Gantry or galvo: which laser design suits your projects
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A laser engraver has to guide the laser spot across the material. There are two fundamentally different solutions: with a gantry the whole laser head moves, with a galvo mirrors steer only the beam. That sounds like a technical detail, but it decides speed, work area and whether you can cut.
The gantry principle
With a gantry, the laser head sits on a carriage. It moves on two axes across the work area, driven by stepper motors and belts or lead screws. Some machines use a CoreXY layout, in which two motors move both axes together. The beam always hits the material vertically from above.
Almost all diode lasers and practically all hobby CO₂ lasers work this way. Examples are the xTool S1 40W as an enclosed diode laser and the xTool P2S as a CO₂ laser.
The galvo principle
With a galvo, the laser head stays still. Inside the head are two small mirrors on galvanometer drives. One deflects the beam in the X direction, the other in the Y direction. A flat-field lens (F-theta lens) ensures that the spot stays in focus on one plane across the whole work field.
Because only light mirrors move and no mechanism with weight, a galvo is extremely fast. Fibre and UV lasers are almost always galvo machines. There are also diode lasers with a galvo, such as the xTool F2, which combines a diode with an infrared laser.
The comparison
| Gantry | Galvo | |
|---|---|---|
| Movement | laser head moves on axes | mirrors steer the beam, head stays still |
| Typical speed | 400 to 600 mm/s for hobby diode lasers, CO₂ machines sometimes 1,000 to 2,000 mm/s | 4,000 to 15,000 mm/s |
| Work area | usually 300 x 300 to 850 x 800 mm, compact machines from 110 x 110 mm | small, usually 100 x 100 to 220 x 220 mm |
| Beam | always vertical | slightly angled at the edge of the field |
| Cutting | good, including thick material | thin material only, cut edges become slanted |
| Engraving large areas | slow, but with no size limit | very fast, but only within the field |
| Typical lasers | diode, CO₂ | fibre, UV, sometimes diode and infrared |
The speeds come from manufacturer specifications of the machines in our device overview. They are maximum values for the movement. How fast you actually work is determined by material and power.
Speed: the big advantage of the galvo
A galvo engraves a small logo on a key ring in a few seconds. A gantry laser needs many times longer, because the head has to slow down at the end of every line, reverse and accelerate again. With large areas and photo engravings this adds up.
For series production of small parts, this makes a real difference: engraved pendants, pens, lighters, jewellery or nameplates run through much faster on a galvo.
Work area: the big advantage of the gantry
The work field of a galvo depends on the lens. The larger the field, the larger the laser spot becomes, and the more obliquely the beam hits at the edge. That is why galvo fields stay small. The ComMarker B4 20W, for example, has 110 x 110 mm.
Some galvo machines extend this with accessories: a sliding unit or a conveyor belt moves the workpiece on under the field, and the software stitches the parts together. This works, but it is more involved than a large gantry bed.
Gantry lasers, by contrast, are hardly limited. Open diode lasers sometimes have areas of 400 x 400 mm and more. With risers or pass-through slots you can also work on workpieces that extend beyond the machine.
Cutting: only makes sense with a gantry
For cutting, the beam has to act vertically and long enough at one spot, often over several passes. A gantry does this well. A galvo hits the material slightly obliquely at the edge of the field, and with thicker material the cut edges become crooked. According to the manufacturers, galvo diode lasers do cut thin wood and dark acrylic, but cutting is not their strength.
Fibre galvos cut thin sheet metal, usually under 1 mm. For wood and acrylic blanks in A4 format and larger you need a gantry.
Focus and workpiece height
Both designs have a fixed focal distance. On a gantry, the head or the support is adjusted in height, and many machines have autofocus for this. On a galvo, you set the working distance between lens and workpiece, often with a height-adjustable column. More on this in the article Laser focus.
Which design suits you?
A gantry suits you if you
- want to cut wood, plywood, acrylic or felt,
- make large signs, boards or blanks,
- want to cover as much as possible with one machine.
A galvo suits you if you
- mainly engrave or mark small parts,
- want to work on metal (usually with fibre),
- need many identical parts in a short time.
Many workshops end up with both: a gantry laser for blanks and wood, a galvo for metal and small series. To start with, a gantry diode laser is the more flexible choice. A galvo is more of a second machine, once you know exactly what you want to make in series.
Safety applies to both
An open galvo is class 4 just like an open gantry laser. Because the beam jumps quickly across the field and reflections can go in many directions, you need safety glasses that match the wavelength. With fibre and UV you cannot see the beam. Both produce smoke, so plan for extraction and do not leave the machine running unattended.
Continue with: Laser types compared and Engraving, cutting, marking