The Kobra 2 arrived during the period when every budget printer's packaging carried a large number followed by mm/s, and those numbers stopped describing anything a buyer could use. It is worth unpicking that here, because this machine is a fair example of the category and because the misunderstanding costs people money in wasted filament.
What an advertised speed is measuring
A printer's headline speed is the maximum commanded velocity of the toolhead. It is a real number and it is nearly useless, for two reasons.
The first is acceleration. Trace the perimeter of a 40 mm part and the toolhead is either gaining speed or shedding it for the entire move; the figure on the box is never reached even once. Only long uninterrupted straight sections get anywhere near it, and most parts have very few.
The second is melt. The hotend can only convert so many cubic millimetres of solid filament to liquid per second. Ask for more and the extruder skips, the walls go hollow, and you get under-extrusion instead of a fast part. That ceiling, not the motion system, is what limits nearly every budget machine, and the print time estimator shows the effect directly: past the flow ceiling, raising the speed input changes the predicted time by nothing.
The useful mental model is that speed settings are a request and the flow ceiling is the answer.
Two materials, honestly
A 260 °C hotend on an open frame gives a short list:
PLA — the machine's natural home, and it does it well. PETG — entirely comfortable at these temperatures, and the right choice for anything that will sit in a car or outdoors.
Everything else is a compromise. TPU works because the extruder is direct-drive, but slowly. ABS is technically within the hotend's range and practically outside the machine's, because nothing encloses the print. Filled filaments need a nozzle change first, and the harder engineering materials need a hotter hotend and a chamber, neither of which exists here.
That is not a criticism. Two materials well covered is a great deal more than most people use, and a printer that does PLA and PETG properly for very little money is a genuinely good product.
Where the price went
Understanding what was economised on tells you what to expect:
- Frame stiffness. Light extrusions and a moving plate mean ringing appears earlier than on a heavier machine. Reduce acceleration before speed.
- Fan noise. Cheap high-static-pressure fans are loud, and this class of machine runs them hard.
- The nozzle. Brass, so a single spool of anything filled will widen it.
- Bed flatness tolerance. The automatic levelling exists partly because plates at this price are not guaranteed flat, and it does its job — but probe at printing temperature rather than cold.
Running cost, and why it barely varies here
The steady wattage shown alongside was derived from other 220 mm open-bed printers rather than measured here, and at this size the derivation barely matters — an evening of PLA costs a few cents of electricity at every tariff in the regional table. Try it in the cost calculator and the filament price will swamp everything.
The line that separates one budget machine from another is the hourly machine rate, and that is really a question about longevity: a cheap printer still working in five years is among the cheapest ways there is to make plastic objects, and a cheap printer that dies in twelve months is one of the dearest.
The two commonest first-year complaints
The commonest first-year complaint on this design is the first layer being too high after the machine has been moved or the plate swapped, because the mesh and the Z offset are separate settings and only one of them was re-measured.
The second is filament grinding after loading a fast profile. When the drive gear pushes harder than the melt zone can absorb, the filament is what gives way, and the gear chews a flat into it. Either slow the profile down or widen the orifice so that fewer millimetres of travel are needed for the same plastic; the 0.6 mm page sets out what the wider line gives up.
Where a slightly dearer machine wins
Quiet and enclosed are both things this printer cannot be. Filled and engineering materials are the other gap, and a 300 °C machine costs slightly more while removing that ceiling permanently. If your parts are already near the plate limits, the Kobra 3 offers a larger plate and much more capable firmware for a modest step up.