The Rake vs. The Drum: A Deep Dive into PetSafe's "OpenSky" Smart Litter Box
Update on Nov. 7, 2025, 6:57 p.m.
The automatic litter box market has, for years, been dominated by two distinct and competing engineering philosophies.
On one side, you have the “Rotating Drum” (or “Globe”). These are the fully enclosed, “smart” devices (like Litter-Robot or PETKIT) that spin to sift litter through a filter, dropping waste into a sealed drawer. They are high-tech, excellent at odor control, and packed with app-based features. Their primary drawback: they are enclosed, which can be a deal-breaker for very large cats or anxious cats who feel trapped.
On the other side, you have the “Automatic Rake”. This philosophy, long championed by the PetSafe “ScoopFree” brand, uses an open-top design. A rake mechanism slowly moves across a tray, pushing solid waste into a covered compartment. Its advantage has always been this “open-air” design, but it came with a massive, deal-breaking trade-off: it was only designed to work with its own proprietary crystal litter trays.
Now, that “cold war” is over. New hybrid devices, such as the PetSafe ScoopFree OpenSky (ZAL00-18120), are attempting to merge these two philosophies. This new generation aims to be the “best of both worlds”: the open-top ergonomics of a “Rake” combined with the “smart,” data-driven features of a “Drum.”
The Core Engineering Challenge: “Works with Any Litter”
The single most significant claim of this new device is that it “Works with Any Litter.” This is a revolutionary pivot for the PetSafe brand, and it introduces a massive engineering challenge.
- The “Drum” Method: A rotating drum uses gravity. It tumbles the litter, and the clean litter falls through a sifting screen. This is a very effective mechanism for clumping clay.
- The “Rake” Method: A rake pushes waste. For this to work with clumping litter, the rake’s tines must be perfectly spaced to allow loose litter (of any kind) to pass through, while being strong enough to push heavy, wet clay clumps without the tines gumming up, smearing the clump, or breaking.
This “any litter” rake is the central technology. It’s a high-torque motor dragging a sifting rake through a bed of potentially heavy, sticky material. Its long-term reliability against the notorious “cement-like” quality of some clumping clays is the primary engineering test this device must pass.

The Ergonomic Advantage: The “OpenSky” Philosophy
The “Rake” philosophy’s greatest strength is its open-top design. This is not just an aesthetic choice; it is a direct solution to the #1 complaint about “Drum” models.
As one reviewer (“Luna”) of the OpenSky noted, “I like that this one has a much more open design, since one of our cats is a large breed (24lbs).” This is a critical insight. A 24-pound Maine Coon or Ragdoll will often refuse to, or simply cannot, comfortably use a confined globe. The “OpenSky” design provides the “space to move naturally” and “reduces your cat’s fear of entry,” making it an ideal choice for large, elderly, or anxious cats.
However, this open-top design has its own well-known trade-off: litter scatter. The same reviewer (“Luna”) confirmed this, stating, “I DO wish this specific design had a soft silicone lip or border so that cats didn’t kick litter out when they jump out.”
The “Smart” Integration: Health Monitoring on a Rake
The second major “hybrid” feature is the integration of an app-controlled health monitoring system. This is PetSafe bolting the “brains” of a “Drum” model onto its “Rake” chassis.
Like its high-tech competitors, the OpenSky app tracks: * Cat’s Weight: Using sensors in the base. * Litter Box Usage: Logging the frequency and duration of visits.
This is a powerful preventative health tool, as changes in weight or frequency can be the first signs of serious feline illnesses like kidney disease or a UTI.
However, the user reviews suggest this “smart” integration may be less mature than its competitors. “Luna” noted that the “app doesn’t have many options, so you have to use the buttons on the unit to level the litter – which I think is a bit weird.” This suggests a potential disconnect between the app’s capabilities and the machine’s required functions, a common “version 1.0” software quirk.

The Physics Problem: Where “Smart” Meets “Carpet”
Any “smart” device that claims to weigh your cat relies on high-precision load cells (weight sensors) in its base. This introduces a universal, non-negotiable point of failure that is critical for owners to understand.
These sensors must be on a hard, flat, level surface to get an accurate reading. If you place the device on a soft surface like a plush carpet or a bath mat, the carpet will “absorb” the weight and the sensors will fail. This can lead to a cascade of errors, from inaccurate health data to the machine failing to run its cleaning cycles.
Conclusion: A “Best of Both Worlds” Hybrid?
The PetSafe ScoopFree OpenSky is one of the most interesting market entries in years. It represents a direct attempt to solve the “big cat” ergonomic problem of enclosed “Drum” models, while simultaneously adopting their most popular “smart” features (health monitoring) and shedding its own biggest limitation (the “proprietary litter” requirement).
It presents the consumer with a clear choice of trade-offs: * You Get: An open-air, app-controlled box that is perfect for large, anxious, or elderly cats and provides valuable health data. * You Risk: Potentially higher litter scatter (due to the open top) and the unproven, long-term effectiveness of a rake mechanism against the notorious stickiness of clumping clay litter.
For an owner whose 24-pound cat simply refuses to use a “Drum,” this “Rake” hybrid isn’t just an option; it’s the only option.