The Omax Waterjet is an amazing tool that has the ability to make precision cuts through a variety of hard and brittle materials such as marble. It's common to walk around scrap/demolition resale spaces and find beautiful slabs of stone (I found this slab from Urban Ore in Berkley) but it's a rare opportunity to have access to diamond saw tools. But a Waterjet not only can cut organic and interior shapes, the Pier's A-Jet head attachment further enables the machine for 5-axis cutting, giving it the capabilities to make angled contours between 0-60 degrees.
Step 1: Loading Material & Dry Run
To maximize the surface area of the tabletop, begin by measuring the stock, both its length and width, to define the largest diameter circle that can removed. Then proceed by modeling the part with the actual thickness of your material.
Normal cuts on the Waterjet are defined by two dimensional contour lines. Making a beveled part requires modeling in CAM the volumetric form of your design in its entirety including the precise angle of each tapered edge.
Follow the steps in this clearly Illustrated Instructable, Pier 9 Guide: A-Jet 5-Axis Cutting on the OMAX Waterjet, to move the file from CAD through IntelliCAM, Omax Layout and Omax Make. Then follow the instructions in the Pier 9 Waterjet manual to set up your stock and to set your work home coordinate system at the machine.
Make sure to lift your nozzle away from the bed on the z-axis and perform multiple dry runs to confirm that the nozzle will not run into your material or the clamps or the machine itself. In these two videos you can see the A-Jet head performing a dry run as well as the actual cut with the water raised
Step 2: Troubleshooting & Success!
Unfortunately the first run was unsuccessful due to a garnet clog in the small abrasive hopper. Luckily there is an Instructable for troubleshooting clogs. Once the abrasive flow is properly pressurized, thanks to shop staff coming to the rescue, simply run the file again. Unfortunately in this case the work coordinates from the first cut were lost, which makes it impossible to line up the second run of the file to the first failed attempt, so I simply scaled down my model in Omax Make to make a smaller table top.
Step 3: Sanding
The water jet abrasive leaves a very precise and sharp cut in stone so make sure to wet sand your edges. Marble is also a subtly porous material so wipe off the sanding abrasive from the surface of the marble so that it does not get permanently absorbed.
Step 4: Voila!
Stack some books underneath to support what you made!