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Tumbler Prototype - Quiet, Large, Simple, Effective

John Ditt

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I developed a prototype tumbler in early 2016 and shall attempt to complete the project in early 2017. I intend to produce plans, including a formal video, as a fundraiser for nonprofit smithing associations.

The tumbler is simple and low cost to build, fairly quiet, large and effective. The noise level in the video is greater than that in reality.

First step is to pickle the forged work in food-grade citric acid for 12 to 24 hours and then to neutralize the acid upon the work in a baking soda solution. The pickling causes the forge scale to become dust like. 

A rubber mat lines the interior of the 55 gallon drum and its two ends. Media to date has been 'drainage rock' from Lowe's; the rock is deeper than that shown in the photo. Tests have been both dry and wet tumbling. The photo of bent nails show the results after just 20 minutes of tumbling.


Fontana Forge Tumbler Interior.jpg


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  • 9 months later...


Greetings to you in Finland, where I worked in the summer of 1972 as part of my college education in civil engineering. It was a factory for the production of aerated concrete panels and blocks, in the suburbs of Helsinki.

Between February and August 2017, my development of the tumbler was dormant.

The first tumbling media was industrial ceramic, but this particular media is intended for vibratory tumblers. The second tumbling media was 'drainage rock' as shown in the first photograph. But, both of these media fractured and generated thick dust.

So, I have started an experiment of aluminum bits as the tumbling media. Remember that the task is to remove the dust of the scale after pickling in citric acid.

I am shearing aluminum rod and angle to create bits and flattening, shearing and bending soda and beer cans.

By December, I should know the effectiveness of the aluminum bits in removing the scale dust and polishing the bare steel.

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Try steel cut offs and shot in sawdust for the media. It won't produce dust and the saw dust is surprisingly abrasive but soft so it preserves fine detail. Also, the finer the mineral media the more slowly it is reduced to dust. Try starting with sand.

How many RPM are you turning it?  Is there a lifting lug?

Frosty The Lucky.

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Frosty, Since the motor is 1/2 HP, I am striving for a moderately low weight load of work and media. Steel cut-offs that would fill one-third to one-half of the 55 gallon drum would be too heavy for the motor and the pulley system, I believe. Thanks for the idea of sawdust and/or sand; I know that the brass polishers use walnut shells, available from pet stores.

This tumbler turns at 21 rpm. There is no lifting lug. I created a hinged door in the drum's lid.

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A smaller amount of media is required if you have a say 3 stirrers (paddles) on the inside of the length of the drum (think clothes dryer). These keep the media from sliding and actually mix the media and metal during the rotation.

Nails 8 penny or less, small metal cut offs, nuts and bolts, all can work as media, and produce a hammered finish to the metal. Smaller media is less aggressive than larger media and can produce a matt finish to the metal.

There should be a way to remove the rust, dust, and etc from the media in order to keep the airborne debris down and to keep the media clean and fresh. 


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Thanks, Glenn.

In regards to paddles, the industry literature describes how the work should slide across and with the media rather than tumble or fall (due to paddles). This sliding of the work is not the sliding/slipping of the media. The hexagon interior of rotary tumblers serves to prevent the sliding/slipping of the media.

To date, the lining of my circular tumbler by the rubber mat seems to allow for the sliding/tumbling and to prevent the sliding/slipping of the media. In time,  I shall place a acrylic sheet in lieu of the steel lid of the drum in order to video film the tumbling inside the drum.

I am thinking of attaching a vacuum hose to the very center of the drum's back end to remove the dust.

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Would static electricity help to lessen the dust? I am alluding to the products know as Cottrell, Lurgi, & other similar electrostatic precipitators. (different types that can work either dry or in wet systems).

Try this reference for a quick overview of the subject.


The devices are designed for industrial and home use. (e.g. some smokers often have one in the house).

Is there any I-Forge Iron member with hands on experience with these devices? I'd love to read your input.

Incidentally, Mr. Frosty is correct. Saw dust is surprisingly abrasive.

Also paper.

Fine expensive chef's knives should NOT be used for cutting paper. They trash the blades.

So cut paper with a cheap knife or scissors.

Regards to all from here in the central U.S.A.


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J. D.,

The electrostatic precipitators was just a suggestion for consideration.

I am not expert enough in the subject to start a new topic on same.

But I think that a person with some electrical knowledge might be able to jury rig such a set up.



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