Centroid article in CNC West.

Anaheim, CA, is the home to a 10,000 sq. ft., 10 employee industrial engraving and silk-screening shop that caters to such diverse engraving needs as those of Callaway Golf Clubs and Lockheed Aerospace. A few years back, the small company found itself in a very typical equipment quandary.
"We were depending on our 10 year-old Sharnoa vertical kneemill that still had its built-in, original control," relates H.W. Christes' Engraving CO. owner, Arlen Cannon. He took over the 50-year-old specialty job shop in 1983.
"The trouble was that in spite of being a really great machine... especially for engravers and moldmakers... over time we must have let go eight different operators who just couldn't learn to program it and show up to work, too. Also, the original control really couldn't handle the CAD/CAM file sizes we often have to use. Soon it was obvious that the machine's entire programming operation was too slow, and it had completely limited our CAD/CAM milling capabilities," Cannon concluded.
No matter how accurate the cutting abilities of a CNC mill, a weak control negates the machine's usefulness altogether. "Remember we may program and set up nine hours for a job that cuts in 15 minutes," Cannon says. Such complex jobs are simply not possible with limited control memory or insufficient computing power, i.e., lost business.
Nonetheless, the CNC mill in question was capable of the precision millwork the shop actually needed and wanted more of, such as precise 50,000 RPM spindle engraving.
Does this problem sound familiar?

Overcoming Control Obsolescence
As many in the industry can attest, the available solutions to such typical control obsolescence problems are not always entirely satisfactory.
Buying a new and comparable CNC mill with the necessary features can be a prohibitive capital expense for a job shop the size of H.W. Christes, especially if that large an outlay turns out to have been avoidable after all. The other available solution for replacement of an outdated CNC is a machine and/or retrofit; but experience demonstrates that such retrofit projects can turn into piece-meal efforts with uneven results.
Unfortunately, though many CNC control-retrofits are available on the market, the job of successfully matching machine, motion systems, servo systems, CPU's and PLC I/O boards into a unified end-result that is easy to operate in is a real challenge.
This fact was apparent to the engraving shop, too.
"What we needed was a real comprehensive CNC control solution," Cannon explains, "that would allow us to run all of our CAD/CAM programs... and still provide that all-important ease-of-operator-use-factor." After all, what good is the fanciest CNC machine tool setup if no one can operate it but a systems engineer?
The shop was pleasantly surprised to learn that an answer to their mill-control problem was actually close at hand. Luckily, the man who serviced the Sharnoa mill in question... Doug Laursen of Machines in Motion, Chino Hills, CA... was able to furnish such a package.
The real bonus: the new control system has doubled that particular vertical mill's productivity in the process.

More Than a Retrofit
"We now have a Centroid M-400 control package on that very same Sharnoa vertical mill," Cannon reports happily. "It runs all our 3-or-4 axis CAD/CAM routines, including Gibbs and Mastercam."
The Centroid unit is a ‘bolt-on', pre-wired, PC based control panel that adjusts to operator positioning. The M-400 model features a very clean, sealed keyboard, color LCD screen, and electronic handwheel among its user-friendly controls.
"Memory is no longer a limitation," says Mike Hiner, one of the shop's engravers. This is possible because the Centroid system has its own built-in hard drive, 3.5" disk drive, and RS-232 coupling."
"I used to have to run up to my office for programming," Hiner explains, "and found that the mill was idle more than it was running. With the new control, everything is right here, and I can do all programming and milling on the spot. That's lots more efficient."
The most complicated CAD/CAM part-programs may be now loaded by an operator directly into the Centroid control panel by popping in a floppy disk; or alternatively, jobs can be downloaded from another PC via a RS-232 port connection.
Graphical G-code programming and standard G-codes are also built into the control.
The shop's operators have flourished comfortably with the new control without having to "master ancient Greek," according to Hiner. This is in large part due to the simplicity of the system, coupled with Centroid's easy-to-follow training videos.

M-400 Milling Control
The shop's new M-400 milling control is one of several models that Centroid, of Howard, PA, produces for use on CNC knee mills, bed mills, and machining centers. Founded in 1980, Centroid designs and manufactures motion control devices with stepper or servo motors and control, low and high power drives, and stand-along and PC-based components.
Two other Centroid models, the M-15 and M-39, offer controls for mills in slightly different formats.

Special Milling Controls
"The results we have is a fully-CNC mill with capabilities that have greatly expanded the jobs we can do." Cannon emphasizes.
The shop floor programming that Centroid's software employs has canned cycles for various geometries: graphics with 2D and 3D; and zoom, pan, and rotate commands. Off-line programming software is also available. Computer-controlled spindle, flood, mist, and lube are incorporated function.
Mastercam, a CAD/CAM software well known in the industry, is included in this control to create toolpaths. Automatic G-codes generations, or the ready of DXF,IGES,CADL and ASCII file formats are other parts of Centroid's contribution to the revitalized mill.

Old Mill, New Life
"Now our trusty old mill has all the macros," Cannon reports on new CNC control. "We can easily create a subroutine out of any program, mill the same program at any number of different locations, or copy repetitive toolpaths to save lots of mid-numbing programming time." Errors are reduced as results, naturally.
Likewise, the Centroid control works with coordinate systems to set up vise with easy menus, provides offsets for up to 6 fixtures, sets travel limits, and remembers all zero positions (even if powers is lost). It also uses a fixed machine home position for easy of use.

Unlimited Part Program Size
The new controls' 600+ megabytes of storage allows unlimited program size, thus eliminating the memory limitations imposed by many similar CNC controls. For example, 3D surfacing is possible without the need for DNC dripfeed, permitting continuous milling at 600 blocks per second.
Additional options that may be included in a Centroid control installation include digitizing software, utilizing a touch probe to digitize parts...turning the CNC mill into a copier. "With the digitizer you don't need an external PC to store information or output to CAD/CAM. Better yet, you can digitize parts, then mill them," one operator commented.
Two types of probes are available with cable and stylus: conductive and nonconductive. These may be used as reference tools or fixed detectors. With the optional probing cycles, tool measurements are automated, and time is saved setting up parts, as the system finds the center of bosses, bores, slots, webs and pockets, as well as part corners.

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