Here is a recent wood cutting project I worked on with my nephew Elliot. We started out with a CAD drawing of the base of a guitar. It was in three sections. A thin section for the top, a thick section in the middle, and a thin layer on the bottom:
Guitar drawings in OMAX Layout (waterjet CAD/CAM system)
The wood in this case was Peruvian Maple, which turned out to be about $500 worth for just barely enough wood to do the job. So, we were careful! Peruvian Maple is typically used for flooring because of its hardness and durability.
Chalk outline of wood prior to being cut by waterjet
We started by outlining the spot on the wood where we wanted to cut. For aesthetic reasons, we wanted the grain orientation to be lined up in a certain way with the shape of the guitar.
Dry run of waterjet cutting (running with jet turned off to check path)
We lined up the material under the nozzle, and rotated the tool path so that when dry ran, the nozzle followed the chalk line previously drawn. “Dry running” is running the machine through the path with the nozzle turned off. It’s a great way to verify that it’s going to do what you think it’s going to do, prior to actually cutting your expensive material. When you only have one piece of material to do the job, and a replacement has to be shipped 8,000 miles after being carved out of the rain forest, you do a dry run first.
Cutting in progress on one of the thinner pieces
You might giggle a bit about the above fixturing—just a bunch of scrap with weights, but it worked fine and was easy to do. Perhaps we over-did it a bit, but when in doubt put more fixturing on than needed. Waterjets don’t put much load on the part being cut, but material can still shift around, and since we only had one chance to make a perfect cut, we fixtured a bit on the paranoid side.
Notice also that cutting was done above water, to avoid having the wood absorb too much water. While waterjet cutting is usually done under water to reduce noise, cutting above water is easily done—provided proper ear protection is worn. The waterjet stream is traveling at about the speed of sound as it exits the nozzle and is very noisy.
Cutting in progress
The final cut around the outside
In the above picture, the middle of the guitar is being cut (shown in the next picture). A key thing when cutting with waterjets is to cut the outside of the part last. Once the outside is cut, the part can shift or tilt, so saving the outside until the end makes sure you get the best possible part.
Finished wood cut-outs
Waterjet slugs after cutting
You might note that one thing cool about waterjets, is that you have useful left overs. With a $500 piece of wood, the above scrap is worth something.
Elliot holds his masterpiece
The guitar was equipped with a carbon fiber neck, and a bunch of electronics, then hand polished for a few days. The sound is incredible.
A couple of notes about cutting wood with a waterjet:
- Wood cuts easily and quickly.
- Wood gets wet, which causes it to swell and deform. We took care not to get it wetter than necessary by cutting above water.
- Wood is soft. We cut over “waterjet brick” (the plastic grating you see in the above pictures), so that the jet would not ricochet off the typical metal slats, and mar the bottom side of the wood.
Techniques for working with brittle materials, such as granite and marble.
When cutting laminated materials with a waterjet, you need to use some techniques to keep the water from getting between the layers and ruining the material.
A discussion about how to cut glass with a waterjet to minimize broken and chipped parts.
Parts made by waterjet
Four pages of various parts made by waterjets, plus some pictures of waterjets and screenshots of software.