Building Prototypes Dan Gelbart part 3 of 18 Waterjet

Summary

Dan Gelbart explains equipment and practical modifications for building prototypes, focusing on the OMAX 2654 waterjet cutter.

Waterjet vs. CNC Plasma Cutter

The waterjet is presented as the more versatile option. It can cut a wide range of materials, including metals around 2 inches thick or more, and produces clean results. A CNC plasma cutter costs roughly one-tenth as much to purchase and operate, but is less versatile and limited to metals. Gelbart notes that plasma cutting can still handle many prototype tasks.

Waterjet Productivity Modifications

1. Sliding catch basket: Small parts can fall into the tank and get lost among the used garnet. A removable basket suspended below the cutting slats and moved with a pulley catches parts for easier retrieval. It is especially useful for thicker stock, where leaving parts attached by small tabs is impractical.
2. Laser alignment pointer: A homemade pointer fitted in place of the feed tube shows where the jet will strike. It helps align cuts, resume interrupted jobs, and register cuts to existing features. The shape of the laser spot can also indicate mixing-tube wear.
3. Splash guard: A half tennis ball serves as a compact guard, allowing cuts close to an edge while keeping the cut visible.
4. Clamps: Simple waterjet-cut clamps can hold material in place, particularly pieces up to about 1 inch thick.

Using a Plasma Cutter for Oversized Work

A portable air plasma cutter can cut holes in large enclosures or other items that cannot fit in the waterjet. Gelbart demonstrates using a waterjet-cut template as a guide, sized to account for the torch nozzle. This method is useful for quick, rough work; a CNC-mounted plasma torch can produce cleaner cuts.

Plasma Cutter Limitations and Safety

The demonstrated unit uses compressed air and household power and costs about $1,000 or less. It can cut steel up to about ¼ inch thick, while larger units may handle up to ¾ inch. It can also cut stainless steel and aluminum, but not nonmetals, and performs poorly on some heat-conductive materials such as copper.

The demonstration emphasizes using eye protection against sparks and intense UV light, and keeping flammable items away.

Main Speaker

• Dan Gelbart — presenter and demonstrator.