CHEAPEST (Low Cost) CNC PLASMA CUTTER Machine | How To Build A DIY CNC Plasma Cutter
THE FRAME
The proliferation of inexpensive laser cutter engravers has dropped the cost of simple CNC machines that can support the load of a torch head. Normally CNC plasma cutter frames are built strong, often as strong as a CNC router. For non-industrial use, the frame doesn't need to be nearly as strong, so these basic laser engravers will work.
$150 - 350mm x 350mm - https://s.click.aliexpress.com/e/_mP2J8hM
$245 - 1m x 1m frame (no laser) - https://www.ebay.com/itm/134222584547
THE PLASMA CUTTER
A CNC plasma cutter requires a non-high-frequency start plasma cutter. In the past, these were expensive and sold by companies like Hypertherm.
YESWELDER now sells some inexpensive non-high-frequency start (blowback start) plasma cutters that supposedly cut thin sheet metal just as well as the Hypertherm fine-cut consumables. This plasma cutter costs less than $200 (after the Amazon coupon is applied).
WHERE TO BUY
THE TORCH HEAD
Another advantage of the YESWELDER CUT-55DS Pro is the torch is easy to modify into a machine torch. The entire machine costs less than half the price of a Hypertherm machine torch alone.
Watch this video to see how to easily modify it and use a 3D-printed part to house the modified torch design.
Here's the inspiration video from John Hanskenecht, the maker of the 3D-printed housing.
This is the 3D-printed housing that turns the YesWelder CUT-55DS PRO, or CUT-65DS hand torch into a machine torch.
How To Modify The Torch
Remove the screws holding the housing together.
Open the housing.
Take out the torch head and cable.
Disconnect the trigger wire from the switch.
Cut the trigger wire going to the consumables sensor contact.
Cut the zip tie building the cables together.
Pull the trigger wire through the cable sheath. (Connect it to the CNC controller).
Twist the air tube 180 degrees counterclockwise (loosen) such that the cables are now in line.
Reassemble the torch head into the 3D-printed machine torch body.
Mount the new DIY machine torch.
How To Trigger Torch From Laser Cutter Controller
The diode laser used on the inexpensive laser cutters usually has a 3-pin input. This needs to be adapted to trigger the plasma cutter torch instead.
These are the standard connections:
Ground
Power (+5V to 12V)
PWM Signal Laser
There are these relay boards available that take a PWM input (usually from RC controller) and switch the outputs of a relay. Buy the relay board on Amazon.
The torch trigger wires will be connected to the normally open contacts on the terminal block.
The PWM signal is connected to the white or yellow wire of the input.
The positive power from the CNC controller is connected to the red wire of the input.
The ground from the CNC controller is connected to the black wire of the input.
TORCH TRIGGER CABLE TO CNC CONTROLLER
Once the torch is modified the torch trigger cable can be removed from the cable assembly sheath or a new cable with a 2 pin GX16 connector can be connected into the trigger port on the plasma cutter.
This torch trigger replacement is a perfect cable to use to connect to the CNC controller. Cut the switch off the end and connect the bare wires to the CNC controller output.
Trigger Extension Cable
ARC ON SIGNAL
The arc on signal is used by the CNC controller to sense whether the arc is still on or not. If the arc cuts off, the CNC controller needs to know this and pause the cutting operation. The CNC plasma cutter machine will still work without an arc on signal output from the plasma cutter, but the machine won't know to stop if the arc is off. If you are constantly monitoring the cutting operation, and can shut off the machine if there is a missfire, then you don't need it. But if you want more reliable cutting, you're going to need the arc on signal.
Most inexpensive plasma cutters won't have an arc on signal output. It can be added inexpensively in a few different ways.
REED SWITCH
The most inexpensive, and possibly easiest way to add an arc on signal is to use a reed switch.
If the reed switch doesn't already have wire leads, solder two wires to reedg
Use a small plastic tube a bit longer than reed body. Choose a tube that the ground lead can be wrapped around. This could be the external ground lead or the internal wire going to the ground lead connection.
Secure the reed switch inside the plastic tube.
Wind 3 turns of the ground lead around the tube
Use zip ties to secure the windings in place.
Wire the reed switch to the arc on signal input on the CNC controller.
This is an example of what that looks like (image is from this post).
I read about the reed switch method in these posts:
Glass style reed switches are the most basic form and require soldering to wires and potting it in something to protect it. Buy glass reed switches.
The following reed switches are prepackaged with wire leads, and are therefore easier to install.
These cylindrical plastic encased reed switches with wire leads are also a good option.
DC CURRENT SWITCH
A DC current switch is an induction coil that goes around the ground or torch lead, and has an output that indicates whether there is current or not . The current sensing level is adjustable.
The DC current switch needs to be powered from a DC power source. If one can be found within the plasma cutter, that can be used. Otherwise need to use an ac-dc power adapter.
The diagram below shows 12/24 volts, but the voltage shouldn't matter.
WHERE TO BUY
THE CUTTING TABLE
I'll be using my DIY plasma cutter table for this build. It's super easy to make. Watch how I made it:
Water Table Pan
An inexpensive source for stainless pans suitable to be used as water tables are ones sold for washing machines. They are available in several different sizes.
How To Build CHEAPEST CNC PLASMA CUTTER Machine
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The products shown here were purchased by me with the intent to use them. I did not receive any free items, and I am not being paid or compensated for this review. The video, description, and comments may contain affiliate links. If you click on a link, I may receive a commission. Money earned helps to support my channel and bring you more informative videos about engineering, crafting, and DIY
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