Fan-Based Parts Tumbler Is A Breeze To Build

A parts tumbler is a great tool to have around. But if you don’t use it all the time, it’s hard to justify dropping hundreds of dollars on one. Fortunately, there are many ways to make your own tumbler while tailoring it to meet the need. Because really, as long as you get the medium moving enough to abrade the parts, you’re good.

[Daniele]’s parts tumbler is cool because it’s fairly easy to make, it’s really quiet, and it does the job quickly. This tumbler moves the medium by using an imbalanced plastic fan, which [Daniele] created by drilling a hole through one of the blades and fastening a short bolt and nut through it. If you’ve ever tried to stop a washing machine from walking away, you may be thinking this is a strange idea, because now he’s got a 4500 RPM vibration machine scuttling about the shop. So really, the true genius of this build lies in the great pains [Daniele] took to absorb all that vibration.

He’s got the fan float-mounted on rubber-lined springs and rubber mats under the washers involved in connecting the latching plastic box to the fan. Our favorite anti-vibration features are the twist-lock power connector and the custom silicone feet made from Motorsil D and cap bolts. We don’t know what the medium is here, but it’s got us thinking Grape-Nuts might work. Blow past the break to chew on the build video.

The only problem with this build is that this type of fan isn’t cheap, and using it this way will definitely shorten its life.

Not a fan of this type of tumbling? Here’s one that takes your drill for a spin.

EDIT: Many belated thanks to [Baldpower] for the tip!

53 thoughts on “Fan-Based Parts Tumbler Is A Breeze To Build

  1. I’ve broken off a blade of a fan to make it an agitator for etching PCB’s, wired it up to a USB cable so it can be used almost anywhere. It’s no where near as fancy as this is.

      1. The unbalanced fan needs enough momentum to effectively agitate the tumbler material, so I think the bolt ends up being necessary. After all, a feather is sufficient to stir a tub of water, but a tub of gravel isn’t going to budge.

        1. Which I would agree with if the fan housing was rigidly mounted, but it’s on a very flexible mount instead. So the energy that would normally be wearing the bearing will be transmitted through it to the tumbler instead.

          1. The hub design of this type of fan and it’s intended lifespan are very affected by changes to the fan blade ie: chipping, dust accumulation or any other changes that may cause an imbalance. An imbalance was created then given an arm resulting in a considerable increase in vibration that isn’t translated as you describe nor absorbed as you allude.

          2. there’s also the fact that pc fans are cheap and easily salvaged. I wouldn’t be worried of the wear on a part that would probably have gone to the dump anyway.

          3. Inquisite, it’s not the vibration that damages the bearing. It’s because in *normal use*, the bearing is the most flexible part of the entire mechanism, and therefore any net forces result in deformation at the bearing. But in this *specific* case, the bearing is far, far far more rigid than the soft mounting springs, so all the energy goes into bending the springs instead of bending the bearing.

        2. If anything, wouldn’t the wear just widen the bearing’s inner diameter causing the rotor’s shaft to have a looser fit. Meaning it’s going to be less prone to lock-ups, and may introduce considerably more vibration, which was intended in the first place? These computer fans are brush-less and doesn’t necessarily need a tolerances to work. Worse case would be to wear down the bearing enough that the rotor’s walls touch the stators (and even then these fans are robust enough, and even have a couple of millimeters clearance on all sides of the rotor and stator.) I think it’s going to last a long time.

          1. The bearing is a sleeve bearing that relies on a lubricating film. The film of oil centers the shaft by its surface tension and shear-thickening properties while the shaft is spinning.

            When the bearing hole wears loose, the gap between the shaft and the bearing grows and the film of oil no longer forms properly along the shaft. It stops centering the shaft and the shaft starts to roll along the outer diameter. Usually the shaft tilts and grabs one side of the bearing at the top, another side at the bottom, and the whole thing starts to nutate. The centrifugal action of the wobbling rotor then bites the shaft harder into the sides of the bearing and the thing begins to vibrate strongly, chewing out the bearing in a short order. The hole of the bearing gets ground out into a sort of hourglass-shape by the nutating shaft because the motor is trying to turn at a different speed than the shaft can roll around the bearing.

            Old computer fans fail by starting to make this strong buzzing sound. After a while, the friction grows too high for the motor and the fan stops. This is what basically happens to them. If you pick it up, you’ll find that you can tilt the rotor from side to side a little: it wobbles in the bearing. You can center it and it runs fine for a while, and then suddenly goes “HRNGGNNNNN…” again and stops.

