Gantry types explained: XY, XYZ, H-gantry and dual-X
A Cartesian gantry is two or three linear actuators arranged at right angles. The layout — a stacked XY stage, a three-axis XYZ, an H-gantry with two parallel X rails under a Y bridge, or a dual-X gantry carrying a Z — decides how much payload and travel the system can handle and how stiff it is. Here are the six layouts the Engineering Decision Engine builds, what each is for, and the limits it enforces.
The six layouts
| Layout | Engine type | Structure | Best for | Typical kit |
|---|---|---|---|---|
| XY stage | xy | Y actuator mounted on the X carriage | Light loads, small footprints, dispensing, inspection | 2 × SBA45/SBA60 + BLC-2T |
| XYZ Cartesian | xyz | XY stage with a lead-screw Z on the Y carriage | Pick-and-place, lab automation, 3-axis positioning | 2 × SBA + LSA45 + BLC-4T |
| H-gantry | xxyh | Two parallel X rails, one Y bridge, no Z | Wide decks, flat-plane transfer, printing/dispensing over a bed | 2 × SBA + SBA bridge, paired axes |
| Dual-X vertical gantry | xxyv | Two X rails with the Y bridge on its side | Tall workpieces, loading into machines | 2 × SBA + SBA bridge |
| Gantry + Z (parallel or inline Z) | xxyvzp / xxyvzi | Dual-X, Y bridge, LSA Z on the bridge carriage | Full pick-and-place over a deck; the default 4-axis cell | LYNXSYS XX'YZZ-style, BLC-4T/6T |
| Elevated gantry | xxyvzpe | Gantry + Z raised on I-beam supports, tools work top-down | Conveyor pick-off, plate handling over instruments | As above + I-beam supports ($275 each) |
Stacked XY versus dual-X gantry
A stacked XY stage puts the whole Y actuator on the X carriage, so the X axis moves the Y actuator's mass (about 2.5 kg for an SBA45 with gearhead, 8 kg for an SBA90) plus the payload, and the Y actuator cantilevers out from one side. It is compact and cheap, and fine up to a few kilograms and a few hundred millimetres. A dual-X gantry supports the Y bridge at both ends on two parallel X rails driven in lockstep — paired axes on the controller — so the bridge is stiff over a wide span, the load is shared between two motors, and the deck below is clear. Above about 5 kg or 500 mm of Y travel, the gantry is the right answer; the engine sets the rail spacing from the Y actuator's overall length automatically.
Adding Z
Z is always a lead-screw actuator — LSA45 on an SBA45 system, LSA60 otherwise — because the self-locking nut holds the tool when power drops and the short vertical stroke suits a screw. Parallel Z mounts the motor beside the screw for the shortest overall height; inline mounts it on the end for the narrowest profile. The Z rating caps the system payload: 7 kg on an LSA45, 15 kg on an LSA60, regardless of what the belt axes could carry, and the engine states that cap on every build that exceeds it.
The limits the builder enforces
XY travel to 1,500 mm per axis (1,275 mm as a single catalog belt actuator; longer engineered). Z travel to 250 mm stepper or 500 mm servo. Payload to 25 kg stepper or 50 kg servo, further limited by the Z rating when a Z is present. Speed to 1,200 mm/s stepper or 2,500 mm/s servo. Rail spacing on dual-X types from 100 to 1,200 mm. Motors mount down by default on gantries (up on the elevated type, whose calibrated profiles assume it). Requests outside any of these are built at the nearest limit, the gap is stated in millimetres or kilograms, and the design is routed to an engineer with the sizing attached.
Choosing in practice
Start from the deck. If the tool works over a surface wider than about 500 mm or heavier than a few kilograms, it is a dual-X gantry; if it must reach down onto that surface, add Z; if the surface is a conveyor or an instrument that must stay clear underneath, elevate it. If the work is small and light, a stacked XY or XYZ costs less and is simpler to mount. Describe the task to the engine in a sentence — payload, travels, speed, and what sits underneath — and it picks the type, sizes every axis, and builds the 3D assembly you can export.
Size it yourself in about a minute
Type the task — payload, travel, speed — and the Engineering Decision Engine returns a validated, priced 3D system with the torque margins, inertia check, and cycle-time math shown. Free to design and quote.
Frequently asked
What is the difference between an XY stage and a gantry?
An XY stage stacks the Y actuator on the X carriage and cantilevers it; a gantry supports the Y bridge at both ends on two parallel X rails. Gantries are stiffer, carry more, and leave the deck clear.
What is an H-gantry?
A dual-X gantry with a Y bridge and no Z axis — two X rails driven in lockstep carrying a single horizontal bridge. It is the layout for wide flat-plane work such as dispensing or printing.
How are the two X motors kept in sync on a dual-X gantry?
The 4- and 6-axis BLC controllers support paired axes: both X motors run from one command as a single logical axis. The engine selects a paired-axis controller for every dual-X build.
How big a gantry can be built from the catalog?
To 1,500 mm per axis, 50 kg payload with servo motors (less with a Z), and 2,500 mm/s. Beyond that — 2,500 mm travel, 100 kg — the system is engineered from the same families.