I really enjoy working with the laser cutter at TechShop. I am constantly amazed at the tiny detail it can render. And while it's running the motion is mesmerizing.
I wanted to cut some images that showed off this incredible device, but I'm not an artist. I could use images I find on the web, but those really belong to someone else. I wanted to find a way to make some detailed artistic projects that I could call 100% my own.
Last month I hit on the perfect idea - use my own photographs of nature! The subjects come with infinite detail, and the copyright belongs to me.
I start with picking a leaf from our garden and end with a third clear coat. Along the way we'll use a digital camera, Corel Draw, and the Epilog laser cutter at the Menlo Park TechShop.
You can see my other projects at Shrimpware or read more about me on my web site.
Let's get started!
Step 1: Choose a Leaf
I added the photo to Dropbox and it magically appears on my PC.
Step 2: Turn the Photo Into a Solid Area
I create a new project and use File/Import to bring in the photo.
Using the corner handle I resize my large photo until the leaf is about 6 inches across.
Use the Effects / Adjust / Desaturate to get a gray image.
Use the Effects / Adjust / Brightness Contrast Intensity to set Contrast to 100%.
Now we have a solid black image of the leaf.
Step 3: Trace the Outline
Select the image and select Bitmaps / Convert To Bitmap.
Next select Bitmaps / Outline Trace. This will bring up a dialog with a number of controls. The top image is your current image and the lower window shows a preview of the outline. The Outline Trace function will make curves around each color in your image - to some degree. Because we've made the image almost pure black and white we will get one curve around the entire leaf.
Outline Trace offers a couple of choices. The higher the value of Detail, the more different shades of color will be used - each color shade getting its own outline trace. Smoothness affects how much small detail is constructed around each color shade. And corner smoothness affects whether there are sharp points in the resulting outline. The preview window makes it easy to move the sliders and see the effect.
For my leaf I set Detail to the minimum which gave me just one curve. Smoothness was moderate, and I did not smooth the corners as I want my leaf to have some points on the edges. You should play around with the settings until you find an outcome that you like. In the attached photo I have zoomed in so I could watch the effect the settings had on the edges of my leaf.
Step 4: Create Missing Parts
I created a new layer below the current layer. I then selected and dragged the leaf photo into this layer.
I now used the BSpline tool to create an outline of the stem. In the photo you can see the first BSpline for the left side of the stem. Create one for the other side of the stem. Then select each and do an Arrange / Convert To Curves. This makes the BSplines suitable for joining to the larger outline.
Step 5: Weld the New Parts to the Main Leaf
Use the Node tool. Hold down control and select both the stem curves and the leaf outline curve. The first photo shows them all selected.
Now select Arrange / Shape / Weld and the curves will be joined. But look at the weird fill! Here's how you correct that.
First, using the node tool double click on every little square on the leaf outline that is between the leaf and the new stem. The close up shows this part of the drawing. The next photo shows the situation when all the nodes are deleted and there is just the line left. I've single clicked on that line to select it - you might see a little white dot on that line. Now press the delete key to remove that line.
This next photo shows the drawing after the leaf outline has been broken by deleting the line. You can see the curves of the stem coming up to meet what is left of the leaf outline. Note that they do not meet perfectly. The photo shows a close up of the stem and leaf meeting. Use the Node tool to double-click and delete all the extra nodes. Then, as a final step, click and drag the end point of one curve onto the end node of the other. Make sure the pop-up advice says "node" before you release the node you are dragging. Now the curves are connected. Repeat this on the other side of the stem.
We now have joined the stem to the leaf outline.
Step 6: Clean Up the Outline
I've found that the auto trace function can leave some funky loops and odd points in the outline. If you do a veneer cut with these oddities it will come out with some gaps in the final product. I've learned that I have to visually inspect the entire outline at a pretty high zoom to find and correct these. All the correction happens using the Node editing tool.
The first photo shows a "small feature". This is bit that would be hard to cut in veneer, and does not really represent the true outline of the leaf. To fix this I deleted nodes in the area by double-clicking on them until the outline looked like what I thought the leaf should be. You can see the corrected outline in the next photo.
