Rotary Rock Tumbler with Speed Control

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Rotary Rock Tumbler

Compact rotary tumbler platform for polishing stones, sea glass, metal parts, and other small objects. Designed for simple and fast printing and assembly as well as inexpensive plug-and-play components without requiring programming or custom electronics.

 

The display indicates the relative motor speed from 0 to maximum speed, not a calibrated RPM value.

 

The tumbler can be used with various round containers. The glass jar shown in some images is for illustration only and is not recommended for tumbling hard rocks without a flexible insert (see TPU insert further below in the description).

Features:

• Inclined Roll Geometry: Keeps the container centered automatically during operation.
• Adjustable Speed Control: PWM-based speed control for different applications.
• Simple Assembly: Requires only a few inexpensive off-the-shelf components.

Technical Specs

overall dimensions (length x width x height)	201 mm x 211 mm x 95 mm
supply voltage	12 V DC
max. current	0.5 A
min. container diameter	60 mm
max. container diameter	250 mm
max. container length	170 mm

Bill of Materials

part	quantity	Amazon Affiliate link
Greartisan geared motor 12 V DC 200 RPM	1	https://amzn.to/43fsE6h
Aideepen PWM motor speed controller	1	https://amzn.to/3RMssc8
ball bearing 608ZZ	4	https://amzn.to/4dv98ax
O-ring 28 x 22 x 3 mm	18	https://amzn.to/3P9KILV
power supply 12 V DC (I > 0.5 A)	1	https://amzn.to/3PuevPi
M3x12 screws with cylinder head	6	https://amzn.to/4v1fIwR
at least 4 cables to connect motor, motor controller, and power supply
(optional) adhesive bumpers / rubber feet for the housing	4-10

required tools: screw driver, soldering iron

optional tools: super glue

Assembly Instructions

1. Wire motor, motor controller, and power supply

   Mind the polarity of each connection!

2. Mount motor
   Use 6x M3x12 screws.

3. Mount motor controller
   The controller should clip right into place. If it should be too loose, use tiny spots of super glue to fixate the controller to the housing.

4. Insert ball bearings into housing
   Apply moderate force.
   

5. Assemble rollers
   Slip all 18 O-rings onto the rollers.

6. Mount rollers

7. Install gears
   Apply moderate force. If needed, secure gears using a tiny drop of super glue.

8. (optional) Add adhesive bumpers or rubber feet to the underside of the housing. For heavier loads, these can help reduce vibrations and prevent the device from lifting or shifting during operation.
9. Done!

Compatible Container Insert

New: Finned Insert Variant
A second insert variant with integrated internal fins is also available as a parametric model. The fins continuously lift and redistribute the contents during rotation, resulting in more agitation and improved mixing compared to the smooth insert.

Smooth insert
I also designed a matching TPU Tumbler Container Insert for glass jars and similar containers. The insert:

• reduces noise during tumbling
• cushions impacts inside the container
• makes glass jars more resilient
• uses a TPU snap-fit lid system

The model is parametric and can be adapted to different container sizes.