Part 5: Plasma Cutter Selection

Picking the right plasma cutter is one of the biggest decisions in building a CNC plasma table. It’s not just about cutting metal — it’s about reliability, cut quality, and how easy (or frustrating) your machine will be to live with.

Let’s break down the key choices you’ll need to make.

Blowback vs HF Start

There are two main types of plasma cutters, and they use different methods to ignite the arc, high frequency start and blowback start:

• HF (High Frequency) Start:

  Creates a high-voltage spark to start the plasma arc.

  Good: Works well, cheaper machines often use it.

  Bad: They emit high frequency signals which can interfere with your electronics — causing strange glitches and reliability issues with CNC controls. It’s one of the biggest causes of strange behaviour in DIY builds. If you go down this route, be prepared to spend some time learning how to protect against these signals.

• Blowback Start (preferred):

  A mechanical method where the torch electrode physically moves to start the arc.

  Good: Much cleaner electronically — no high-frequency noise, far better for CNC use.

  Bad: Usually found on more expensive or newer machines.

Bottom line: For CNC builds, blowback start is strongly recommended if your budget allows.

Machine Torch vs Hand Torch

• Hand Torch:

  Designed for manual use — comes with a trigger and a handle.

  Pros: Cheaper, comes standard with most plasma cutters.

  Cons: Awkward to mount on a CNC, hard to line up precisely. Usually requires opening the hand torch and splicing in some wires to control the On/Off of the torch.

• Machine Torch:

  Built specifically for CNC machines — straight body, no trigger, designed for mounting.

  Pros: Easier to mount, more consistent consumable alignment, generally better for repeatability. Often will come with a port on the back that connects into your motion controller.

  Cons: Extra cost (~£300–£600 depending on model).

Good news: You can start with a hand torch if budget’s tight — just be prepared to get creative with mounting and the splicing. Machine torch recommended.

Amperage: How to Size for Material Thickness

Amperage determines how thick you can cut cleanly.

Here’s a rough guide, every cutter is different, this is just a general guideline:

• Rule of Thumb: Aim for a cutter that can cleanly cut 80–90% of what you plan to cut — don’t size it just for maximum thickness.

Tip: Cutting at the low end of your cutter’s range usually gives the best edge quality.

Brand Considerations

This is where things get interesting. You’ll hear a lot of strong opinions online — here’s my honest take:

• Hypertherm:

  Industry standard for a reason — incredibly reliable, excellent cut quality, designed with CNC use in mind. Fantastic customer support. Detailed cut charts.

  Cons: Expensive upfront cost.

• Budget Chinese Cutters (e.g., Cut60L, Primeweld):

  Much cheaper, surprisingly capable for hobby or light production use.

  Cons: Tend to be high frequency start. Quality control can vary, warranty support is often limited or nonexistent. Blowback models are getting more common though — a plus.

• Mid-range brands (Jasic, Everlast, Thermal Dynamics):

  Sit between budget and Hypertherm — decent performance, more affordable, but double-check CNC compatibility before buying.

Verdict: CNC-Ready Features to Look For

If you’re shopping specifically for CNC use, look out for these:

• Blowback start torch (No HF signals messing with your electronics setup)
• Vertical machine torch (much easier mounting and simplified setup)
• CNC / CPC port (or easy connection to your controller)
• Divided arc output (for easy Torch Height Control connection to your controller).
• Pilot arc (helps start cuts without direct torch-to-metal contact).
• Consumables availability (avoid obscure brands — you’ll regret it later).
• Cut charts — a proper manual with tested settings is a huge bonus.

Personal Recommendation:

Hypertherm Powermax Sync with 180 degree machine torch.