I Bought an xTool F1 Ultra — Here's What I Learned About Fiber vs. Diode (and 3 Materials That Almost Broke Me)

The xTool F1 Ultra Looks Like a Magic Box (It’s Not)

When the xTool F1 Ultra arrived, I honestly thought I’d figured it out. A 20W dual-laser machine—fiber and diode in one box—that can cut and engrave everything from metal to wood. What could possibly go wrong?

What I mean is, I spent about three months and roughly $1,200 in wasted materials learning that the F1 Ultra is incredibly powerful, but only if you understand which laser head to use for which material. If you don’t, you’ll create a lot of expensive trash—like I did.

So let me walk you through the three most surprising scenarios I ran into, and how to avoid them. I’ve personally documented 47 separate engraving failures (yes, 47) in the last eight months, so you don’t have to.

Scenario 1: Engraving Painted Canvas — The “Safe” Material That Isn’t

You’d think canvas is easy. It’s soft, it’s paintable, it’s not metal. But engraving painted canvas with the xTool F1 Ultra is a perfect example of why reading the conventional wisdom isn’t enough.

Everything I’d read said the diode laser is perfect for organic materials like canvas. In practice, for painted canvas with multiple acrylic layers, the 20W diode laser burned the paint into a brittle, crusty mess. I ruined three canvases in one afternoon—about $90 in materials plus the pain of restarting a client’s custom artwork.

Here’s what I eventually figured out: painted surfaces absorb laser energy differently than raw canvas. The diode laser (445nm) works great for unpainted canvas or single-layer paints. But for multi-layer acrylics, the fiber laser (1064nm) gave me a far cleaner result—crisper lines and almost no charring. Counterintuitive, I know.

Quick Checklist for Painted Canvas

• Thick, multi-layer paint → use the fiber laser at medium power (40-60%)
• Single-layer, water-based paint → diode laser is fine (start at 30% power)
• Always test on a hidden corner first—the paint chemistry varies wildly

Scenario 2: Engraving Glassware — Is the xTool F1 Fiber Laser the Answer?

This is the question I see everywhere: “Is the xTool F1 20W fiber laser good for glassware?” The short answer: yes, but not in the way you might think.

The fiber laser can mark glass, but you won’t get a deep engraving. What you get is a frosty, micro-fractured surface—which looks beautiful for wine glasses and tumblers, but it’s not a true cut. If you’re thinking of selling engraved glassware gifts, this is actually perfect because it gives a high-end, etched look without the cost of sandblasting.

But I made the mistake of trying to use the diode laser on glass. It didn’t work. At all. The beam passes right through clear glass. I melted a thin wine glass in less than three seconds. That mistake cost me a $45 glass and a bit of my pride.

“If you’re serious about glassware, the fiber laser on the xTool F1 is the only head you should use. The diode is useless here—save it for wood and acrylic.”

Glassware Settings I’ve Found Reliable

• Fiber laser, 30% power, 300 mm/s speed — gives a nice frosted mark
• For darker marks, use a marking spray (cerMark or similar) and lower speed to 200 mm/s
• Never use diode laser on clear glass—it’s basically a waste of time

Scenario 3: CNC-Like Cuts in Wood and Acrylic — The Diode Laser Shines Here

If you’re looking for a CNC laser cutter for sale that can handle small parts, the xTool F1 Ultra, especially with the diode laser, is—in my experience—surprisingly capable for thin materials. I’ve cut 3mm birch plywood and 2mm acrylic cleanly with the diode laser, no problem. But here’s the rub: it’s not a 50W CO2 laser. You can’t cut 10mm acrylic in one pass. You’ll get a charred, half-done mess.

The decision between the fiber and diode for cutting is actually pretty simple:

• Fiber laser — best for marking metals and some plastics. Not great for cutting wood or acrylic.
• Diode laser — great for cutting thin wood, acrylic, and leather. Awful for metals (unless you use marking spray, and even then it’s slow).

I went back and forth between the two lasers for my first month. The fiber is a precision tool; the diode is a workhorse. They’re not interchangeable. That’s not a weakness—it’s a feature. But you have to know which scenario you’re in.

How to Know Which Scenario Applies to You

This is the most important part, and it’s where I see people get stuck. The xTool F1 Ultra is a dual-laser machine, meaning it has both heads. So you’re not choosing between two machines—you’re choosing which head to use for each job.

• If you mainly work with painted surfaces, canvas, or coated materials — start with the fiber laser. It handles coatings much better.
• If you’re engraving glassware for gifts — fiber laser is your only real option.
• If you’re cutting wood or acrylic — diode laser is your friend. Fiber won’t cut these well.
• If you’re unsure — do a test run on a scrap piece. This might be the single most valuable thing I learned after the third rejection in Q1 2024.

I honestly believe the F1 Ultra is the best small-format laser engraver I’ve used for under $1,500. But only if you’re willing to learn the difference between fiber and diode. If you just turn it on and expect it to guess your material, you will waste money—and I’ve done that enough for both of us.

There’s no universal “best” setting. There’s only the right tool for the material in front of you. And with the F1 Ultra, you’ve got two tools in one box. Don’t make the mistake of ignoring one of them.