ComMarker B4 vs ComMarker B6 MOPA: Which Should You Buy?

These two machines look similar at first glance — they're both compact desktop fiber lasers from ComMarker, both support LightBurn and EZCAD2, and both punch well above their price class for metal engraving quality. But the differences between them matter, and if you buy the wrong one for your workflow, you'll either overspend on features you don't use or hit a ceiling faster than you expected.

This guide cuts through the spec sheets and gets to what actually matters in daily use — how each machine handles metal, what the autofocus difference means in practice, whether color engraving is worth paying for, and which one makes more financial sense for your specific situation.

Same Brand, Very Different Value Propositions

The B4 is ComMarker's entry-level professional fiber laser — a Q-switched machine available in 20W, 30W, and 50W configurations, designed to be approachable, affordable, and reliable. It's the machine most people start with when they're stepping into fiber laser engraving for the first time.

The B6 MOPA is a different animal. It's built around a JPT M7 MOPA (Master Oscillator Power Amplifier) laser source — the same laser engine found in serious professional fiber marking systems — and available in 20W, 30W, and 60W versions. The defining feature is MOPA's adjustable pulse width (1–500ns), which unlocks color engraving on stainless steel and titanium and finer control over marking depth and heat. It also adds electric autofocus, which the B4 lacks.

Importantly, ComMarker's own B4 MOPA variant — which bridged some of the gap between these two — has been discontinued. If you want MOPA technology from ComMarker's compact lineup, the B6 MOPA is now the machine to consider.

The price difference reflects these upgrades: the B4 20W starts under $500, while the B6 MOPA 20W starts around $800 and the 60W version runs to $1,500–$2,000. The question is whether those upgrades are worth it for your work.

ComMarker B4: What You Get

For a complete breakdown of the B4's real-world performance, see our ComMarker B4 review.

Laser Source and Power

The B4 uses a standard Q-switched fiber laser. In a Q-switched system, the laser fires at a fixed pulse duration — typically around 120ns — and a frequency range of 20kHz to 100kHz. You control power and speed, but you can't adjust how the energy is delivered at the pulse level.

For standard metal marking — high-contrast logos, serial numbers, text, and deep engraving on stainless steel, aluminum, brass, and other metals — this is completely sufficient. The B4 produces fast, clean, professional results at all of its available wattages. At 20W it handles everyday marking tasks with ease. At 30W and 50W, the engraving depth and throughput speed increase meaningfully. TechRadar's hands-on review of the B4 20W noted that it reaches 0.01mm precision and a maximum engraving speed of 15,000 mm/s — figures that are competitive with machines costing significantly more.

The B4 cannot produce true color engraving on stainless steel or titanium, and it can't achieve the fine surface annealing effects that MOPA pulse control enables. If those things aren't part of your current or planned product line, this is not a limitation that affects you.

Manual Focus and Dual Lenses

The B4 uses a manual focusing system: an electric lifting motor raises and lowers the laser head, and you align focus by watching for three red laser dots to converge into a single point on your material. It's straightforward once you've done it a few times, but it does require a manual step before each job on new material thicknesses.

The B4 ships with two field lenses as standard — a 110mm lens (110 × 110mm working area) and a 200mm lens (200 × 200mm working area). The smaller lens gives tighter focus and deeper, more detailed engravings. The larger lens is better for surface marking, color work, and larger pieces. This dual-lens setup is one of the B4's genuine advantages — it gives you meaningful flexibility without needing to buy additional accessories.

Who the B4 Is Best For

The B4 is the right starting machine for anyone new to fiber laser engraving who primarily works with metals and wants professional-grade results at an accessible price. It handles stainless steel, aluminum, brass, titanium, copper, gold, silver, engineering plastics, and leather well. It's fast, reliable, LightBurn compatible, and rated for over 100,000 hours of laser source life.

