# Best rock tumblers for agates: machines that handle long coarse runs Source: https://tumblegrit.com/best/best-rock-tumbler-for-agates Publisher: Tumble Grit. Picks are chosen from what each Amazon listing states, not from hands-on tests. Method: https://tumblegrit.com/how-we-pick Agate sits around Mohs 6.5 to 7, so it tumbles to a high polish but takes its time in coarse grit. Rough agate with pits, fractures or rind often needs two to four weeks of 60/90 before it is ready for medium, and a full run can pass six weeks. That puts more load on the machine than soft stones do, and it decides what to buy. A rubber barrel of 3 lb or more lets agates roll with enough weight to grind and cushions them against chipping. The motor matters most: it must turn a full barrel for weeks without overheating, which favors continuous-duty or brushless motors over the smallest kit machines. A timer that stops at 9 days is fine as long as you restart it. This guide compares seven tumblers that suit agate, from a budget 3 lb drum to a 22 lb workshop machine, plus a refill kit with rough agate. ## Picks ### 1. KomeStone G2 Dual-Barrel Professional Rock Tumbler Kit, 8LB for Adults KomeStone G2: two 4 lb rubber barrels on a brushless motor and reinforced metal base, with 3 speeds and a 9-day LCD timer with pause and memory. Kit includes 2 lb of rough in 9 named stones. What the listing offers: - Two 4 lb barrels are among the largest in this guide, for bigger batches or larger stones - Brushless motor rated by the maker for 40,000+ hours on a reinforced metal base - Pause and resume with settings memory makes mid-run checks easy Limits to know: - Upper price band for a kit tumbler, tied with the AtoRock - 3 speed settings, one fewer than the KoolStone and VEVOR machines ### 2. KomeStone G1 4LB Professional Rock Tumbler Kit for Adults Capacity: 4 lb; Barrel: Rubber; Barrels: Single; Timer and speeds: 9-day timer, 3 speeds A 4 lb single-barrel rotary tumbler on a metal base with a brushless motor. The largest single barrel in this guide, for adults who want bigger batches without moving to two barrels. Rough, a 4-stage grit set and 2 spare belts are in the box. What the listing offers: - 4 lb rubber barrel, described in the listing as thick tire-grade rubber, on a heavy-duty metal base with a brushless motor. - 3 speed settings and an adjustable 9-day digital timer on an LCD screen, with pause, resume and settings memory. - Listing says the motor, control panel, drive belt, rubber barrel and metal lid kit are each sold as replacement parts by KomeStone. Limits to know: - One barrel only, so each grit step waits for the one before it; the double-barrel pick runs two steps at once. - A 4 lb barrel takes more rock and more grit per run than the 2.5 lb and 3 lb machines, so supplies go faster. ### 3. KomeStone G3 22LB Professional Heavy-Duty Large Rock Tumbler for Adults KomeStone G3: a 22 lb barrel on a brushless motor with a full metal base and metal-clad drum, a smart panel that logs days and power use, and a stated 5-year motor warranty. What the listing offers: - 22 lb capacity takes large agate nodules and whole buckets of beach agates in one run - Metal base and drum shell are built for sustained heavy loads - 5-year warranty on the motor is the longest of any machine here Limits to know: - A full 22 lb load needs a lot of grit and rough per stage, which suits collectors with plenty of material - Highest price in this guide and a large, heavy machine to place ### 4. Thumler's Tumbler A-R1 Rotary Rock Tumbler w 3LB Barrel The entry Thumler's machine: one 3 lb molded rubber barrel on a metal frame with a fan-cooled, overload-protected motor built for continuous duty. For a hobbyist who runs one batch at a time. What the listing offers: - Continuous-duty, fan-cooled motor with overload protection suits the 1 to 2 week runs of each grit stage - Molded rubber barrel is quieter than plastic and is a stock Thumler's part that can be replaced - Lowest price in the Thumler's line, with the same frame and motor build as the two-barrel model Limits to know: - Single 3 lb barrel means one stage at a time, so a full 4-stage run on hard stone takes over a month - Machine only: the listing names no grit, media or rough in the box ### 5. KoolStone C1 Pro Max Professional Rock Tumbler Kit - Large 3LB Capacity & Brushless Motor, Up to 6X More Noise Cancelling, Ultra Quiet Rotary Polisher with Full Accessories, Ideal for Adults Kids KoolStone C1 Pro Max: a 3 lb rubber barrel on a brushless motor under a noise-reduction cover, with 3 speeds and a 9-day timer with auto shutoff and memory. Full kit with accessories. What the listing offers: - Brushless motor runs cooler over long coarse stages than brushed kit motors - Noise-reduction cover makes month-long indoor runs easier to live with - Timer memory and auto shutoff help track repeated coarse cycles Limits to know: - 3 lb barrel limits batch size and larger agate nodules - Kit contents are not itemized in the listing beyond the barrel and accessories ### 6. National Geographic Rock Tumbler Refill Kit with 1 Lb. Rough Agate National Geographic refill kit with 1 lb of rough agate from several sources, four grades of grit (coarse to polish), jewelry fastenings and a learning guide on agates. What the listing offers: - Rough agate plus all four grits in one box, sized for a small first agate run - Listing states the grit works with any rock tumbler, not just National Geographic models - Low price for a full stage set with stones included Limits to know: - 1 lb of agate only fills a small barrel; a 3 lb barrel needs filler or more rough - Colors and sizes vary from kit to kit, as the listing says ### 7. Leegol Electric Rock Tumbler Machine - Single Drum 3LB Rock Polisher (Single Barrel) Capacity: 3 lb; Barrel: Rubber; Barrels: Single; Timer and speeds: not stated A plain 3 lb rubber-barrel machine sold without rocks or grit. For adults who already have rough and grit, or who would rather choose their own than take what a kit includes. What the listing offers: - 3 lb rubber barrel with a double stainless steel top cover, described as leak proof. - Comes with five V-belts, so spare belts are in the box from day one. - Includes 0.5 lb of walnut shell media and instructions. Limits to know: - No grit and no rough rocks in the box: silicon carbide grit for the four steps has to be bought separately. - No timer or speed settings are mentioned, and the listing says a screwdriver is needed to open the lid. As an Amazon Associate I earn from qualifying purchases.