Centrifuge Spins Samples Up To 400g

We were curious to see when someone would use a 3D printing pen for something other than art. It might not look very pretty, but [Techmeology] “drew” this centrifuge mount for a motor in order to spin some test tube samples.

It’s kind of hard to see in the picture, but the test tube holder “arms” are detachable, and when the motor spins up it opens like an umbrella. Pretty much all the parts are recycled, and the motor came from an old appliance, making the cost of this project negligible — a good use case for any remote location that might require custom parts or repairs.

As for actually fabricating functional items with the 3D printing pen, [Techmeology] offers some useful tips for drawing brackets on his site. For instance, wrap the parts for which you need mounting brackets in paper. This provides a barrier while drawing your design in molten plastic.

There are a few other tricks that can be performed by 3D printing pens, like using them to “weld” parts back together. If you don’t already have one you could just use a soldering iron for this purpose — or make your own 3D printing pen using LEGO and a hot glue gun.

19 thoughts on “Centrifuge Spins Samples Up To 400g

          1. If the 40Kg estimate is correct, I agree with RÖB. I have dealt with 3D printed parts extensively. I can’t see a 3D printed part of this quality holding that load.

          2. Okay guys, “g” is a terrible unit when it comes to how much force something can take. When people think gs, they think about how much force a “g” is for a person. One “g” for a 75kg person is about 750N, 75kg-f, or 165 lb-f, and 400 “g”s on a 75kg human is some absurd quantity, 300 kilonewtons, about 30 (metric) tonnes, which is and absurd amount of force. At this scale, 400 “g”s for a 5mL test tube (guesttimate) with 5g of solution, say 5g of test tube (overestimate) gives us maybe 10g. Suppose it’s all on the outside, somehow, magically. 400 “g”s on that, (10m/s^2 * 400 “g”s * 10g) is 40 newtons, or 9 lbf. Actually, that’s not terribly large, but it’s not terribly small either. I’d be wary of its long term reliability. But the numbers do work out to 400gs. The actual force on it is dependent on the weight of the load, which can be quite small give that it looks like a pretty small test tube.

          1. I think that is where the maths went wrong. The radius in the formula mentioned is the radius to the centre of gravity and not the total (maximum) radius of the rotating part.

  1. If you were to fill the test tube about 1/2 to 2/3 of the way full of water the offset weight would easily be five grams or more. Even though a lot of it won’t be at the farthest point of the radius, you could easily get a 3 pound offset load at full speed. I believe it can generate the forces claimed, I just don’t think it can hold it long.

  2. Man when I have used 3D printers they have been safely in a fume hood. They probably aren’t terribly bad for you but they certainly aren’t super healthy either and man do they stink.

    I don’t think I’d want to sit there manually doodling that thing out :P

        1. PLA itself is likely safe, even if you are inhaling a so-called nano-spay (couldn’t find a reference on google, so I’m assuming its similar to ultra-fine dust) since it eventually degrades into lactic acid. That’s why it can be used in temporary medical implants.

          The big unknown is the dye’s and colors the manufactures use, and any other potential additives.

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