If your main products are metal tags, knife blades, anodized aluminum items, jewelry, or branded metal components — and you don't need color marking — the B4 is a capable professional tool at a genuinely competitive price. You can Buy the ComMarker B4 directly from The Maker's Chest.

ComMarker B6 MOPA: What the Upgrade Adds

For a full hands-on performance breakdown, our ComMarker B6 MOPA review covers real-world testing across materials.

MOPA Pulse Control: The Core Difference

The B6 MOPA uses a JPT M7 MOPA laser source, available in 20W, 30W, and 60W. MOPA architecture decouples the oscillator from the power amplifier, allowing independent control of pulse duration (1–500ns) and frequency (1kHz–4,000kHz). Compare that to the B4's fixed ~120ns pulse and 20–100kHz range, and the difference in parameter space is immediately clear.

In practice, this means the B6 MOPA can produce color marking on stainless steel and titanium through controlled thin-film oxidation, achieve clean true-black annealing on stainless steel without marking spray, mark engineering plastics without burning or discoloration, and deliver finer control over engraving depth from a single pass. The B6's maximum pulse energy of 1.5mJ ensures deep engraving on a wide variety of metals, including stainless steel, brass, and gold.

For makers who want to offer color-branded jewelry, vibrant tumbler designs, or premium metalwork where the finish quality is part of the product's value, MOPA pulse control is the technology that makes it possible. Standard fiber lasers produce black-and-gray marks; MOPA lasers produce black, gray, gold, blue, purple, and more — permanently embedded in the metal surface, with no inks or coatings.

Autofocus and Compact Design

The B6 MOPA's most practically significant upgrade over the B4 is electric autofocus. A Panasonic industrial measurement sensor determines the correct focal distance and moves the laser head automatically — accurate to 0.01mm. You press a button on the touchscreen, the machine focuses itself, and you're ready to engrave. No three-dot alignment, no manual adjustment, no checking.

Hobby Laser Cutters' review was direct about this: the B6 is one of the smallest, most compact fiber laser engravers on the market, and thanks to autofocus capability, also one of the easiest to use. At 13.5kg with a modular 2-in-1 design (desktop or split configuration), it's also genuinely portable — light enough to take to events, client locations, or between workstations without a trolley.

The standard working area is 150 × 150mm via the included field lens, with an optional 300 × 300mm lens available (recommended at 60W for best quality at that size).

Color Engraving Capability

Color engraving on metal is the capability that gets the most attention around MOPA lasers, and the B6 MOPA delivers it. By adjusting pulse width and frequency, the laser controls the thickness of the oxide layer that forms on stainless steel or titanium during marking. Different oxide layer thicknesses reflect light at different wavelengths — producing gold, blue, purple, teal, and other hues that are permanent, chemical-free, and embedded in the metal itself.

The results require parameter experimentation to dial in. Blues and golds are the most consistent and repeatable. Getting to pure red is harder — most settings tend toward copper or brown at that end of the spectrum. Colors are also somewhat viewing-angle dependent, appearing richer from some angles than others. Color engraving runs at much slower speeds than standard marking — around 900mm/s versus the 15,000mm/s maximum — so production time per item is longer for color jobs.

That said, the results are commercially compelling. Custom color jewelry, branded tumblers with color logos, and artistic metalwork with color fills are premium product categories that standard fiber lasers simply cannot serve. If those are products you want to sell, the B6 MOPA is what makes them possible.

Direct Comparison Across Key Criteria

Metal Engraving Performance

For standard metal marking — logos, text, serial numbers, QR codes, and decorative designs in black and gray — both machines perform at a professional level. The B4's Q-switched fiber produces sharp, high-contrast marks on all common metals at excellent speed. The B6 MOPA produces equally sharp marks and, at the 60W level, achieves greater material removal depth per pass.

The key difference in day-to-day metal engraving isn't quality — it's control. The B6 MOPA's pulse width flexibility lets you fine-tune the marking effect per material: a polished surface mark on stainless steel, a matte annealed black, or a colored oxide layer are all achievable from the same machine by adjusting parameters. The B4 produces a consistent, excellent mark, but within a narrower range of outcomes.

