I’ve been making a lot of jewelry lately, and my tumbler’s been working overtime. Over the past weekend I noticed that my barrels stopped turning. This happened intermittently, at first. The barrels would slip and sputter. The problem eventually worsened over the next couple of days. I finally had to reduce the weight on my tumbler to just a single barrel in order to keep at least one barrel in action.

This is a common problem with jewelry tumblers that’s caused by perfectly normal wear and tear on the drive belt. And it’s super easy to fix! It requires two basic hand tools that you probably have on hand and about five minutes of your time. So, don’t worry. We’ll have your tumbler up and running again in a jiff!

About This Tutorial

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My tumbler is a Loretone Model 33B dual barrel tumbler. I’ve only ever owned Loretone tumblers. It’s a name that I know and trust, and I’m quite familiar with the brand. This tutorial applies specifically to Loretone rotary tumblers.

I use and recommend the Loretone Model 33B dual barrel rotary tumbler. Here's a closeup of the manufacturer's specifications tag.

That said, most rotary tumblers have a similar drive mechanism. These instructions may apply to other brands of tumblers. However, I am not responsible for any damages that may result from attempting to apply the routine tumbler maintenance technique covered in this tutorial to a different brand of tumbler.

If you’re not comfortable working on electromechanical devices, I recommend referring to your owner’s manual or seeking assistance directly from the manufacturer of your tumbler before attempting to make any adjustments or repairs on your tumbler.

Why Did My Tumbler Barrel Stop Turning?!

There are a couple of reasons that can cause your barrels stop turning . But the most common reason, by far, is that your drive belt has simply stretched and lost its tension over time.

This is the result of perfectly normal wear and tear. As your tumbler runs, the drive belt slowly breaks down due to friction on the pulleys between the motor and the drive rollers. As the belt gradually wears out, it loses tension. Eventually, the belt won’t have enough tension to effectively drive the barrels.

You’ll know this is happening when your barrels start to slip or they stop turning entirely as mine did. In the case of a dual barrel tumbler like mine, you may also find that the drive no longer has the oomph to roll two barrels at once.

How Do I Fix It?

First things first. We have to determine if this is indeed just a loose belt or if your belt is actually broken. And we do that by taking a look under the hood.

Gather Your Tools

The only tools needed for this routine repair are a Phillips-head screwdriver and either a 5/16″ socket or a small adjustable crescent wrench (not pictured).

I used a socket because I happened to have one on hand. But an adjustable wrench works just as well.

The tools needed to tighten the drive belt tension are pictured here and itemized above.

Before proceeding, unplug your tumbler. Never work on a an electrical appliance while it’s plugged in!

Let’s Take a Look

Once your tumbler is safely unplugged, set it on a flat sturdy surface, such as your workbench. Then use a Phillips-head screwdriver to remove the screw and plastic washer on the barrel side of the housing cover, as shown below.

Remove the screw and plastic washer on the front of the motor housing to remove the cover, as shown.

The Anatomy of a Rotary Tumbler

A rotary tumbler is a super simple machine that consists of a small but mighty drive motor and a drive roller mechanism. The motor is harnessed to the drive roller with a small rubber belt. And it’s that belt that we’re going to inspect.

Can you see how much slack there is in my drive belt? It’s so loose that I could easily remove and replace it right now if I wanted to.

The drive belt is visibly loose, as shown in this image.

I like to get as much mileage as I can out of my drive belts, though. So I’m going to try adjusting the belt tension first.

This will buy me some time to locate my spare replacement belts, which are packed away in a box that’s been in storage since we moved into our current apartment nearly two years ago. So, it’s been at least that long since the last time I had to change the drive belt.

If you use your tumbler frequently, you will need to replace the drive belt at some point. That’s a normal maintenance task that you can expect as long as you own your tumbler. So it’s always a good idea to keep some spare replacement belts on hand.

How to Adjust the Belt Tension

Take a look at the end of the motor housing and you’ll see three small cap nuts on slotted holes. The cap nuts cover the mounting screws that secure the drive motor to the housing. And those slots are designed to allow you to adjust the drive belt tension.

Use your socket or adjustable wrench to loosen those three nuts just enough to let the motor slide.

Loosen the three cap nuts that secure the motor to the housing, as shown.

Then, using the fingers of your free hand, shift the motor toward the side of the housing until the mounting screws reach the other ends of the three slotted holes.

Use your free hand to slide the motor until the mounting screws reach the opposite side of the slotted holes, as shown.

Hold the motor securely in place with your free hand while you re-tighten the cap nuts.

Re-tighten the cap nuts to secure the motor in its new position, as shown.

That’s all there is to it! You should be good to go at this point. So go ahead and replace the housing cover, as shown.

Replace the motor housing cover and tighten the mounting screw, as shown.

Set your loaded barrel(s) back on the tumbler and power up the motor. You should be right back in business with a tumbler that’s rolling like a champ!

Now’s a good time to give your repair a solid test drive. And you might as well clean your steel shot while you’re at it. You know, two birds. One stone.

That did the trick! My tumbler is back in operation.

Thank You!

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Until next time, go make something beautiful!

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If you use your tumbler as often as I do, your barrels will inevitably stop turning. This is the result of normal wear and tear. And there's a quick and easy fix to get your barrels rolling again! Learn how in this free tutorial!