Thumler’s Model B Review

Marc McDermott

The 15lb Thumler’s Tumbler Model B is an excellent choice for both serious hobbyists and professionals who need a no-nonsense, mid-sized machine.

What we like:

  • High-speed motor.
  • Hexagonal drum for even distribution of rocks and grit.
  • Removable rubber liner for quieter use.
  • Five-year guarantee on the barrel and liner.
  • One-year guarantee on the motor.

What we don’t like:

  • No on/off switch – needs to plug into a timer or an outlet with a switch.
  • The drum will not spin if an overload is detected.

Key features

Thumler’s Tumbler Model B is small but mighty. Measuring 14″x14″x14″ inches, it boasts a drum capacity of 15 lbs. This is a great size for both home and commercial use, ideal for the hobbyist with limited space, and the drum capacity is generous enough for a sizable collection of rocks.

This rock tumbler offers a 1550 rpm fan-cooled motor, a high-speed feature that polishes rocks and deburrs metal as quickly as a vibrating motor.

The 15 lb. steel drum has a unique hexagonal shape, aiding in the even distribution of rocks and polishing material.

The removable rubber lining limits noise levels while the device is in operation.

Since this rubber lining is removable and replaceable, switching between grit type or moving a tumbling cycle from grit to polish, is a simple matter of having replacement liners on hand.

A strong belt drive turns the barrel on nylon bushings, which also aids in the low-noise running.

The housing is cast aluminum on a strong steel base. There is a one-year warranty on the motor.

The barrel and liner are protected by a five-year guarantee.​

Ease of Use

It is simple to load and operate, suitable for a user of any age (though of course it should not be used by children unsupervised by an adult).

Being a mid-sized machine, the manufacturer assumes the purchaser is experienced and does not require an instruction manual – only a standard parts manual is included.

Response to wear and tear

This tumbler is extremely sturdy.

Since grit will inevitably accumulate on and wear out the liner and other components over time, a high-quality barrel and liner are crucial for the longevity of the tumbler.

This product features a steel drum with an efficient hexagonal shape, which will wear well for many years of tumbling.

The rubber liner in this tumbler makes for relatively quiet tumbling and can be removed and cleaned between uses.

This is especially great for the user who wants to use a variety of tumbling media for different projects – switching out among the grades of grit and polish or trying polypropylene or stainless steel pellets.

Ease of acquiring and installing replacement belts can be an issue, and fortunately, this tumbler has a long-wearing belt that is easily replaceable.

While this machine does not have an on/off switch, this is less of an issue than one might imagine.

Depending on the material being processed, the tumbler will need to run for several days at a time.

Most users will find it more efficient to connect the tumbler to a timer switch rather than counting on being there to turn it off themselves.

Bottom line: this is a heavy-duty professional quality machine at an affordable price point for the serious home hobbyist or small business owner.

How does it compare?

Let’s take a look at some comparable tumblers to see how they stack up:

Model B vs. Lortone QT-12

This Lortone rock tumbler is also a good sturdy machine, with a heavy-duty professional-grade motor, all-steel body, and a 10-sided molded-rubber barrel.

It has a smaller capacity at 12 lb. rather than the 15 lb. drum found on the Thumler’s Model B.

The rubber lining of the barrel is not removable, making this tumbler a little harder to clean and switch out finishing materials.

The Lortone also does not have an on/off switch, so like the Model B, it needs to be connected to a timer or plugged into a switched outlet.

This Lortone rock tumbler is a fine choice for experienced users and produces professional results for larger batches of rocks.

However, due to the slightly smaller drum, it might be best suited for those interested in jewelry-making or other pursuits where only small rocks are likely to be polished.

Model B vs. Thumler’s A-R12

This slightly smaller Thumler’s model offers the same sturdy steel and aluminum construction as the Model B, but with a 12 lb. capacity barrel.

It also does not have an on/off button, and requires the use of a separate timer or should be plugged into an outlet with a dedicated switch.

The A-R12 tumbler has an interesting and unique feature.

With the addition of small replacement barrels (sold separately), it can be converted into a tumbling machine that turns two 3 lb. barrels at once.

This is a terrific feature for those who want to run multiple batches at once that are in different stages of the tumbling cycle.

Like the larger Thumler’s Model B, the A-R12 features strong rubber-lined barrels for quiet motion, and the motor and barrel are covered by warranty.

Again, the smaller capacity is somewhat limiting if you’re looking to do larger rocks or large batches.

Final thoughts

​There is both art and craft to stone polishing using a rock tumbler. Paying attention, taking your time, and understanding the correct materials to combine to achieve the desired finished product are all crucial to the process

But even the most dedicated and experienced lapidary needs the right equipment to get the best results.

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