By Jeff Brown (New Zealand)

All right then (strategic pause). So here’s the facts that contribute to the dilemma (second pause).

I do my fair share of shooting. A considerable amount of this shooting is carried out utilizing cast bullets. The combination of the residue from burnt powder, cast bullet lubricant, sizing lube, general dust and grime and repeated shooting make my cartridge cases very grubby. Dirty cases are not ideal as, in addition to not looking very pretty, they are difficult to clearly detect brass fatigue such as splits in the necks or eminent head separations in and can be the cause of feeding and extracting problems. Logically then the most obvious solution is to clean the cases. Short of sitting down for hours on end with a tin of Brasso and a buffing cloth a case tumbler is the only answer.

Case tumblers are dinky pieces of equipment that use a mildly abrasive buffing media (usually crushed walnut shells) to polish away all the foreign material that builds up on cartridge cases. The tumbler functions by way of vibrating the media and cases in such a way that both continually rub past each other with the end result being shiny brass. Most of the major reloading component manufacturers make a case tumbler of one size or another but are quite costly and this is where my dilemma begins.

You see….basically I am frugal with my money. Some would say mean. It comes from being raised in Dunedin with all that Scottish influence and having a father who witnessed the Great Depression (what was so great about it?) first hand. As such I am always looking for alternate methods of acquiring necessary items other than parting with my hard earned cash.

Antipodean Technology

If I am too mean (mean = cheap in New Zealand joe b.) to buy a case tumbler the next best option is to build one.

Enter Craig. My good shooting friend Craig is a very practically inclined individual who earns his crust in the construction business. It was he who first planted the seed with his mark one model tumbler the materials for which consisted of simply a 2 liter (1/2 gallon) ice cream tub, an electric motor extracted from an old fan heater and some lacing wire to suspend it all. He attached the motor to the under side of the tub, fitted an offset bush to the motor shaft in order to unbalance the unit and create a vibration, filled the tub with walnut shells and cases, hung the assembly up and set it running. In view of how incredibly filthy his .45 ACP brass was (he is famous for it) a mandatory over night soaking in gasoline was undertaken prior to treating in the tumbler. The result, after many hours of tumbling merrily in his basement, was better than factory shiny brass the likes of which I have never seen in his possession. Had I not seen it I would not have believed such and simple device was capable of such feats.

Actually, the sole reason for building the tumbler was than the new barrel he was forced to purchase for his .45 auto which had a much tighter chamber that the old barrel. The original factory barrel would not only feed extremely dirty cases but also feed a full stack of spent cases straight from the magazine! Now THAT is a generous chamber. Of course the new barrel being tighter in the internal dimensions was not having a bar of Craig’s grimy shells.

With the success of Craig’s appliance I thought it would be almost rude not to build one of my own.

Research & Development

Now, at risk of offending a good friend it is fair to say that Craig’s mark one tumbler was not the prettiest device ever created. Actually it was quite agricultural in its construction though, in fairness, like many pieces of improvised Kiwi farm equipment (e.g: the Taranaki gate) its simplicity did not detract from the flawless functioning. The 2 major shortcomings that I could see with the mark one tumbler were lack of an air tight lid to prevent dust from escaping and the inability to sit the media/case receptacle flat on the floor/bench due to the motor being mounted on the underside permanently.

I had a vision of a free standing arrangement with the vibrating mechanism attached in a way that it was still able to move uninhibited. The plan would be to build a box large enough to act as a housing it which the operating components would sit. There would need to be sufficient clearance between the walls and floor of the body of the appliance that the container holding the media and cases could vibrate without touching anything rigid that would dampen the motion. 

To determine the dimensions of the box first I had to establish the measurements of the bit that would do all the work would be. I liked the idea of using an ice cream tub as they are freely available and disposable. The tub would then need a base to sit on but not be attached permanently to so the two could be separated for convenience. The base would bolt to the motor, which would be the source of the vibrations. Allowing for the width of the bottle the base would have to be 8 inches square and with 2 inches either side for free movement the box would need an inside measurement of 1 foot square.

