Introduction: Laser Cut Table Centerpiece - Crab Candleholder

By Bad Rabby Designs
About: JoeJoe is a PCB designer, artist, and make-hack-tinkerer who lives in San Francisco, CA. He is currently an Artist-in-Residence at the Autodesk Pier 9 Workshop, and also co-founded LumiGeek (www.lumigeek.com)…

The laser cutter is an awesome tool for making quick decorations for parties, weddings, or special outings.  The speed at which it can vector cut thin wood makes it ideal for short production runs in a single hour or two of work.

In this Instructable, we will lay out a crab candleholder and do a few shape-related tricks in CorelDraw to make it stand up and nest properly.

Step 1: Lay Out the Vector Shape in Corel and Set Up the Workspace

The first step is to place and center your shapes on a page.  Here I have set up a 36" x 24" page and placed two identical crabs.  Use the "Align Centers Horizontally" tool under Arrange->Align and Distribute to make sure they are centered.  Then bring in three guides- one on the center of each vertically, and one on the horizontal center.

Step 2: Measure Your Material

To make the centerpiece stand up, you need to create a slot that is only slightly bigger than the width of your material.  If the slot is too big it will be wobbly, and if it is too small they obviously won't fit together.

Note that the kerf and line width of the laser cut will depend on both your machine and your focal point, so this step often requires a little trial and error before you go into production mode.  It took me two test cuts with the crab to get it "just right".  To save material, you can do the next step with a small square of material rather than your large design.

Here we have around .2" thickness for this plywood with a nice veneer finish on both sides.

Step 3: Add the Slots to Your Design and Subtract Them From the Shape

Ok.  Here's the fun part.

Create a rectangle in Corel using the measurement of the material that you just made as the width.  This is going to be the slot to let them stack, and may require a little trail and error as mentioned before as the laser cut width will be a variable.  Once you get it right for a particular material and machine type though you shouldn't have to mess with it.

Drag the box onto the shape so that it is centered on the vertical guide, and resize the height so that it clears the top of the shape and extends just past the horizontal middle.

Select both this rectangle and the background shape and use the "Arrange - > Shaping -> Back minus front" command to subtract the box from your shape and, viola!, we have a slot.

Repeat this for your second copy, except on the bottom edge.  Also make sure this box extends up past the center point and subtract it also.

Step 4: Flatten the Bottoms So It Will Stand, and Adjust for the Size of the Candle

This step technically could be done before or after adding the slot, or even before duplicating the shape in the first step.  I forgot to do it earlier, so we'll do it now. 

Make identical boxes across the bottom of each shape where you want to make a flat surface.  Likewise, draw a rectangle on the top (in this case between the pinching apparati) to make a flat surface for the candle to sit on.  When these nest together, they are going to make a plus shape, and often plus shapes sit more solidly with less surface contact area, so keep that in mind when you do this step.  For example, the crabs would likely sit more solidly on just their rear scuttlers than the scuttlers and carapace as I have done here.

Subtract those boxes from your shape, and then you're ready to cut!

Step 5: Cut Out Some Pinchy Crabs (or Shape of Your Choosing)

You can further chop your shape down to just a rectangle comprising the slot for the first test fittings to save material, or you can go for the gusto and just run the job!  This .2" veneered plywood was cut at a power setting of 90%, 500Hz, and speed 16% on a 120W Epilog, which took just a few minutes to complete. 

The smoke damage on the underside of the crab on the right can likely be removed using Fast Orange and a toothbrush.  Just brush it and wipe with a damp towel.  Alternately, applying a large sheet of masking tape (such as used for transfer paper for a vinyl cutter) to the bottom will prevent the smoke/flareup damage.  Just make sure it is a laser-safe backing material.

Step 6: Stack Them Together and Add an Object

Whew!  It all fits together!  And there's just enough space for this (LED) votive candle.  If using real fire, make sure you have it in a glass or metal holder so that your wooden object doesn't light up!