A couple of weeks ago I worked in tandem with another sign shop to install a fairly large all-metal sign. Matt, the owner of that shop, a friendly competitor, used his sign crane to lift the sign, and I used my manlift to position me for the hands-on part of the installation.

While he was there, Matt looked over the way we had built the sign posts, secured to large leveling bolts welded to the top plate of short stubby posts that were concreted in the ground. Both sets of plates and gussets were made from ?” thick steel, and all cleanly and identically cut on a CNC plasma table. The welding, done by my 82-year-old dad, was obviously strong and he was impressed at how well built the sign structure was, and asked me how we made the parts.

Of course, making the parts was the easiest thing, since all was cut on a high definition CNC plasma table, and in fairly short order. Since our sister company does that type of work, I volunteered to have them make any structural parts he needed fast and at a fair price anytime.

Today, with the computer driven equipment that is available most any place, it simply does not pay to do much cutting of steel, or anything else, by hand. And these CNC machines of various types have certainly gotten better over the years.

Most sign shops are familiar with CNC router cutting, and maybe a bit less familiar with other types of computer controlled cutting, but let’s take a little time and look at what a CNC plasma cutting table can do, and how best to use this type of technology for sign shop work.

Fortunately, to take advantage of a quality plasma table this day and time, one doesn’t have to own one as the proliferation of this type of machine has made finding a subcontractor easy to do in most areas of the country. AtRick’s Sign Co., we would merely have to walk across the street for finding a source for high-quality plasma cutting, but most sign shop managers would not have to look far.

Nowadays, there are standard plasma tables, and also high-definition plasma tables, which can cut with something approaching the accuracy of a waterjet (though not quite). All of this is really amazing as the stream that does the cutting is “plasma,” or a gas-like matter caused by the combination of a stream of an inert gas and high-voltage current, and the plasma created can reach temperatures of 25,000 degrees Celsius or more.

For sign shops, plasma cutting can be used for the obvious purpose of accurately cutting plates, flanges and gussets from structural steel, and also for cutting decorative pieces that will be welded to a larger steel structure, and even plate steel letters like some of the examples shown here. With the accuracy of many of today’s plasma tables, fairly complex and delicate items can be cut if the computer file created to produce the items is prepared correctly.

In this case, “correctly” means having the right tolerances for small inside cuts, reasonable line thicknesses and so forth. The scroll work we recently produced for a small custom sign makes a good example of what is possible with a high-quality CNC plasma table.

After preparing a file that I knew would test the limits of the Messer Plasma Cutting table we would be using, we cut a test item from .25” thick mild steel. The machine cut through the steel like it was cutting butter, but the final quality of the cut was less than ideal, due to the faulty computer file I had created.  The inside cuts were too tight (at least for the standard cutting tip we were using), and some of the line thicknesses were so delicate as to cause some cutting problems as well.

With the second computer file, which worked beautifully the first time, I had merely made sure that all line thicknesses were something close to 3/16” thick, and the inside cuts and dead end radiuses were .15” or larger.  Maintaining these simple parameters, at least when working with .25” thick steel, were all that was needed to allow the plasma table to do some beautiful cutting on my decorative parts.

The four decorative scrollwork pieces were all identically perfect, and the small amount of slag that a newer high-quality plasma table leaves on the back is not a real factor as it is very easily removed. Because these were steel, they could be welded directly into the square tube steel frame we had built for this job. The entire frame was blasted and heavily powder coated for extreme durability.

There are also times when a client requires letters being cut from steel plate, not aluminum, and that is another place where a modern plasma table with shine. For letters that will weld to gates, or weld to steel entrances (as in over a park or cemetery) and to be cut from mild steel, or any letter application at all as long as the steel gets a high-quality powder coated finish in the end.

Such lettering can certainly be done with a CNC plasma cutting table, over a waterjet, with no noticeable loss of quality and much cheaper and faster. And fast may be the key word, as plasma cutting will average 5 to 10 times quicker than waterjet cutting on steel of the same thickness.

In years past I have made the mistake of having work cut on a waterjet, when the quality of a plasma cut would have been perfectly fine and at less than half the cutting cost. Or even wasting time making base plates or structural parts by hand, drilling them on a drill press and so forth, which is really a serious waste of time in light of how fast and accurate this work can be done on a good plasma table.

So, when the type of work at hand means a router won’t do it, and a waterjet is overkill, there is a large middle ground where the best tool for the job is going to be a modern CNC plasma table, and you can almost be certain there is one nearby and ready to be put to work, and it will likely save your company some money in the process. What’s not to like about that?