My other passion besides shooting is mountain biking and as any off road cyclist will testify there is never a shortage of ruined bicycle tubes knocking around in garages of respective owners with little or no practical use; or so you might think. Flattened out bike tube measures about 1 2/3 inch wide. I surmised that if 2 pieces of tubing were fastened across the top of the box housing spaced evenly and with a little slack in them they would make a great support for the base with motor attached to sit in supporting the tub holding the cases etc. This would allow the motor unit to shake until the cows came home completely without any dampening.

Construction

        A washing machine water pump electric motor was acquired from a local appliance repair agent for the grand sum of $20. These motors are around 75 watts and small enough not to be too bulky but powerful enough to get the job done. In order to make the motor create a vibration a weight in the form of a 170 grain cast bullet was screwed to one of the blades on the fan that was attached to the shaft which would generate an unbalancing effect. The motor was fitted to a 8 inches square base made from ¾ inch MDF (Medium Density Fiberboard) which in turn had a small edging fitted around the top to hold the bottle securely during operation. All of this then sat on 2 pieces of bicycle tubing secured with a small amount of slack across the top of a box also made from MDF. The tumbler was ready for testing.

Performance

Initial tests were very favorable though I could not get my hands on any walnut shells to use as buffing media. Another friend uses rice as a substitute for walnut so off down to the local supermarket I trundled and scanned along the bulk bins. Rice was $2.90 per kilo but barley was only $1.80 so being my usual frugal self I purchased a kilogram of the barley.  Who’s mean? Dumping the barley into the tumbler with a goodly dose of Brasso the appliance was set in action. Two hours later I had the cleanest .32-20 brass ever seen.

Success

Later I was given some walnut shell that has since replaced the barley.

     Unfortunately the success did not continue for as long as I would have liked. The washing machine pump motor was not of the best quality and during constant operation became very hot at which time the thermal cutout would kick in and shut the project down. Also, the position of the weight on the fan blade whilst creating a desirable vibration did nothing for the longevity of the motor. The bushes began slogging out and the tumbler began sounding like a skeleton throwing a fit on a tin roof. LOUD? Phewf.

The solution was to replace the mark 1 motor with a better quality piece with ball bearings and be more selective about the placement of the weight.

A suitable replacement was located which turned out to be 69 watts and though it was slightly less powerful it was a vastly superior in quality and did not get so hot or cut out.

I turned up a 7/8 inch long brass bush on the lathe from some 7/8 inch bar and mounted a long grub screw in it to act as a lock on the shaft and to hold the weight to unbalance the motor. Tests with increasing weights were conducted until the desired performance was met. The final combination was 2 flatten .50 caliber maxi bullets that I shoot in my muzzle loading rifle weighing 362 grains a piece. These are mounted on the shaft only 1/2 inch below the motor housing and within 7/8 inch of the shaft axis laterally. The new motor is working perfectly and is enormously quieter than its predecessor.

Something to consider when unbalancing an electric motor in this fashion is that they are not designed to operate like this. Such motors are tuned by the manufacturer to run perfectly true. By introducing an off center weight the motor is put under stresses that it is not designed to handle so the placement of the weight is quite critical as I discovered on the first motor.

Ideally a sufficiently large weight should be mounted on a short shaft and off center only enough to achieve the desired result. Similar vibrations will be able to be generated by placing a lighter weight on a longer shaft due to the leverage that the extra length of the shaft creates but this is a double edged sword as the additional leverage will also stress the motor bearings/bushes more and shorten its life.

What's Shaking

The project has been a great success and one that has cost next to nothing. Admittedly the capacity of the machine is limited but I can live with that as I will be only cleaning small batches of .223 and .32-20 brass with the odd few .303 and 8x57. On this subject Craig’s mark 2 tumbler consists of a 10 liter paint bucket with his trusty motor fastened to the bottom and works very well and has much better capacity though over heating appears still to be a challenge.

Aside from the obvious saving over buying a commercial model I derived a huge amount of personal satisfaction from the project. It’s a bit like shooting cast bullets. Using something I made myself. Still doesn’t make me any less mean though I guess.

Postscript

Since completion of the tumbler a server fan from a defunct computer has been added to the MDF box. The purpose of the fan is to blow additional air over the electric motor in operation so as to produce constant cooling. This modification was at nil cost (surprise, surprise!) and appears to be successful. Jeff Brown, Email, jeff.brown@clear.net.nz