          2. Point being that since the fan rotor is never perfectly balanced, if the bearing didn’t hold it straight it would eventually wobble out of control. The magnets in the motor suspend it axially, but they’re not strong enough to keep the axis pointing straight, so the bearing has to do it.

            When you deliberately put the rotor off-balance like this, the bearing sees hundreds of times the normal loading, and the lifespan of the bearing drops from the usual 50,000 hours to maybe 500 hours. That’s just a guess, but I wouldn’t expect it to run longer than 2 weeks in continuous use.

            That may be fine for this application, because the device is meant for hobby use. It sees a couple hours of use per week or month. In production use, it wouldn’t last.

          1. Yes, but they have bearings on the two ends of the unbalanced shaft. At least the quality ones do. Some just have a cheap DC motor with a piece of metal fixed to the shaft. Computer fans have a single sleeve bearing doing double duty – it’s just not designed for the kind of work.

            And I’m no stranger to vibrators either. Don’t be confused by the pseudonym; I’ve burned out a couple and that’s why I know how they’re built.

        1. If it has two ball bearings like most of the professional fans with die cast frames do it will last a very long time.
          A cheapo “quiet” consumer quality fan with sleeve bearings will die quite quick, tho.

      1. Does anybody in the hacker community buy new fans? Absolute everybody I know has crates full of used ones. You scrap one server rack or one cinema-DLP-projector and you have enough fans to last you at least a year…

        1. When I am trying to build something nice, something that will operate where I am listening to music, watching video or sleeping I choose to buy new fans that are rated for low db.

          For anything else.. yah, dusty old beasts pulled from some ancient computer long ago are the only way to go.

          1. Quality fans will remain silent after ages. I’ve taken metal Papst Motoren fans from appliances made 40+ years ago which are still silent today.
            Current PC fans, including all branded ones (corsair, thermaltake etc.), are absolute junk in comparison.

  2. Hundreds of dollars for a vibratory tumbler? Everyone from Horrible Freight to Lyman can beat that price. Including a new converted cement mixer. Even ultrasonic cleaners are cheaper.

    1. Yeah it’s quite an overstatement. We’ve seen plenty basic rotary tumblers on Hackaday. The design of this one is interesting on its own though, and uses dirt-cheap spare parts.

  3. I wouldn’t use a brand new Sunon fan for this, but like many here (probably), I have a tote full of old PC case fans I salvaged because they “might be useful one day”.

  4. to the point of lifetime – double-bearing fans should be able to cope with that for a certain amount of time. think of crankshafts…… some of which are only single-sided held in bearings in model-engines. if you use cheap fans with only a single sided (plastic?) sleeve bearing you will run into trouble soon

  5. I watched this yesterday but for many of the reasons shared above re the fan question the longevity.
    Time taken to build plus reliability factor.
    Verses a $15 palm sander upturned and similar container bolted. Faster to build and faster to work.
    Polishing off rusty bolts, it doesn’t need to look for clean and likely wont after much use.

  6. The link to the fan (goes to Digikey) is for a ball bearing fan which should hold up to the vibration better than other styles, except that he’s got it mounted horizontally and ball bearings are meant only for vertical installations. A brass sleeve bearing should also hold up to this reasonably well, but a nylon sleeve bearing won’t last long at all. Sleeve bearings are also meant for vertical installation. Fluid dynamic bearings are just fancy sleeve bearings. What is needed here is thrust bearings, but good luck finding a fan with those. Certainly any true hacker should have a giant box filled with old, salvaged, (effectively free) computer fans. Just keep using those unless swapping it out is complicated and time consuming. Shouldn’t be in this case.

    1. The orientation doesnt matter because the axial load of the rotor is supported by the magnetic field of the motor. It doesnt add any load on the Bearings if you mount a fan of this type vertically.

  7. I assume this is a 10$ fan, and the replacement time is under 5 minutes. If the run time on this piece of equipment is 600 hours (total random guess) of total operation before catastrophic fan failure (because that is likely what dies on this device), that works out total estimated time before failure is
    = 200 3-hour cleaning events (600/3).
    = 25 24-hour cleaning events (600/24)

    How often does he need to use a vibrator to polish his brass knobs?
    Also, how well does this polish rocks?

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