Printer shapes: bedslinger, CoreXY and delta

Two FDM printers can lay down the exact same bead of plastic and still give you different parts, because the thing carrying the nozzle around matters as much as the nozzle. How the machine moves its axes decides how big a part you can print, how fast it stays accurate, and whether the sharp corner you drew comes out sharp or smeared into a set of echoes. You don't design for a brand — you design for a motion layout. There are three worth knowing, and each does something specific to your geometry.

Bedslinger: the bed moves in Y

The most common desktop layout, and the one most people learn on. The nozzle moves left-right (X) and up-down (Z); the whole bed slides back and forth in Y, carrying the growing part with it. It's cheap, simple, and everywhere. The weakness is right there in the name: on every Y move the machine is flinging a heavy bed — plus your part — back and forth. That mass limits how fast it can go before the whole frame starts to rock, and on a tall part the wobble gets worse the higher you build, because the part is a lever with its base clamped to a shaking table. Print something tall and skinny on a bedslinger and you'll often see the surface degrade toward the top.

CoreXY: the head moves in X and Y, the bed only drops

CoreXY keeps the bed still in the plane — it only lowers in Z as the part grows — and moves a lightweight printhead in both X and Y using two motors driving a clever belt loop. Because the moving mass is small and the frame is usually a rigid closed box, CoreXY holds accuracy at higher speeds and handles tall parts far better: the part sits still on a bed that barely moves, so it isn't being shaken. This is why serious and fast machines trend CoreXY. It costs more and there's more belt to tension and keep square, but for tall or demanding geometry it's the calmer platform.

Delta: three arms, a tall round volume

A delta looks nothing like the other two: three vertical towers, three arms meeting at a floating nozzle, a round bed that never moves. The three towers coordinate to place the nozzle anywhere in a tall cylindrical volume. Deltas can be very fast and are natural for tall, round parts like vases and columns. They're fussier to calibrate — the geometry is unforgiving — and the round bed is an odd fit for wide rectangular parts, but for height they're hard to beat.

What the architecture does to your model

Two things cross straight into what you draw. First, build volume is a hard constraint on part size. Every machine has a box (or cylinder) it can reach, and a part bigger than that box simply cannot print in one piece — you must split it in the model and design the joint: dowels, screw bosses, a glue lap, a dovetail. Designing for assembly isn't a compromise you make later; it's a decision the build volume forces at the start. Second, a shaky architecture pushed too fast produces ringing (also called ghosting): when the nozzle whips past a sharp corner, the machine overshoots and rings like a struck bell, and that vibration prints as faint repeating echoes of the corner rippling across the flat wall beside it. It's the sharp features you drew coming back to haunt the surface. A demanding layout — a fast bedslinger, a tall part — rewards you for rounding corners with a small fillet and not clustering crisp detail where the head has to change direction hard. That's a modelling choice you control. When ringing shows up on a print, When a print fails walks through chasing it down.

Motion is only one axis of the machine, though. Some parts don't want a nozzle at all — they want light and a tank of liquid. Next, see how that process works in How resin (MSLA) printing works.