Which 3D Printer?

There are many internet resources for 3D printing which give much more in depth information about 3D printing, but this document attempts to simplify the process of choosing a suitable machine.

This page only talks about FDM (fused deposition modeling) printers, as these are by far the most user friendly, cleanest and the cheapest way to get into 3D printing.

FDM printers work by feeding a plastic filament into a heated nozzle to deposit a thin bead on plastic on to the part. The nozzle is then moved in the X and Y axis to build up a layer of the part and then the Z axis can be incremented and the next layer produced. Most small printers have toothed belts to drive the X and Y axis where rapid motion is required, and then a screw feed for the Z axis.

As a simple approach to selecting an FDM printer, the decision can be based on 3 points.
- print volume
- Feed system
- Nozzle temperature
In all three cases, the answer to these criteria very much depends on what projects are anticipated.

Print volume

Print volumes for most hobby printers tends to be in the region of 250mm x 250mm x 250mm. Some are slightly taller on the Z axis.
The BiQu B1 shown here has a print volume of 235mm x 235mm x 270mm.

Industrial models might have a bed of 500mm x 500mm giving the scope for much larger projects. A larger bed can also print a higher number of parts in one setting reducing manual interventions and maximizing the output from an overnight print.
However larger printers can be expected to be more difficult to level, due to the table size where a small angle of tilt translates into a larger Z-offset at the extremes. The same applies to belt lengths and guide rails which really need to be made to a higher accuracy to keep the same print accuracy over the larger area.

Among cheap printers, smaller is better in terms of print quality and accuracy, but at the expense of capacity.

Feed system

FDM printers work by feeding a plastic filament into a heated nozzle to deposit a thin bead on plastic on to the part, but the feed system can be direct feed or Bowden.
Most budget printers feature Bowden feeds, which is where the feed motor is mounted away from the print head and the plastic filament is pushed down a flexible tube to the hot end. These printers work well and have the advantage that the weight of the feed motor is not slowing the print head down. However, they struggle with flexible filaments. These can bunch up as they are pushed down the tube causing a jam. This is where a direct feed helps.
A direct feed uses the same kind of rollers to act on the filament, but it is mounted just above the hot-end and so the amount of material that needs to be pushed is greatly reduced. Consider a direct feed it you anticipate printing flexibles.

Nozzle temperature

PLA is by far the most common plastic to be printed, it is durable, UV resistant, fuel proof, available in many colours, and only requires a maximum nozzle temperature of 220°C. However, to print a greater range of materials, a higher temperature nozzle will give more possibilities. Many printers specify nozzles that go up to 265°C which will capture most of the materials available to date. Some example temperatures are:
PLA 180°C -> 220°C
ABS 210°C -> 250°C
PETG 220°C -> 250°C
TPU 210°C -> 230°C
Nylon 240°C -> 290°C