HOW TO EVALUATE ENTRY LEVEL PLASMA CNC MACHINES

While there are quite a few offerings in the lower cost end of the market, I will impose an upper price limit of about $20,000 for the sake of identifying the CNC plasma machines being discussed from this point forward. That price includes plasma, computer, and anything necessary to cut metal successfully. Let’s look at what you can get for that price, what can be expected in terms of tolerance, throughput and cut quality, and how easy it is to learn and operate these machines.

SIZES, PRICES
While I am not promoting any one brand of these entry-level CNC machines that are currently available – and there are probably 15 to 20 (or more) manufacturers of these low cost cutting tables – I will briefly mention three brands just for discussion purposes. When you search for low cost CNC plasma machines, the responses that you will see most often are PlasmaCam and Torchmate.

PlasmaCam offers two basic models of machines sized with cutting areas of 4 ft x 4 ft and 5 ft x 10 ft, while Torchmate has models and sizes that start at 2 ft x 2 ft and go up to systems that can be 8 ft or more wide by an almost unlimited cutting length. These machines are typically broken down and shipped in a crate, and can be assembled in a few hours using normal hand tools.

I have assembled both PlasmaCam machines and Torchmate machines, and I would equate the difficulty with that of assembling a gas grill from the local department store, i.e. quite easy. Both had very detailed instructions and the electrical and computer connections were mostly plug and play, with a few exceptions for making connections to the plasma cutter. The plasma cutters can be purchased from these companies or from your local welding supply distributor. Each model offers options for using a hand plasma torch or a machine torch (straight barrel design). I personally prefer the use of a machine torch on a machine application. This is slightly more expensive, but much easier to square to the plate, and much easier to electrically interface.

The third brand is called CandCNC Electronics, which provides a different approach to the low cost CNC plasma market by offering a variety of kits that include drive and torch height control electronics, the related CAD drawing software as well as post processing software. This approach is for the “do it yourselfer” that has the skills to fabricate the metal frame and moving components of a CNC cutting machine, then bolt up the drive motors, plug in the electronics (as well as a computer and a plasma system) and have a truly homebuilt system. This is much more difficult to build compared to those other assembly-only options, but for a skilled metal fabricator that may already have the tools, this can be a very low cost CNC machine build.

Prices? The above mentioned systems start at under $1500 for the electronics and software packages (remember, you still have to buy mechanical motion components such as gears, linear bearings, steel, etc., plus a fair amount of design time and build time), while the smallest versions of the “prebuilt but assembly required” machines start at under $3000 for the 2 ft x 2 ft machines and can run to the maximum of about $20,000 for larger machines.

Don’t forget that you must add a plasma system and a PC-based computer or laptop to these prices!

WHAT ELSE IS NEEDED TO CUT METAL?
With the Torchmate and PlasmaCam, assuming you have a basic understanding of CAD drawings and have read the operating instructions, you can be cutting metal in a few hours. With the DIY kit, after you finish fabricating and building the machine.

Fume Control is an absolutely necessary evil with any plasma cutting system, so you must fabricate either a water table or water tray or a downdraft system with an exhaust fan for ducting the fumes/smoke outside or for filtering. Water tables/trays work well, although the splash back that is common can provoke rust and stains and have slight effects on cut quality in terms of edge roughness and dross formation. Downdraft systems are a bit more costly, generally consisting of enclosing the base of the machine, installing a blower fan and ducting the fumes outside or to a filtering device.

There is, of course, a bit of a learning curve with the software. Most systems import the industry-standard .dxf drawing file. Or you can draw your parts at the machine on the computer using the including drawing package. Ease of use depends on your familiarity. I bought one of these machines about ten years ago and had never done any CAD drawing prior to the purchase. After assembling the machine, I sat down with the tutorial in the operator’s manual and had my first CAD drawing (a simple rectangle with a couple of holes!) drawn in about 45 minutes. I had an advantage in the fact that I had been working for a plasma manufacturer for about 20 years, so setting up the cut parameters was easy for me. Today, drawing in CAD and cutting with these machines is second nature.