Xiaomi Mijia Electric Grinder Set

Xiaomi Mijia Rotary Tool Kit | Brushless Coreless Motor | 15,000–22,000 RPM Stepless Variable Speed | Dual Mode: Battery + Plug-In | 800mAh / 60-Min Runtime | Type-C Charge — 90 Min | 2cm Slim Anodised Aluminium Pen Body | 2.35mm Collet Chuck | 16 Bits Included: Diamond + Abrasive + Rubber + Wool + Drill | Auto-Lift Storage Case | 184×20×20.6mm / 310g | Wood Carving — Engraving — Grinding — Polishing — Drilling

The Xiaomi Mijia Rotary Tool Kit is a compact, pen-format brushless coreless motor rotary tool with a 2cm slim anodised aluminium alloy body, dual battery and plug-in operating modes, a stepless 15,000–22,000 RPM speed range controlled via a single knob, and a complete 16-piece accessory set covering diamond grinding, abrasive grinding, rubber polishing, wool polishing and precision drilling — stored in an ABS case with an auto-lifting bit compartment. At 310g and 184mm long, it is designed for single-hand precision craft and workshop work including wood carving, metal and model sanding, jade and jewellery polishing, glass engraving, rust removal and pendant hole drilling — applications where the pen-grip format and stepless speed control give significantly more control than a full-size angle grinder or rotary tool with a traditional pistol grip.

The brushless coreless motor is the performance specification that distinguishes the Mijia Rotary Tool Kit from brush-motor alternatives at the same price point: brushless motors eliminate the carbon brushes that wear progressively in brush-motor designs, extending the motor’s service life significantly; coreless motors (as opposed to conventional iron-core brushless designs) eliminate the cogging effect — the uneven resistance that brush-motor and iron-core brushless motors produce as the rotor rotates past the iron poles in the stator — producing smoother, more consistent rotation at any speed point in the 15,000–22,000 RPM range. The smooth rotation is particularly important in fine polishing and engraving where uneven motor resistance produces visible surface patterns in the finished work. The stepless speed adjustment knob allows continuous speed setting between 15,000 and 22,000 RPM without discrete steps — the user holds the knob at the resistance point that produces the right balance of cutting speed and control for the material and accessory being used, and the speed remains constant at that setting under load until the knob is moved.

The 800mAh lithium-ion battery provides approximately 60 minutes of continuous runtime at maximum speed under no-load conditions — sufficient for most single craft sessions. The dual operating mode allows the tool to be plugged in via the 5V⎓3A connection for extended sessions without the runtime limit: when plugged in and running, the tool runs from the power supply and the battery does not charge; when plugged in and idle, the battery charges. The Type-C charging port charges from 0 to full in approximately 90 minutes at 5V⎓1A. The 2.35mm collet chuck accepts all standard 2.35mm-shank accessories — the industry standard shank diameter for hobby rotary tools, compatible with a wide range of third-party accessories beyond the included set. The accessory attachment and removal requires no wrench: the pen-tip collar is twisted to lock and release the collet, holding the shank securely without tools. The 16-piece included accessory set covers: diamond grinding bits (for fine carving and grinding on hard materials including stone, ceramic and metal), abrasive grinding bits (for rough grinding and semi-finishing on metal and non-metal), rubber grinding heads (for fine polishing and rust removal on metal, plastic and glass), wool grinding heads (for surface polishing), a wool polishing wheel (for broad surface polishing) and a twist drill bit (for pendant holes and precise drilling). The ABS storage case features an auto-lifting bit compartment mechanism — when the case lid is opened, the bit tray rises automatically to present the accessories, eliminating the need to reach inside a flat storage compartment. The anti-roll case design prevents the tool from rolling off work surfaces. Soft rubber grip coating on the tool body for extended-session comfort.