Parametric Test Tube / Centrifuge Tube Rack

thingiverse

This is a printable rack designed to hold various sizes of test tubes or centrifuge tubes used in modern biochemistry. The design is highly customizable, allowing users to remix it for any size tube, with up to four rows per rack. All parts of the rack are created to print without supports on an FDM printer, oriented for maximum strength and aesthetic appeal. The shelves slide into the stand uprights smoothly, and there's a tiny bump that registers and locks each shelf in place. If your tolerances are correct, no adhesives should be needed, and the rack can be disassembled if required. When assembling, insert the edge of the shelf without the locking bump into the rails first; it makes the process much easier. For tall racks prone to tipping over when knocked, there are optional 'shoes' that clip onto the 'feet' of the rack stand. These shoes are removable and add extra stability to the rack. Parts are organized into two 'platters', one containing all the stand parts (the sides and shoes) and the other containing all the shelves. Alternatively, you can save the parts individually using the customizer. Three tested variants are provided: * A single-tube rack for 10ml centrifuge tubes, without shoes, intended mainly as a tolerance test (although they're also quite cute). * 1 row of 6x 10ml centrifuge tubes, with shoes. * 2 rows of 7x 2ml centrifuge tubes, without shoes. These are the examples shown in the image. For other sizes of tube or different grid arrangements, you can use the Thingiverse Customizer to remix your own version (the recommended way, so others can benefit from your work) or download the model and use the OpenSCAD Customizer (available in the latest version) to create your own presets. To design the overall rack, use the "assembly" part option, and then use the "platter_stand" and "platter_shelves" options to print the parts in batches. Alternatively, generate each part individually and create your own platter arrangements if needed. The layout is highly flexible; you can have up to 6 rows with different numbers of tubes per row, and even 'stagger' the rows by giving a positive or negative offset. This allows you to create either square or hexagonal packings of tubes depending on whether you want a regular grid for a typical work-bench rack or honeycomb 'storage' racks with maximum possible density and strength. The design accommodates 2 or 3 shelves, with 3 being the default used in all examples. The size of the tube hole is provided for each shelf; usually, the upper two shelves are sized to fit the tube, but the lowest shelf has a much smaller hole where the end of the tube can rest. For tapered centrifuge tubes, the lowest hole should be slightly larger than the end of the tube so it fits snugly. For round-bottomed tubes, this is less critical. Don't forget that holes have a tendency to shrink on FDM machines, so add 0.5mm to 1mm to the actual tube measurement. For tubes without removable caps (or with flanged tops), you might be able to get away with only two shelves, both with larger holes than the tube. In this case, increase the "stand_height" parameter so the lower shelf is further up off the table. Remember that the weight of the tubes will now be borne by the top shelf, not the bottom. It's possible to use only one shelf if you hand-tweak the code, but I don't think it would be very mechanically stable, so it's not a selectable option. In theory, the size of the rack could have been calculated from the tube spacing and number of tubes, but that would make the overall size of the racks difficult to control if you wanted consistent rack sizes for storage of different kinds of tubes. So, the "base shelf size" and "shelf height" are the main parameters to tune the overall geometry of the rack. The rows of tubes are centered within this geometry; don't forget that the stand sides add a couple of millimeters to the total width if you're trying to fit inside a box. I printed my shelves in transparent Polymaker "PolyLite" PETG and the stand sides in black "PolyMax" PLA, mostly because it looked pretty. The PETG shelves are also more heat-resistant than the PLA; however, you shouldn't be using these for high-temperature chemistry with glass test tubes.