Common CNC Plasma Table Issues

Maintaining the smooth operation of your CNC plasma table is essential for producing high-quality cuts and minimizing downtime. Whether you’re dealing with a torch not firing, parts skewing, or controller connection issues, troubleshooting common issues quickly can keep your workflow on track. In this blog, we cover some of the most common CNC plasma table issues our customers face with plasma cutting systems and how to resolve them, from checking consumables to ensuring proper grounding and more.

Torch Not Firing

Torch Rising or Diving

Scribe Not Vibrating

Parts Skewed/Not Square:

Machine out of Envelope:

Cleaning Drawings:

Choosing the Correct Operation and FabHead:

Merging Layers:

Axis Faults:

Controller Not Connecting:

Import/Export Error:

Torch Not Firing:

  1. Check the front of your plasma unit to see if there’s a fault code.
    If there is, check the manual of the plasma unit you are using for the fault code solutions.
  2. Ensure your ground is connected properly.
    Attach the ground from the plasma unit to the material you’re cutting, a slat underneath it, or the ground block on the plasma table.
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  3. Double-check the consumables in the torch, making sure they are right consumables for the material you’re working with.
    Your program settings should match the consumables too.
  4. Low gas pressure can also stop the torch from firing.
    With a Hypertherm plasma unit, you want the pressure set at 100-110 psi. If it’s lower than that, you might lose the arc during cutting.
  5. Make sure your program isn’t in dry run mode.

Torch Rising or Diving:

  1. Your consumables need to match what’s in your program.
    For example, if you’ve got 45A consumables in the torch and you’re cutting 3/16″ plate, make sure your machine and plasma settings are set accordingly. The plasma needs to be set to 45A in this case.
  2. Proper grounding is key.
    Your ground should be on the material, a slat, or the table’s ground block. Ensure your ground is camlocked into the plasma unit, and that there’s no corrosion. If you see corrosion on the ground cable, trim it back to get fresh wire.
  3. Check consumables for wear.
    Worn nozzles or electrodes can cause unstable arcs, leading to the torch rising or diving unexpectedly.

Scribe Not Vibrating:

  1. Check the dial on the scribe.
    The dial should be set to 5 for proper vibration.
  2. If the scribe hasn’t been used for a while, it may need cleaning.
    Take the hose off the scribe and pour mineral spirits into the quick connect. Put the hose back on and run it manually for a few minutes. Then, take off the hose, add air tool oil to the quick connect, put the hose back in and manually run it again. If it’s still not working, open the scribe and blow it out.

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Parts Skewed/Not Square:

  1. Check the drawing first if your parts aren’t coming out square.
  2. Make sure the table is square and that you’ve homed the machine properly. If the limit switches have been hit or replaced, you might need to re-square the table.

Machine out of Envelope:

  1. If you see the error message “The toolpath goes outside of the machine envelope,” here’s what might be causing it:
  2. Wrong fab head selected.
  3. Parts nested outside your material with a toolpath on them.
  4. Program zero has moved.
  5. Machine homed incorrectly.
  6. The program zero is set in the incorrect corner of the sheet.

Cleaning Drawings:

Your drawing might have overlapping lines, open geometry, or too many nodes.

  1. In FlashCut CAD, use the Fix All tool to find and fix overlaps and open geometry.

This will circle where the issues are occurring and will fix them for you.

  1. The Arc Fitting tool in FlashCut CAD helps clean up your drawing by smoothing out the part and reducing the number of lines and arcs in it.

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Choosing the Correct Operation and FabHead:

Getting the right operation and fab head is crucial for the job.

  1. If you’re doing a profile or piercing cut, you can highlight the tool path, right-click, and set the operation you need.
  2. To set the fab head, highlight the part and set the fab head in the top-right corner of CAM.

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Merging Layers:

Sometimes, things might end up on different layers, messing with your lead-ins.

  1. To bring everything to the same layer, highlight everything you want included in CAD, click the down arrow on layers, and choose the layer you want to move it to.

Axis Faults:

Here’s a few ways to reset the motors when an axis fault hits:

  1. In CNC, click the motor reset button in the top-left corner of the screen.
  2. If the fault remains after clicking the reset button, power cycle the motor drivers (turn them off and then back on).
  3. If the problem sticks around, manually push the faulted axis (about 5-10 inches) with the power off.
  4. Lastly, if the fault remains, checking the bearings and wiring is next. First, turn off all the power to the motor drivers. All but the z axis can move manually. Then, move the axes to see if you feel or hear and blockage in the travel. Visually inspect the bearings for any damage. With the power off, inspect the motor wires to check for any disconnected or damaged connections.

Controller Not Connecting:

If the controller isn’t connecting, try these steps:

  1. Check the USB cable for cuts, nicks, or water damage.
  2. Check the controller and make sure it is on. With our Boss Tables, first, you need to turn on the LED rocker switch, and then switch on the metal toggle switches.
  3. Try another USB port or cable. The cable should be USB A to USB B.

Import/ Export Error:

When importing or exporting files, use the correct extension.

  1. Examples include: (.DXF), (.DWG), (.JPG)
  2. If you save a drawing in FlashCut, it saves as a CADCAM file, which only works in the FlashCut software. To export a (.DXF), click File > Export in CAD.
  3. If Importing into SheetCam, make sure you have the correct file selected.

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Fortunately, most of these common CNC plasma table issues are easy to fix once you know where to look. Additionally, by following these troubleshooting steps, you can effectively avoid downtime and keep your machine running smoothly. Furthermore, if you need more help, check out our YouTube channel where we walk through these solutions step-by-step. With the right setup and regular maintenance, you’ll keep your plasma machine working like a champ and get the best cuts every time.


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Updated: June 13, 2024

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