Color and Special Effects

This is a clean win for the B6 MOPA. The B4 does not produce color on metal — its fixed pulse architecture doesn't allow the oxide layer control that color marking requires. The B6 MOPA does, and at the 60W level produces more vivid, saturated colors than the 20W version.

Beyond color, the MOPA source also enables clean black marking on anodized aluminum without burning through the anodized coating, and burn-free marking on engineering plastics that standard fiber lasers can scorch. If any of those applications are part of your workflow, the B6 MOPA is the only option between these two.

Ease of Setup and Use

The B4 is genuinely beginner-friendly. The three-dot manual focusing system is simple once learned, the dual-lens configuration is intuitive, and the LightBurn Galvo plugin gets you running quickly. TechRadar noted that it's easy to start engraving shortly after unboxing — the physical buttons for height adjustment and power are simple and reliable.

The B6 MOPA raises the floor even higher with electric autofocus. Once you've manually focused a B4 a few hundred times, the one-button autofocus of the B6 MOPA feels like a significant quality-of-life improvement. Setup time per job is shorter, and the touchscreen interface on the B6 MOPA makes machine control more intuitive than relying entirely on software commands.

Both machines support LightBurn and EZCAD2, which means your existing skills and parameter libraries transfer between them. Settings made for the B4 MOPA (before its discontinuation) transfer directly to the B6 MOPA with minimal adjustment, since both use the same JPT M7 laser source.

Price: Is the Jump Justified?

The B4 20W starts under $500. The B6 MOPA 20W starts around $800. The B6 MOPA 60W — the version most serious producers will want — sits at $1,500–$2,000. That's a meaningful step up for the 60W, and it's worth asking honestly what it buys.

For color engraving and autofocus alone, the price jump is reasonable if those capabilities are central to your product line. For a small business that sells custom color metal jewelry or branded tumblers at any volume, the premium generates return relatively quickly. For a shop that only needs high-quality black marking on metal, the B4 provides everything required at a fraction of the cost.

The B4's larger maximum working area (200 × 200mm vs 150 × 150mm standard on the B6 MOPA) is also worth noting — if you regularly work on larger metal pieces, the B4's 200mm lens may be more practically useful than the B6 MOPA's standard 150mm field.

Who Should Buy the B4?

The B4 is the right machine if you're entering the world of fiber laser engraving for the first time and want professional-grade metal marking without the premium of MOPA technology. It's also the right choice if your work is primarily focused on deep engraving, high-speed batch marking, or standard high-contrast black marks on metal — applications where the B4's Q-switched fiber laser performs excellently.

It's a strong fit for small businesses engraving metal tags, dog tags, knife blades, firearms accessories, awards, or personalized gifts where monochrome output is the standard. The dual-lens configuration adds meaningful flexibility for larger pieces without extra cost. And at its entry price, it's one of the lowest-cost paths to professional fiber laser capability available from a reputable brand.

Who Should Buy the B6 MOPA?

The B6 MOPA is the right machine if color engraving on stainless steel or titanium is either a current product offering or a planned one. It's also the right choice if electric autofocus is important to your workflow — particularly if you do high volumes of small, varied items where manual refocusing per batch adds up in time.

Jewelry makers producing color-accented pieces, custom tumbler and drinkware businesses adding color logos, and knife makers wanting colorful temper-pattern effects are natural fits for the B6 MOPA. The compact, portable 2-in-1 design also makes it a practical choice for anyone doing on-site work, pop-up events, or trade shows.

For anyone who owned or was considering the now-discontinued B4 MOPA, the B6 MOPA is the direct replacement — same JPT M7 laser source, same engraving performance, more compact, and with autofocus added. If you're in that position, Buy the ComMarker B6 MOPA from The Maker's Chest.

