Fiber laser basics

Wobble: Why Cutting Metal Needs a Wiggling Beam

Cutting metal with a fiber laser relies on a technique called wobble. Our workshop explains why this "wiggling" beam is critical for clean cuts and how to set it up.

23 September 2026 · The HagoLaser team · 8 min read

Wobble: Why Cutting Metal Needs a Wiggling Beam

If you're trying to cut metal with a fiber laser and it just won't go through, even with endless passes, the answer might not be more power. It might be wobble. Laser wobble is a technique where the beam oscillates sideways as it follows the cut line, creating a wider path. Without it, molten metal often re-welds behind the beam, leaving you with a perfectly marked line that simply refuses to open.

What is Laser Wobble, Anyway?

Imagine trying to dig a narrow trench in sticky, wet clay with a single, thin spade. The clay you remove often falls right back into the trench, making it impossible to get deep. Now, imagine wiggling that spade from side to side as you push it forward. You'd create a wider, clearer path, and the dislodged clay would have room to escape.

Laser wobble works on a similar principle. When your fiber laser is cutting, the galvo mirrors don't just follow the vector line precisely. Instead, they quickly move the beam back and forth across that line, making the beam "wiggle." This creates a cut path – what we call the kerf – that is significantly wider than the laser spot itself. This wider kerf is absolutely crucial for cutting through metal.

Why a "Wiggling Beam" is Key for Metal Cutting

The core problem when cutting metals like sterling silver with a fiber laser is that the molten metal created by the laser beam needs to go somewhere. If the kerf is too narrow, the molten material has nowhere to escape. It cools and re-solidifies, effectively welding itself back together right behind the moving beam. You end up with a beautiful, deep engraving, but not a clean through-cut.

A wider kerf, created by wobble, provides the necessary space for the molten metal and vaporized material to be ejected from the cut. Without this escape route, the laser just works harder to re-melt metal that immediately solidifies, wasting energy and heating the workpiece unnecessarily.

This challenge is particularly pronounced with materials like sterling silver. Silver is the most reflective of common precious metals at the 1064 nm wavelength of a fiber laser, meaning much of your laser power simply bounces off. It's also an excellent heat conductor, quickly drawing heat away from the cut zone. This combination makes silver very difficult to cut, often requiring many passes – and always requiring wobble – to get through.

The Kerf: More Than Just a Line

The kerf is the width of the material removed by the laser. For engraving or surface marking, a narrow, precise line is often desirable. But for cutting, a wider kerf is your friend. It's the physical manifestation of the wobble doing its job: creating enough space for the melted material to be expelled, preventing re-welding, and allowing the beam to penetrate deeper with each pass.

Setting Up Wobble: The Numbers on Our Machine

In software like EzCad3, wobble settings are found in the parameter library, usually under the "Pen" settings. The key parameters you'll typically see are:

For our sterling silver cutting recipes, we use the following wobble settings:

These numbers are specific to our machine and our material, but they give you a starting point. The important takeaway is that these are not tiny values; they create a noticeable width to the cut.

The Decimal Point That Killed Our Cuts

We learned the hard way how critical the wobble diameter is. For months, our machine simply would not cut through 0.8 mm silver, despite correct power, speed, and dozens of passes. It looked like the job was running perfectly, but the metal just wouldn't separate.

The problem? A single misplaced decimal point. Our wobble diameter was set to 0.015 mm instead of 0.15 mm. That's a factor of ten difference. A 15 micron wobble is effectively a thin line, too narrow for the molten metal to escape. Once we corrected that decimal place, our machine cut through 0.8 mm silver in 17 passes, just as it should have.

This is the single most misleading failure on a fiber laser for cutting. The job runs, the laser fires, but nothing cuts. So, if your machine suddenly stops cutting through, check your wobble diameter first, before you touch anything else.

Focus Height: The Silent Partner to Wobble

While wobble is essential for clearing the kerf, it won't work effectively if your laser beam isn't properly focused. The more concentrated the beam's energy, the faster it melts the metal. An unfocused beam spreads its energy, making it less efficient at melting, and thus, less effective at creating the molten pool that wobble needs to eject.

On our machine, the factory-calibrated focus (where the platform surface is in focus) is -59.6 mm. When cutting sheet metal, the top surface of your material is actually above the platform. So, the rule is: Z = focus + material thickness. For a 1 mm sterling silver sheet, the correct Z-height on our machine is -58.6 mm.

We've verified this on our bench: a Z-height of -58.5 mm cuts perfectly, while -56.5 mm (a mere 2 mm difference) does not cut at all. A ±0.5 mm error is barely noticeable, but 2 mm kills the cut. If your cuts suddenly get worse and you haven't changed the file, check your focus height before anything else. A bent jig, thicker material, or a platform that shifted can all make your laser seem "weaker" when it's simply out of focus.

Our Silver Cutting Recipe with Wobble

With wobble enabled and the focus correctly set, these are the starting parameters we use for cutting sterling silver on our 100 W MOPA machine. Remember, these are our numbers on our specific setup, and you must prove them on scrap material first.

We've found that for cutting, higher frequency works better. While lower frequencies create fatter, more energetic pulses for deep engraving, they surprisingly make cutting worse. We tried dropping to 20 kHz on 0.3 mm silver, and it took 16 passes without cutting through. Back at 60 kHz, it cut in a handful of passes.

The number of passes is your primary lever for getting through the material. Turning up the power on a job that won't cut usually just widens the kerf and heats the piece, leading to distortion, especially on thin sections. For more on how these settings interact, you might find our article Speed, power, frequency and passes: which knob to turn first useful.

Measured Pass Counts for Sterling Silver

These are the pass counts we actually use on our machine for sterling silver sheet, at the settings above. These are measured values from real metal.

Sheet Thickness Silver Passes
0.3 mm ~2
0.5 mm ~6
0.8 mm 17
0.9 mm 21
1.0 mm 28-29

As noted in the facts, for gold, which reflects less and absorbs more of the beam, you would expect roughly half these passes at the same settings. However, any gold recipes must be treated as starting points and proved on scrap, as karat and alloy significantly change behavior.

Safety First: Always

A fiber marking laser is a Class 4 laser. The 1064 nm beam is invisible and causes permanent eye damage instantly and silently. Always wear laser safety glasses rated for 1064 nm (with an OD suitable for your source power) and ensure everyone in the room does too. Metal is a mirror; reflections go everywhere. Never leave a running job unattended, and always use proper fume extraction with a suitable filter. Physical interlocks and enclosures are your real safety layers; software is a convenience.

Practical Takeaways: What to Check First

If your fiber laser isn't cutting metal as expected, and you suspect wobble might be the issue, here's our workshop's checklist: