-jumping game.  Just try not to leave unfilled holes in places you can't hop back to easily.

If you want to secure the wires to the back of your star, there are wiring staplers readily available at Target, Lowes, etc...I found mine in the Christmas decoration aisles at Target.  The staples include a plastic sleeve that prevents the staple from quickly rubbing through the wire's insulation.  

Target listed it as, “Holiday Light Tacker with Staples”. It was about $7 on clearance and its Store Item Number (DPCI) is 051-19-0601.

Step 17: Mounting Your Star

I'll likely attach my star to my fence using a couple of screws through the front, carefully avoiding the wires in the back...

There are plenty of other options, most of which are more elegant than my plan and all of which are beyond the scope of this instructable.

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