Verdict

The B4 and B6 MOPA aren't really competing for the same buyer. The B4 is a brilliant entry-level professional fiber laser — capable, affordable, beginner-friendly, and well-suited to the most common metal marking use cases. The B6 MOPA is a step up in capability and convenience, justified if color engraving or autofocus are part of what you're building toward.

If you're not sure which one fits, start here: do you want to offer color-marked metal products? If yes, the B6 MOPA is worth the extra investment. If no, the B4 handles everything else you need at a price that's hard to argue with.

Frequently Asked Questions

What is the main difference between the ComMarker B4 and B6 MOPA?

The core difference is the laser source. The B4 uses a standard Q-switched fiber laser with a fixed pulse duration (~120ns) and a limited frequency range. The B6 MOPA uses a JPT M7 MOPA fiber laser with adjustable pulse width (1–500ns) and a much wider frequency range (1kHz–4,000kHz). This difference enables the B6 MOPA to do things the B4 cannot: color marking on stainless steel and titanium, clean black annealing on stainless without marking spray, and burn-free engraving on certain plastics. The B6 MOPA also adds electric autofocus, which the B4 lacks. Both machines support LightBurn and EZCAD2 software.

Can the ComMarker B4 do color engraving?

No. The B4's Q-switched fiber laser has a fixed pulse duration, which means it cannot control the oxide layer thickness on metal surfaces needed to produce different colors. Color marking on metals like stainless steel and titanium requires MOPA pulse-width control. The B4 produces excellent high-contrast black and gray marks, but not color. If color engraving is part of your product line or planned product line, the B6 MOPA is the machine you need.

Why was the ComMarker B4 MOPA discontinued?

ComMarker discontinued the B4 MOPA and positioned the B6 MOPA as its successor for users who want MOPA capability. The B6 MOPA uses the same JPT M7 laser source as the B4 MOPA, delivers identical laser performance, but packages it in a more compact, lighter body with electric autofocus added. If you were considering the B4 MOPA before it was discontinued, the B6 MOPA is the direct equivalent with meaningful ergonomic improvements.

Which machine has the larger working area — B4 or B6 MOPA?

The B4 has a larger maximum working area. It ships with both a 110 × 110mm lens and a 200 × 200mm lens as standard, giving you flexibility for both detailed small engravings and larger pieces. The B6 MOPA's standard field lens gives a 150 × 150mm working area, with an optional 300 × 300mm lens available as a separate purchase (the 60W version is recommended for the larger lens). For shops working on larger metal pieces regularly, the B4's included 200mm lens is a practical advantage.

Do the ComMarker B4 and B6 MOPA work with LightBurn?

Yes, both machines support LightBurn via the LightBurn Galvo plugin, as well as EZCAD2 which ships with each machine. LightBurn is generally preferred by creative makers for its intuitive interface, while EZCAD2 offers deeper parameter control suited to industrial marking workflows. Parameter settings made on one machine transfer to the other with minimal adjustment, particularly when both are running the same JPT M7 laser source (as with the 60W versions).

Is the B6 MOPA significantly harder to learn than the B4?

For standard metal marking, no — the B6 MOPA is actually easier to operate day-to-day because of the electric autofocus. Getting started is faster and there's less manual setup per job. The steeper learning curve applies specifically to color engraving: dialing in consistent, repeatable colors on stainless steel requires building a parameter test grid and experimenting with frequency and pulse width settings. This takes real investment of time. For everything other than color work, the B6 MOPA is at least as beginner-friendly as the B4.

What is the price difference between the B4 and B6 MOPA?

The B4 starts under $500 for the 20W version, making it one of the most affordable entry points into professional fiber laser engraving. The B6 MOPA starts around $800 for the 20W version and ranges up to $1,500–$2,000 for the 60W version. The 60W B6 MOPA is the version most serious production users choose, as higher power produces more vivid color results and faster deep engraving. For color engraving specifically, the 60W version is a meaningful upgrade over the 20W. Always check current pricing as promotional deals are common on both machines.