DIY Rotary Tumbler

3D Modelling, DIY, Other Projects, Solid Edge / Saturday, May 1st, 2021

Hello everyone, I hope you are spending a nice day, I had a little time to spend today and I decided to share with you a little project that I made a year ago that I never had the chance to share before.

Let’s start from the beginning, as a knife make I always searched for new ways to finish my knife blades and handles so about 5 years ago I built a very simple and rustic rotary tumbler with a pvc pipe, some furniture wheels and my old cnc spindle motor.
The tumbler worked well but after some time it’s started falling apart and I decided to disassemble it.
So I remained without a tumbler for some years and then the last summer I decided to built a new one. This time I wanted to built a tough one that could last more, and with the added knowledge that I gained through my years as a mechanical designer, I started working on the project with a different approach.

This time I decided to use a similar design with a pvc pipe and some wheels under it to make it spin, but I used a sheet metal chassis and I decided to mount the wheels on two stainless steel shafts supported by flanged ball bearings

To make the barrel of the tumbler spin a the right RPM I choosed a geared motor that spinned at 200RPM and for the transmission I decided to use two identical toothed pulleys so I could have a 1:1 ratio on the wheels.
The rubber wheels then had a diameter of 50mm and touched the pipe in a section of Ø165mm so I had a 3:3 ratio that gave me 61RPM on the barrel. Just what I needed!

With everything laid out on Solid Edge I started ordering the components online.

I wanted the motor to spin for some time then slowly stop and change the direction of spin so that the tumbling media inside the barrel would mix better during the operation.
So I bough a LN298N DC motor controller and rigged it with and Arduino so I could program it to do exactly as I wanted.
Here you can see an initial test:

As the electronics was done I needed to build the mechanical parts so I called one of my friends that machined for me the ends of two M10 stainless steel threaded rods so they would fit snugly into the ball bearings.

Then I realized the technical drawings for the sheet metal parts and made them laser cut and bend.

They needed a little deburring and cleaning but after a bit of work they where finished.

Finally it was time for the assembly!

Here it is in action!

And here it is (a little dirty) after some months of proud work!

As you can see I’ve added a second wheel on the shaft connected to the motor because sometimes if the barrel got a little wet it would slip. Also I decided to remove the electronic components that made the motor change direction of spin because I couldn’t see a real improvement with this change of directions instead of the single direction (and the electronic components tended to overheat).
I hope you have enjoyed this little project and if you have some questions feel free to comment or contact me! Have a nice day!

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