Best rock tumblers for agates: machines that handle long coarse runs

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

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.

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

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

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

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

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.