Introduction: Printer Rock Tumbler - With Adjustable Speed, Leds, and Different Jar Sizes

About: Jungles my home _ College now my life _ Mechanical Engineer to be _ An adventurer at heart


Years back I stumbled on a printer coin tumbler hack that liquidhandwash had created. It caught my attention because I happened to have the exact printer sitting in my room waiting to be used for something.

Liquidhandwash had created a useful but simple solution for a need of a coin tumbler. On the the other hand, I couldn't think of any real good reason I needed a coin tumbler, so I stashed the idea in the back of my brain for later. I don't collect rocks nor coins enough to need a tumbler. Until...

I decided to make a mancala set as a gift for someone. I wanted small smooth rocks to use as the pieces of mancala set. I then revived the idea of a rock tumbler into my brain - besides, I always wanted to build one since I saw liquidhandwash's tumbler. :)

I have a tendency to make things more complicated than necessarily. That is what happened to this project. It started with simply modifying a printer to roll a glass bottle as liquidhandwash had done, but that was to simple for me. I then added a speed controller using a potentiometer. And what about leds? I added two of them just for the cool blue effect they give. Finished?- not quite. I set it in the corner of my room on a shelf that happened to have an old dvd player strapped to the bottom (I know it sounds ridiculous - I was young when I did that kind of stuff.) :) So, why not hook the rock tumbler to the dvd player so it can be turned on and off by the dvd player remote? That is what I did. I was then satisfied.

I never thought I would do an instructables on this, but with the coming of the Remix Contest I remembered it. I would love your vote!

All credit for the original idea comes from this instructables and to this guy with the awesome username.

It you want a cheap, simple, and cool rock or coin tumbler, read on!

Step 1: What You Will Need....


This project obviously requires an old printer. That shouldn't be hard to find. There seems to be no lack of broken printers so just look around a little. Thrift stores are especially a good source for them. The best one to use is the simple printer-scanner inkjet type. Other printers may work but might be harder to modify.

Power source:

You will need some sort of power source to run your tumbler from. The best idea is to use a dc power adapter that puts out 9-12.

And for the variable speed and leds:

Two leds and a resister for them

Lm 316 variable transistor - like this one.

Potentiometer - I used a 100 ohm one


I also added a toggle switch

You will also need basic tools to do this project - screw driver, hack saw, hot glue, ect.......

Be careful! I am not responsible for any accidents from building this or from using it.

Step 2: Gut It...

This is pretty strait forward - tear it apart - carefully. Take all the screws out that you see. Remove as much as you possibly can. The scanner part, mother board, printer cartridge part - everything goes. Be sure to save the old parts as many of those parts can be used for other projects.

Once you have just a shell of a printer you can move on to the next step.

Step 3: Cut It...

I wanted a way to view the tumbling jar through the glass of the scanner so all that plastic obscuring my view of the jar needs to go.

The best thing to use is a hack saw blade to cut through the plastic; liquidhandwash used a jig saw.

The pictures should show you what I did.

Step 4: Mount the Motor and Rollers...

Now for the rolling part.

When taking apart the printer, you should have seen a geared motor attached to a long roller that helps rolls the paper through the printer. That is what we need.

I mounted the motor in the exact same spot it was in. The other end of the roller was in a piece of plastic that I glued down with hot glued and strengthened with a piece of bamboo.

I wanted this tumbler to fit various sizes of jars so I put a piece of felt on one of the edges as you can see, to create a surface a small jar could roll on.

For a larger jar, I mounted another roller from the printer in the front where the paper comes out. It rolls in some metal nuts that are glued down. It would be best to size it with a glass jar you are planning to use.

The pictures tell it all.

Step 5: Try It Out....

Now that we have the motor and rollers in, it is time to test to see how it does spinning a jar. The jar is best if it is glass an has a screw on lid. I use a quart size jar.

The easiest way to test this would be just to hook the motor wires from the motor directly to a battery, but if you have your power adapter handy, it and two alligator cables would work.

Step 6: The Speed Controller and Wiring

The speed controller is a nice addition to liquedhandwash's tumbler. With the speed controller you can control the rate the rocks are tumbled and adjust it to be less noisy.

The speed controller is composed of a potentiometer and a LM 317 variable voltage transistor. It works well. You can see the pictures for how to wire it. I also added a heat sink to the LM because it can get quite hot.

In addition to the speed controller I added a toggle switch to turn it on and off.

All the wire were soldered to the components.

A break down of the wiring is here:

Negative from adapter goes to switch. From switch, negative goes to the potentiometer's middle tab, the negative wire for the leds, and to the motor.

Positive goes to the input pin of the lm and to the leds.

Negative from the potentiometers side tab goes to the adjusting pin of the lm.

The middle pin of the lm goes to the motor for positive.

Step 7: Leds and Power Source...

To add a little more "coolness" to this tumbler I added two blue leds to the printer case. They were simply soldered and wired to a resistor to limit the current before hooking them to the power source. If you are running the printer on 6v the leds can be wired in series, but if not you will need a 100 ohm resistor between them and the voltage.

Now that you have everything hooked up, it is time to put some power to this hacked printer. I used a old power adapter that has an output of about 13v. dc. Make sure your power adapter outputs a dc. voltage. I would recommend using a power adapter that outputs anything from 9 to 15 volts. Depending on the voltage the motor could get to hot after several hours of use. You will just have to test the various voltages the motor can handle.

Step 8: Start a Tumbling...

To tumble rocks, simply put them in a jar, put them in the tumbler, and turn it on. The rocks will continually tumble on themselves causing their edges to become smoother and smoother. It may help to add some sort of grit in the jar to help smooth them. It may take quite some time till you have really smooth rocks, but the tumbler can be left on for hours.

To tumble coins, you should do as liquidhandwash did here, and add rubber flaps to tumble the coins more. He also added things like lead shot, glass beads and sand to the bottle to help in the smoothing process. I have never tumble coins in my tumbler so, unfortunately I can't be much of a help to you there..

So, there you have it. A rock tumbler that cost next to nothing, yet looks great and works great. I was rather pleased with the outcome of my tumbler. Unfortunately, I never really used it because most of the rocks in our area are of a sandy consistency. Most of the rocks simply crumble in the tumbler - so much for small round rocks for a mancala set, and so much for your gift, sister in law. :)

I never thought I would post an instructables on this, since it was an almost direct steal from liquedhandwash, but when I saw the Remix Contest, I thought of it sitting in my room. So, here is the printer tumbler revived and revised.

Until I appear again,


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