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Build Your Own Cnc Plasma Table – I’ve always thought that a CNC plasma table would be too dangerous or too expensive to run in my home shop, where I don’t actually build anything for profit. While a plasma table does come with some unique challenges, like dealing with the metal fumes that are generated, I can officially say that I was able to build one “affordably” (< $4k) and safely. And boy am I glad I did! Plasma cutting projects in mild steel have been the most fun I've had in quite some time. I might even say I like plasma cutting more than 3D printing (shocking, I know). Unlike the milling machine, plasma-cut parts don't require careful planning. I just load a .DXF file into my favorite CAM program, generate some G-code and the plasma cutter is off to the races.
While there are many affordable CNC plasma tables on the market, it’s important to remember that you get what you pay for. I’m usually able to squeeze a little more mileage out of my money by buying my own parts and building the fixture/machine. However, this isn’t always true, especially when you break components during construction or buy the wrong parts. What I can promise you is that building your own plasma cutting table will give you superior knowledge about how your tool works, which will enable you to quickly locate and fix problems.
Build Your Own Cnc Plasma Table
This CNC Plasma Table was made in collaboration with OpenBuilds, a company that sells open source linear actuators, CNC machines and many other tools that support the Maker community. We were able to retrofit their existing Lead Machine, typically used for CNC milling, for plasma cutting. This required a couple more modifications than just replacing the router with a plasma torch, so be sure to watch the video and read the supplemental information below to learn all the steps required for this conversion. Because this plasma table is based on the Lead Machine, it has been informally nicknamed the Lead Plasma.
Pourquoi Fabriquer Son Découpeur Plasma Cnc Soi Même ?
For maximum transparency, the parts needed to build the Lead Plasma were provided to Dr. D-Flo by OpenBuilds for beta testing. This project predates the official release of the Lead Plasma kit, so you’ll need to source the parts individually from the BOM below. I will update this project when the kit is released.
The BOM may contain affiliate links that provide monetary kickbacks to Dr. D-Flo. These funds are used to pay for this website and future projects.
CNC table construction is well documented because it is based on the Lead Machine. The assembly instructions for this machine are available here. OpenBuilds has also posted YouTube videos on the mechanical and electrical parts of this build.
Plasma cutting is a 2D process because there is no control over the depth of the cut (on hobby grade machines). Either you cut the material or you don’t. For this reason, a motorized Z axis is not required for the functionality of a plasma cutter. A manual slide that allows you to adjust the distance of the torch from the material would suffice, and many inexpensive plasma cutters forgo a Z-linear actuator. However, this manual torch height adjustment must be done at the start of each cut because not everything the material has the same thickness or flatness. Also, the material can warp during the cutting process, so it may be necessary to pause the plasma cutter between toolpaths to adjust the torch height.
Motorizing A Plasma Cutter On The Cheap
A floating head is a simple assembly that automates the initial torch height setting, but comes at the added cost of requiring a motorized Z-axis. In an ideal world, a switch would be on the bottom of the nozzle. As the Z actuator moves the torch closer to the material, the switch is eventually activated, signaling the computer that the nozzle is near or touching the material. Unfortunately, with this setup the switch would clear as soon as the plasma flow is started. This is a leap from the previous scenario, but what if the plasma torch was placed on a spring-loaded cart and the aforementioned switch was placed immediately above this assembly. In this configuration, if the Z actuator continues to push the torch down after the nozzle touches the material, the torch will move up as it is on the spring loaded carriage. This upward movement of this carriage would then activate the switch. As the Z sharpener moves up to retract the plasma torch, the spring (and gravity) will push the torch down to its original position. It’s best to study the accompanying animation to fully understand how the floating head works if you’re still confused.
Connecting the plasma torch to the moving head can be tricky, especially when trying to use a handheld torch. If possible, I always recommend using a machine flashlight (sometimes referred to as a pencil flashlight) because the straight body of this type of flashlight makes it easier to attach to the floating head. Most of the time you can strap the flashlight to the floating head. I prefer to use a 3D printer to make the holder. Whichever way you choose to mount the torch, it’s important to leave a way for it to pop out if you crash the Z-axis into the table, or you risk snapping the torch in half. For those with expensive machine flashlights, a magnetic tear-off flashlight mount is a great investment.
For many people it is not in their budget to buy a car flashlight. It’s more convenient to use the hand torch that comes standard with most inexpensive plasma cutters. The problem with this approach is figuring out how to grip this torch while keeping the nozzle perpendicular to the work material. The most common mounting point is right above the shield cup (the ceramic part that protects the internals from the heat of the plasma stream). The holder that grips the flashlight at this point must be heat resistant. As you saw in the video, I used a heat treatable PLA for the backing, which has worked well so far.
Plasma tables are typically so large that they require their own stand. They also need ample clearance from other shop tools because they throw off sparks and metal dust. When building a stand, it is important to select a sturdy design that can support not only the weight of the CNC frame, but also the material that will be cut. I’ve already cut a couple pieces of mild steel that were >100lbs (45kg). My garage doesn’t have a lifter so I have to slide the material across the plasma table and the holder has to withstand these shear forces.
Cnc Plasma Tables, Cnc Plasma Machines, Plasma Cutters
I found OpenBuild’s stand using 40×40 aluminum extrusion for the legs and 20×60 aluminum extrusion for the stringers to be very stiff and supportive. The stand project can be found in the SketchUp file in the downloadable section. I added casters, so I could roll the plasma cutter out of my garage whenever I dry cut material. I’ve created an STL file that allows you to attach a standard wheel to the bottom of the 40×40 aluminum extrusion, which is also in the downloads section.
The plasma cutting process generates fine particles that can be harmful to you and nearby electronics. If you operate a small shop, such as a garage, it is imperative that you take steps to prevent metal dust from contaminating the air in your shop. The two options for fume management are a falling table or a water table. Downdraft tables use a blower to draw fumes into ducts under the countertop before expelling them outside. Downdraft tables are expensive and usually only found in large fabrication shops. The other option for fume management is the groundwater. When the compressed air from the torch blows the molten metal down, it comes into contact with a pan filled with water. Instead of becoming an aerosol, the metal powder is trapped in the water. Groundwater is simple, cheap, and effective, which is why I used it for this build.
To hold the water I used a stainless steel drip pan, which is supposed to fit under a washing machine and catch the water, but worked great for the plasma cutter. The only problem with this pan is that I have to use a siphon to drain it. Welding a bottom drain is definitely a future project. The material I will be cutting rests on sacrificial staves, which are 1 3/4″ mild steel flat bars (1/8″ thick). To hold these slats upright I used right angle brackets attached to an aluminum extrusion platform. It is best to avoid using aluminum or stainless steel for the slats because both produce dangerous gases when plasma cut.
Whenever I really like a project, like this CNC plasma cutter, I do it right away