The Right Time for a CNC

May 5, 2003

By Kevin M. Padden

Every person that’s either a present or future owner of a stone fabrication shop asks this pointed question at some point in their career: when does it make sense to purchase a CNC machine and put it into everyday use?
Any answer is going to be easy to obtain (depending on whom you talk to), but the correct answer might take some time. A friendly sales rep will invariably tell you that “now is the time” to make the plunge. You’ll hear that kind of response at almost every trade-show booth that has a CNC machine on display.
It’s very easy to get caught up in the excitement of seeing the machine in action, hearing about how much you can save in man hours and tooling costs, and finding yourself getting out the checkbook to make a deposit on the perfect CNC. Unless you have an extremely high amount of self-control (or, in my case, a great wife who says, “No, dear — you can wait”), you may fall victim to the “I-thought-it-was-a-great-buy-at-the-time” syndrome.
Yet, if you’ve done your homework and thoroughly researched the different machines available, a trade-show purchasing decision can be a great money saver. The object of the game here is for you to make an educated decision on when the time is right for you to get a CNC.
Let’s digress for a moment and examine just what a CNC machine does, and how it can help your operation. A CNC machine – quite simply – is a robotic fabricating machine. It cuts, shapes, forms and, in many cases, polishes, too. The actual fabrication part of the job is done (for the most part) without the use of human hands. A piece of slab is placed in the machine and secured in place, and the CNC does the rest; however, there’s a lot of prep work done by the operator prior to the CNC actually firing up and creating a finished piece of work.
The CNC’s advantage is that it performs multiple and complex fabrication tasks; these are sometimes very difficult to duplicate by hand. A CNC can do repetitive tasks such as a commercial hotel project that includes, let’s say, 350 lavatory tops that are all 5’ 11 1/2” in length with one (or more) undermount sink opening, skirt and splash. This kind of project is made for a CNC machine.
And, with the national trend of stone fabricators using (and overall demand pointing to) 3cm-thick stone, a CNC machine makes a lot of sense.
Here are the questions you’ll need to ask yourself when you’re lying awake in bed thinking about a CNC purchase:
• What type of production will I be doing in the future that will warrant a CNC?
• Will I be doing large repetitive projects that require the same piece to be fabricated over and over again?
• Will I be doing exotic features, such as drain boards or multi-level milling and polishing?
If your answer to any of these questions is yes, then a CNC machine should definitely be in your shop’s future. The next thing you’ll need to start looking at is the incidentals that go along with the installation and operation of a productive CNC.
The biggest item you’ll need to procure (even before the actual CNC gets delivered) is a qualified operator/programmer. This single issue is probably the biggest reason there are more fabricators that start out with high hopes and good intentions, only to see their six-figure investment turn into a dormant paperweight. Regardless of the type, cost or manufacturer of your CNC, your operator will either make you or break you — and your investment.
Depending on your geographical location and job market, there may be a treasure-trove of potentially great employees out there. Without a qualified person to program and run your CNC, you’ll be seeing your operator every time you look in the mirror.
Don’t be afraid to look outside the stone industry for a qualified person to program and run your CNC. The automotive and aerospace industries are great places to look for someone, as well as your local technical-college counseling office. Be prepared to pay well for a quality person – either at the onset, or as they become more profitable for your operation. It’s also a good idea to gradually have other employees cross-train in basic operational tasks, so that when your star CNC person is out sick (as usual, on the same day a big project has to get completed) you won’t be up the creek.
Remember that the CNC does the work it’s told to do. You’ll need a person that not only understands the concepts of the CNC, but also can adapt to the natural characteristics of the stone being fabricated. That includes the placement of vacuum supports needed for the piece (to hold it in place while it is being fabricated) as well as noting any cutouts to be plotted on the computer and set up by your operator – prior to the start of the run.
Cutouts and other pieces can be plotted on a full-size digitizer that’s sometimes included with the machine, or available as an optional purchase. The digitizer records the job outline into computer language that CNC understands to make the piece.
The next area of consideration will be your expendable tool costs. The amount of actual cutting that a router bit will perform will vary greatly with the type of tool used. One type of router bit I examined recently will cut about 150 lineal feet before that particular tool is kaput.
Cutting-, shaping- and polishing-tool costs will need to be figured prior to you settling on any particular machine. The manufacturer can also supply you with the tools, and this is a great convenience; however, there are a number of tool companies that can provide competitive prices on expendable tools as well.
Another area of contemplation is the manufacturer that will supply the CNC. There are a number of excellent machine companies out there — both domestic and foreign — that can provide you with the right machine for the right price. What sets them apart from all the rest is the service and training after the sale. The CNC machine will do you no good if you can’t get parts, technical assistance and/or training.
In-the-shop considerations will be for an adequate electrical service, FRESH water (most CNC manufacturers recommend that recycled water not be used) and air for the vacuum requirements of the CNC.
It’s a good idea to plan out a materials-handling system to work with the CNC as well, so that you will reduce the risk of dropping a slab or finished piece on the work area of the machine. There are some good (and economical) jib cranes on the market that you can fit with a hoist and vacuum lift.
Once you decide that the time is right for a CNC, it will only be a matter of getting all of your incidentals in order before you can actually see the machine start paying for itself.
Happy Fabricating!
Kevin M. Padden operates KMPadden Consulting in Phoenix.