Guide · Updated: August 28, 2026
A rotary turns your laser's Y axis from travel into rotation: instead of the head moving up the bed, the workpiece turns underneath it, and the engraving wraps around a tumbler, a bottle, a rolling pin or a pen. On a GRBL machine that is a handful of settings — and the order you do things in matters more than any of them.
What follows is the sequence that works, in the order it has to happen. The two steps people get wrong are when to plug the rotary in, and where to put the design.
You need two figures, and both come with the rotary — its manual, or the manufacturer's setup video. They are usually called mm per rotation and roller diameter.
You do not need to know anything about motor steps, microstepping or gear ratios. Lùmen works the Y scale out from those two numbers and your machine's own flat calibration, which it reads off the controller the moment you connect. If your rotary is a chuck rather than a pair of rollers, the second number is the workpiece itself — a chuck's scale changes with every object you clamp in it.
Sit the rotary on the bed with its rollers parallel to the frame, and put the object on it. Leave the cable alone for now; step 5 explains why.
Switch the machine on and connect. If your laser has a homing cycle, home it now. Then jog Y until the head sits over the exact line of the object you want to engrave, and X to where the design should sit along it. The laser pointer — low power, no burn — is the easiest way to see where you are.
This is the step you cannot go back to. The rotary takes the Y motor's place, so from the moment it is connected the gantry cannot move in Y at all. Whatever Y the head is parked at is where it stays for the whole job.
With the head where you want it, press Set Zero. That point is now the origin of your design, and the crosshair on the canvas is it.
On a cylinder that point should be the crest — the top line of the object, where the beam arrives perpendicular and in focus. The further the engraving wraps away from it, the further the surface falls away from the focal plane.
Open Rotary setup and fill in the two figures from step one, plus the diameter of the object you are engraving (or its circumference — type whichever you have, and the other fills itself in). Lùmen shows you what it will write to the machine and how tall one full turn of your object is.
Press Switch to rotary, and only after that plug the rotary in.
That order is not fussiness. Software cannot see a cable: until the mode is on, your machine will still happily accept a homing cycle — and homing with a rotary fitted sends the head to its X limit switch while the Y axis spins your workpiece looking for a switch that is now a bottle. Switching the mode first is what turns homing off.
The canvas is now one full turn tall, centred on your zero. Put the design astride the crosshair rather than starting at it, so the engraving wraps half each way from the crest instead of climbing off down one side. Lùmen has a Center design on zero button that does exactly that.
Keep it modest in height to begin with. Geometry is unforgiving here: a design that wraps 70° of a 42 mm object puts its top and bottom edges some 4 mm below the focal plane, and hits them at a glancing angle.
Press Frame. The object rolls back and forth through the extent of the design — which is the clearest preview there is of where the engraving will land, and the cheapest way to catch a design that has ended up off the object entirely.
If the frame looked right, run it.
This is the part worth taking seriously. Rotary mode rewrites a calibration setting in the controller's own memory — it survives the app being closed, the USB cable being pulled, and the machine being switched off at the wall. A machine left in rotary stretches every later flat job in the Y direction, silently, with nothing on any screen to say why.
So Lùmen reads your machine's flat value when it first connects, keeps it, and writes it back with one button: Back to flat bed. Press it when you're done. If you ever connect and the machine's settings don't match either configuration — because something else changed them — Lùmen says so and offers both ways out rather than guessing.
It won't home while the rotary is on — the command is refused, in the live stream and in an exported file alike — and it asks before any homing that would happen as a side effect on a machine that owns a rotary, because it cannot see whether the cable is plugged in. It also won't let you sit in Machine Home mode with a rotary active: that mode's whole premise is a homing cycle.
Reach out to support with your machine, your rotary and the two numbers you entered. If the head is going somewhere unexpected before the rotary is even involved, start with the wrong-position FAQ; for power and speed on the material you're engraving, see the laser engraving settings chart.