CNC specialist The Lincoln Electric Company explains the Seven Deadly Sins (or should that be Seven Common Errors?) that engineers may commit when purchasing a CNC cutting machine for their company.
1. Buying a machine with a cutting capacity you will outgrow
The most limiting factor of any CNC cutting machine is the size of the plate that can be cut without interruption.
Since most material comes in at least a 4' x 8' size, your cutting table should be at least that size. Smaller tables require you to pay for the added expense of having your plates sheared to size, or worse yet, having to wrestle with a plate that is larger than the surface that is supporting it. You have to cut part of the plate, and then move it to cut the rest.
When the shape you are cutting is longer than your cutting table, it is terribly inconvenient. You have to stop halfway through a cut, move the material, making sure to align it on the table so the second half of the cutting process starts just where the first half left off. You generally need to fabricate fixtures into which your material slides. Since you will be working with different sized plates, and often remnants, this is very time consuming and tedious.
This re-positioning of the plate on the material is sometimes called indexing. Having a table big enough to cut an entire plate saves perhaps 1/3 of your time and effort, and always produces better results.
CNC machines are available in a wide variety of sizes to suit your individual needs. We don't restrict you to the few sizes we feel like producing. Our tables come in 4'x4' all the way up to 11'x40' – and everything in between.
2. Buying a machine that can only do one thing
Whenever we buy a tool of any kind, it is impossible for us to foresee all the uses to which we will put it over the years.
When buying a CNC cutting machine, it is sound reasoning to buy one with as much versatility as possible. At a bare minimum, your machine should be capable of both plasma and oxy-fuel cutting. Oxy-fuel produces better results in steel 1/2" and thicker, and can be used to cut steel up to several inches thick.
You may think you will never cut anything 1/2" thick, but do you know for sure?
It is even better if you buy a machine that can be also used for spotting holes for drilling, drilling aluminium, cutting shapes in the side or ends of tubing, routing of wooden shapes, engraving, etc. You never know for sure what your future needs will be.
3. Buying a machine from a new company
The best way to ensure that you will be able to get continued technical support, replacement parts, new accessories etc for your machine is to buy it from a company that will still be here when you need them.
Many new companies go under in the first year or two. Don't let your investment go up in smoke if that were to happen to the manufacturer of your system.
We are constantly getting calls from owners of machines built by companies that have gone out of business. Since they can no longer get parts, they have no choice but to totally retro-fit new electronics.
4. Trying to build your own machine
Most people who have a need for a CNC cutting machine are metal fabricators, who given enough time, could probably design and build the mechanical part of a coordinate drive cutting machine.
However, just because you may be capable of doing something doesn't necessarily make it the smartest thing to do. While the physical machines may look simple, it took us hundreds of hours of experimentation, construction of prototypes, and modifications before we felt they were ready for the public. Since then, our machines have undergone further refinements based on customer feedback and suggestions.
Spending hundreds of hours of your time and ending up with an inferior machine with no warranty is false economy. The time would be better spent using the machine to do what you intend it to do. Those who want to save money by doing part of the fabrication can do so by purchasing one of our Torchmate CNC gantry kits.
5. Buying a machine without an electronics warranty
The electronics supplied with a CNC cutting machine are its heart. Like a new computer, if something is going to go wrong with them, it usually happens right away. Make sure that you have a parts and labour warranty to cover any manufacturing defects that might surface during the first year.
Like automobile dealerships, some manufacturers sell their products at what seems like a very reasonable price, and then make up for it on service and repair charges. Be certain of what kind of warranty comes with your electronics.
6. Buying a machine without free telephone technical support
While manufacturers of CNC cutting machines try to make their instructions as clear and understandable as possible, chances are that you will at one time or another need to call for technical support. Make sure you don't have to pay for it. You are paying several thousand dollars for someone's product. You have the right to assistance if you need it.
It is good to know that there is someone who is only a telephone call away that can answer any question that might come up.
7. Spending more than you need to
We have all heard the expression "you get what you pay for". This is certainly true in our industry. It is probably possible to buy a CNC plasma system somewhere else for slightly less money. The question is, how much less, and what are you getting for your money?
You can buy a tool chest full of imported tools for less than the cost of quality American-made tools. However, tools last a long time, and most of us would rather spend a few extra dollars and not regret our purchase later.
Time is money. How much is yours worth?