The short answer: the ATOMSTACK A20 Pro V2 is the safer machine with the bigger bed; the LONGER Ray5 20W runs jobs without a laptop and carries the better owner rating. Both are 20 W. Pick on safety sensors and bed size, or on offline running — the cutting performance is close enough that it will not decide it for you.
Two open-frame diode machines at nearly identical money, bought by the same person for the same reason: to find out whether they like this hobby before spending real money. Both are 20 W, both run free software, and between them they hold most of the owner reviews in this price bracket.
| ATOMSTACK A20 Pro V2 | LONGER Ray5 20W | |
|---|---|---|
| Optical power | 20 W | 20 W |
| Work area | 400 × 365 mm | 400 × 400 mm |
| Frame | Open, all-aluminium | Open |
| Safety sensors | Flame detector and gyroscope tip-over cutoff | Basic; check the current revision |
| Onboard control | USB stick, no laptop needed | Touchscreen, runs from a memory card |
| Air assist | Optional | Nozzle included on most kits |
| Laser spot | 0.08 × 0.10 mm | Comparable, varies by revision |
| Top speed | 400 mm/s | Comparable |
| Cuts 3 mm basswood | Yes, one pass | Yes, one pass |
| Software | LightBurn, free LaserGRBL, or the ATOMSTACK app | LightBurn or free LaserGRBL |
Why the watts do not separate these two
Both modules are 20 W optical, and both get through 3 mm basswood in a single pass. Spec sheets at this price quote numbers that were measured in different ways, so treat the cutting-depth claims on either listing as the best case rather than the typical one. What actually differs is everything around the laser.
The A20 Pro V2 gives you a slightly shorter bed in one axis and an aluminium frame that stays square. The Ray5 gives you 35 mm more depth and a touchscreen. Neither difference will change what you can make.
The safety sensors are the real differentiator
ATOMSTACK builds a flame detector and a gyroscope into the A20 Pro V2, so a knocked frame or a flare-up on a cutting pass cuts power. On an open frame, with nothing between the beam and the room, that matters more than a spec sheet suggests. It does not make the machine safe to leave running — nothing does — but a flare-up is more likely to stop the job than start a fire.
Who should buy which
ATOMSTACK A20 Pro V2
You want the sensors and the aluminium frame, and you are happy to drive it from a laptop or a USB stick. It has the longest owner-review history of anything in this bracket, which is worth something on a machine nobody will service for you.
Check price on Amazon
LONGER Ray5 20W
You want to start a job and walk away from the laptop. The onboard touchscreen runs from a memory card, which turns out to matter on long cutting runs, and it carries the higher owner rating of the two.
Check price on AmazonQuestions people also ask
Is the ATOMSTACK A20 Pro V2 good for beginners?
It is one of the better open-frame starts because of the flame and tip-over sensors, the big bed and the free software. It is still an open frame, so it needs glasses, ventilation and supervision.
Is a 20 W diode twice as fast as a 10 W?
For cutting, roughly — fewer passes through the same stock. For engraving, barely, because engraving is limited by travel speed rather than power.
Do either of these engrave metal?
Only coated, painted or anodised metal, or bare metal treated with a marking spray. Neither engraves bare stainless steel.
Can I run them with free software?
Yes, both work with LaserGRBL at no cost. LightBurn is worth buying when the free app stops you doing something specific.