Control Design – May 2019

easy access and filling. Buckets were

also integrated into the machine to col-

lect used abrasive (Figure 2 ).

Normally, the wet, used abrasive

collects at the bottom of the tank, and

it’s necessary to remove the bed, drain

the tank and shovel it out by hand. We

developed a suction system that sucks

the abrasive from the bottom of the

tank and dumps it into buckets housed

within the enclosure that can then be

easily removed. Garnet (crushed rock) is

the recommended abrasive. Since it is a

naturally occurring substance, it’s safe

to throw the used material in the trash.

Integrating all of these and other

systems into one enclosure, making the

machine compact and contained, was a

nontrivial design problem.

Profile cut

The Wazer waterjet is controlled by a

custom controller designed to run a cus-

tom flavor of the open-source Smooth-

ieware firmware. The controller has the

drivers built-in to run stepper motors, as

well as all the digital inputs and outputs

to run the machine.We developed our

own Web-based software called Wam

that converts a drawing file into a G-

code cut file. A new cut file is created by

importing a drawing exchange format

created in AutoCAD or similar (DXF) or

a scalable vector graphics created in a

graphics programs such as Adobe Il-

lustrator, Corel Draw or similar drawing

file (SVG) into our software.

Once the drawing is imported, it can be

rotated and oriented on a virtual cutting

bed. The material, thickness, cut quality,

such as course or fine, and cut path, such

as outside, centerline or inside, are also

specified in the software. The output

G-code file contains all the information

the Wazer needs to cut the design in the

chosen material and is loaded onto the

machine through a USB connection.

There are basic controls and an LCD

screen on the waterjet. An operator uses

these controls and display to select the

cut file, start/stop the waterjet operation

or run a maintenance protocol.

Make the cut

There are many applications were

CNC-like tolerances are not needed

and a waterjet works well. In general,

avoiding CNC, at all cost, helps the

bottom line in manufacturing. And

it’s usually cheaper to work with sheet

metal. In an example application, we

converted a standard bike into a belt

drive. The waterjet was used to cutout

the pulleys and gear teeth that en-

gaged the belt from ¼-inch aluminum.

As with any waterjet part, after a cut,

there may be a burr on the bottom edge

that needs to be sanded off, and the

edges may not be perpendicular. Also,

the holes, as a final pass, may need to be

drilled and reamed and may not be suit-

able for press fit. However, the bracket

outer geometry will be within approxi-

mately .010-inch tolerance, and the holes

will be in the proper location. Brackets,

for example, can be quickly made.

The cut produced by the water stream

is roughly 1 /16 inch (1.5 mm) in width,

so that coincides with approximately the

smallest feature—internal diameter or

internal line width—you can cut.

By far the most expensive component

in a traditional abrasive waterjet is the

high-pressure pump. These subsystems

operate at 6 0,000-90,000psi, generate

incredible amounts of cutting power,

and cost tens of thousands of dollars. We

have figured out how to maintain useful

cutting performance while significantly

reducing the water pressure. So sure, we

can’t cut through 2 -inch-thick steel, but

do you really care?

40 / May 2019 / ControlDesign.com

motion control

Wazer in China

Figure 3: Wazer assembles the final product at its U.S. facility, but many team members lived in China for

many months to set foot in the factories of its subcomponent suppliers.

(Source:

Wazer)

CD1905_38_41_CaseStudy.indd 40 4/29/19 12:26 PM