The next photo shows a feature that is correctly part of the leaf, but it is too small for a veneer cut. In this case I might drag one of the nodes away from the other. I might then select a blue node handle and adjust the curve in the area. There is no right answer here. You don't have to be much of an artist, just make the changes that seem OK to you. These are tiny features that add to the overall effect of the leaf, but only at a small scale.
Finally, I also look for features that are just too pointy. In this photo you can see where the curve is so twisty that the line shows a bit of a skip. I just delete these points - as shown in the last photo.
Step 7: Add the Area
Select the outline and Object / Properties and make sure the line width is Hairline. This tells the laser cutter to cut this out.
Select the Fill tool and add color to the outline.
We end this step with a leaf image that is ready for the laser.
Step 8: Test Cut With Paper
Now I examine the cut out for issues. As you see in the second photo there was a small part that didn't cut through. Why not? Heck if I know. I went into CorelDraw and fooled with that area a bit. A second test cut worked fine. Hard to say what was wrong.
With the fixed drawing I cut another leaf out of six ply mat board. We'll use this in the glue step.
Step 9: How Deep and How Big?
I made a small test drawing in CorelDraw. The first line is four black squares, all the same size. I set the TechShop's 45 watt Epilog Helix laser cutter to raster scan at 600 dpi, speed 60%, power 90%, and I set it for 3d mode. I raster etched all four once. Then I selected the right hand three and etched again. Then just the last two to do again. And finally just the right hand box for one last raster etch.
This process gives me four boxes, each etched a different number of times.
I'm using a sheet veneer I bought at Southern Lumber in San Jose. I cut a small square of my veneer sheet and dropped it in each square. You can see that the two pass is not deep enough. The three pass is better. The four pass raster etch is just perfect!
I also wanted to test the size fit. The second part of my jig has four boxes but the outside line of each box is done in a different line width. This would give me some wiggle room to fit my piece; if the veneer was a little wrinkled I might need a little slop to fit the veneer flat. Based on the last test I raster etched these four times. (Note that the screen capture shows the area as red so you can see how the line width affects the perimeter size. When I etched these I made each box black.)
As it happens, this veneer is very flat and the hairline edge size is a perfect fit - the veneer square almost snaps into place!
Step 10: Raster the Leaf
Based on our previous tests, I raster etch the leaf four times. Then I vector cut it out. The whole process took 25 minutes.
Step 11: Select and Cut the Veneer
The veneer is thin and can move in the laser cutter table. I use the remains of the leaf cut out to hold it in place. I also drop a weight on the remains. Make sure the weight is in a place that the delicate laser cutter head will not hit it.
This cut took just a few minutes. I carefully lift the veneer leaf out of the laser cutter and place it into the etched image. This is the moment of truth. Holy cow, it fit like a glove!
Step 12: Glue the Veneer
Using my finger I spread Elmer's Wood Glue on the back. Just a light coating and I make sure to spread it to the edges of the leaf. If you get a bit of glue on the front it's ok.
Now carefully place the veneer into the wood hollow and massage it into place. Starting in the center press your finger very firmly and run it to the edge. Keep doing this until you know that the veneer is really held in place.
Position the mat board cut out on top of the veneer. Carefully place a flat board on top of it and then put a weight on top. Leave it for 10 minutes.
Now remove the weight and covering board. Use some spring clamps to hold the edges of the mat board tightly to the underlying wood.
An hour later you can remove it all and look at your work.
Step 13: Sand and Finish
First I use 60 grit and sand it until the surface is as even as I want it. Then a sanding with 150 grit to get it smooth. Then a final sanding with 320 to be really, really smooth.
Remove all the dust with a tack cloth and apply a coat of clear finish. I used Verathane. Water based finishes can raise the grain, so I used an oil based finish. I also use foam brushes because they are cheap and I can just toss them away.
Let the first coat dry for at least 3 hours. Then lightly sand with 320 grit and coat it again. Do this four times and you will have a lovely finish.
In the close up you can see how nicely the veneer and wood base fit.
The final product is a thing of beauty. But the best part? That copyright at the bottom says it all - this art work is all mine.