Homing¶

The machine has no limit or home switches as it ships. This page tells you how the machine finds its origin with the cameras, how you can set it by hand, what the machine does without one, and what each homing setting means.

The mechanism, the homing runner and its handover, is in Homing internals.

The homing method is a setting¶

homing_mode, on the panel's Machine tab, selects what $H does. The controller re-reads it on every $H.

Camera-referenced homing¶

$H from any sender runs the factory-style camera homing cycle through the Glowforge service. The service takes a lid image, moves the head, takes another, and computes where the head is; the machine moves to the home corner. The service's lens hunt is answered as done without moving the lens; after the session the lens takes its own reference on the hall sensor's edge, and Z is set to the focal point's height at that edge: above the tray, the number Setup measured, or above the floor when the crumb tray is out. The lens then moves to the park height, lens_park_z_mm on the Machine tab (default 3 mm), so a home ends focused about 3 mm above the bed.

• It needs a Glowforge account and a live service session. This is the one part of GRBL mode that reaches the Glowforge service; everything else in GRBL mode runs without it. The cycle uses the machine's own credentials (the factory fuse identity, or the overrides on the GF Cloud tab; see Cloud mode) and names its software as ForgeFIRM.
• It needs the lid closed. The camera steps need it, and the move to the home corner is an ordinary motion action: refused with the lid open, and stopped if the lid opens partway through. The lens reference after the session does not need the lid.
• It takes about a minute. A full cycle runs in 50 to 65 s. While it runs, $H suspends the stream engine, runs the session, and hands the machine back; your sender keeps getting status reports.
• It can fail or time out. gfcloud_home_timeout_s (default 300 s) is the budget for the whole session (sign-in, camera uploads, hunt, and corner moves). Past it, or on a failure, the controller alarms (ALARM:18) like a failed core homing cycle. A soft reset (^X) aborts the session (ALARM:6). X and Y are then not homed, and the lens is held where it stands until the next home: home again before you trust the coordinates.
• A quiet service is not a homing. The cycle counts as complete only when the accelerometer in the print head witnessed real motion during the session. A service that goes quiet without moving the head is a failure.
• The ok comes at the end. Your sender's ok for $H arrives when the session ends; the status reports keep coming meanwhile.
• After a home the bed is the limit. A program move past the bed alarms before it moves (alarm 2), and a jog past it is refused (error 15). The limits go with the reference: an underrun or a stream fault takes both.

After a successful home the position is anchored and the panel shows it normally. The home corner is the back-left corner of the bed, and the workspace is all-positive from there (+Y runs toward the front of the machine; Z counts positive upward). gfcloud_home_x/y on the Machine tab set the machine X and Y the head is at after a completed camera homing (defaults 0 / 0): leave them blank until a measurement says otherwise. They may be negative, when the origin you calibrated lies inside the factory home; the soft limits then reach back to the home position, since the head stands there. Camera homing alone uses them: no other homing method reads them, and the panel shows them only while camera homing is the method. Z after a home is lens_park_z_mm, the focus height the lens parks at; the setup's Focus burn measured where the hall edge sits in that frame. To calibrate: home, jog to a known reference, and enter the measured offsets.

Do not let a sender home automatically on connect: LightBurn's Auto-home on startup stays off, and you run $H deliberately from its Console tab when you want a true machine origin (LightBurn).

Manual homing¶

With homing_mode = manual you are the homing cycle. You push the head into the home corner, and $H takes your word for it.

1. Release the motors: press Release motors on the panel's Machine tab, or send $MD. X and Y go limp so the gantry and the head move freely by hand. The machine stays on, and the lens is not released. The position is forgotten at once, and the machine locks: it reports ALARM:11 and refuses every move, from every source, until you end the release yourself. $X does not unlock it and a soft reset does not either, because your hands are on the gantry.
2. Open the lid and push the head to the home corner: the back-left corner, against the gantry stops. Push gently, and keep the gantry square to the machine as it goes back. Do not home against the bare factory corner: what the gantry meets there is springy, and what the head meets on the left is a cable.
3. Close the lid and press Set home here (Machine tab, shown while manual homing is the method), or send $H. The motors energize and hold, and the spot the head is in becomes X0 Y0. Z is left as it is (Running unhomed).

manual_home_x and manual_home_y, on the Machine tab, are how far from the gantry stops X0 Y0 is. Blank, the stops are X0 Y0. With 1 and 1, Set home here moves the head 1 mm off the stops in X and Y and makes that X0 Y0. The move never fires the laser.

The work area starts at X0 Y0 and reaches the axis travel, or what the Bed size check measured (Setup). After changing the offsets, run the check again.

To get out of a release without homing, press Energize motors (the same button, while they are released) or send $ME: the motors energize, and X and Y stay unreferenced until a home.

The panel's buttons and the $ commands are the same operations. The buttons go through the controller beside your Grbl sender, so the sender stays connected through the whole procedure, and its console shows each step. The Status tab shows X and Y motors: RELEASED for as long as the release stands.

The soft limits are only as true as your placement. After a manual home the bed is the limit, exactly as after a camera home, but the machine cannot check where you put the head. If the head was not in the corner, the whole envelope is shifted by the same amount, and a move the limits allow can still reach the frame. Your sender is told so at every manual home ([MSG:Warning: Manual home: position set where the head was placed. Soft limits may not match the machine.]). Home against the gantry stops, where an error leaves the far limits short of the far frame rather than past it.

$MD is refused while a program runs and while a laser job is armed.

Running unhomed¶

The machine cuts fine unhomed. Without a reference, X and Y are relative to wherever the head happened to be, so the panel shows them in red to say so, and your sender should use a job-start mode that does not depend on machine coordinates: in LightBurn, Start From: Current Position (LightBurn, Job start mode).

Z is the exception. The lens references itself against its hall sensor every time the machine brings a controller up, so focus heights are good without homing and Z reads its height while X and Y show as unreferenced. The panel's Homed row names the axes that carry a reference, so an unhomed machine reads Z only rather than a plain no. If the lens cannot find its sensor the machine refuses to run at all and the panel says why: that is broken hardware, not a state to work around.

Anything that invalidates position, an underrun, a stream fault, a soft reset whose position cannot be read back, a soft reset during a camera-referenced homing, or a motor release, drops the anchor deliberately, so a stale origin cannot be reused. Re-home before you trust coordinates again.

Homing in cloud mode¶

Cloud homing is automatic and camera-based; the service runs it when the machine connects and after prints. The lens hunt references Z against the hall sensor. Connecting zeroes the machine's counters at the head's current position, so GRBL-mode coordinates do not survive a switch to cloud mode and back: re-home after switching (Modes, Cloud mode).