Step 1: Make a Mold for Concrete Slab and Cast With Concrete!
This is not my photo, but gives a good idea of what happened during this step.
Using wooden strips and a plywood panel for the bottom, a wooden mold was constructed for a concrete slab. This will form a type of open box, only with the walls much shorter. The thickness used in this case was .5". Clamp the strips securely to the wooden panel with clamps, they do not need to be glued.
You can make this slab whatever size you want, as long as it fits inside the waterjet cutter. Remember, you will use this slab to cut out symbols and letters later. The thickness used in this
Mix the concrete according to the instruction on the package. A recommended concrete product is linked in the "Materials Needed" section. If the cement does not give instruction, it is good rule to add enough water to the concrete so that it becomes a fairly viscous liquid. Some cements call for aggregate when mixing; however, this is not necessary.
Allow the slab to cure. Cover the open areas of the concrete with plastic wrap to decrease any shrinkage from the curing. Once the slab is done curing, you can sand it with regular sand paper. It is important to sand any uneven surface as this could cause complications with the waterjet later on.
Step 2: Make Outline and Export Into .dxf File
In Adobe Illustrator, make the size of your artboard the same as your concrete slab.
The character size used is around 3" x 2.5".
The font size is 221pt.
With the text selected, click on Type->Create Outline. Now the characters should change into a path, and you should be able to see the anchor points on the path.
Go to File->Export, and then select "AutoCAD Interchange file (dxf)"
The font used is a Japanese font called CP font, here is the download link:
However, you can use whatever font or symbols you would like.
Step 3: Load the File and Concrete Slab Into the Machine
Load the .dxf file into OMAX software.
Set the lead I/O, make sure the waterjet won't punch a hole on the part you want to keep.
There is no concrete setting in the OMAX software. So, a white marble was used in the material selection. The thickness of this concrete slab is .5''.
Put the slab into the machine, and make sure you wear gloves. The water may be dirty in the waterjet machine.
Clamp the slab on to the machine tightly.
Check the distance between the waterjet head and the slab. Make sure the head will not hit the slab later.
Step 4: Start Cutting It!
Go! Make sure you have enough abrasive in the bin and keep your eyes on it in case something goes wrong. Never leave the machine and make sure there are others nearby in case their help is needed.
Step 5: Add Lasercut Plywood on the Back of the Alphabet
Prepare the lasercut file in Illustrator and cut the plywood with lasercutter.
You can edit the file used with the waterjet; I put some holes on the alphabets in order to fit the magnets. Make the holes the size of your magnets.
Here is the link of the magnet I used. They are 1/8" in diameter:
I used 1/8'' birch plywood for the letters.
Finally, put the wooden lasercut alphabet, concrete waterjet alphabet, and magnet all together by using epoxy.
Step 6: Add Some Color
You can also use acrylic paint to color the letters and symbols to make them stand out.
Step 7: Done!
Finished! Put the concrete magnet on the shelf and enjoy it!