Stackable vial racks (parametric) for space management

We conduct research in a relatively small university laboratory, so efficient use of limited space is essential. We use glass vials for all sorts of purposes such as storing compounds, solutions and especially for crystallization experiments. Recently, we have run out of space for storing vials in wooden vial racks with drilled holes, as the number of homemade compounds is constantly increasing. In addition, the number of crystallization setups, each prepared in a separate vial, is growing exponentially because crystallization can take several months and the best way to succeed is to try many different conditions. 

As a result, it was necessary to stack the vial racks, but the wooden racks were not made for this purpose. We have therefore designed properly stackable vial racks for the three main vial types used in our laboratory. 

The racks are compatible with the following vials (diameter x height, measured with cap):
 

• 12 mm x 33.5 mm GC vials (exact size: 11.67 mm x 33.45 mm) 
• 20 mm x 57.5 mm vials, mainly used for crystallization (exact size: 20 mm x 57.45 mm)
• 27 mm x 52 mm vials, used for solvent removal with a rotary evaporator and for compound storage (exact size: 27 mm x 51.90 mm)

There are four versions with slightly different vial hole diameters to find the best working hole size for your printer setup and purpose:

• 12 mm vials: 12.5 mm, 12.25 mm, 12 mm and 11.75 mm
• 20 mm vials: 21 mm, 20.5 mm, 20.3 mm and 20.2 mm
• 27 mm vials: 28 mm, 27.5 mm, 27.3 mm and 27.2 mm

For example, we use a 20.3 mm vial hole diameter to hold our 20 mm crystallization vials so that they fit very tightly to minimise shaking and vibration of the setups when the rack is moved.

For each type of vial rack, 2x2 prototypes are available with different preset hole diameters to quickly determine which is the optimum version. 

The prototypes for the two larger vials include a label inside the holes, whereas the small holes for GC vials do not allow this. In this case, these values and other measurements can be found in the pdf files provided for each model.

The pillars for stacking the racks need to be inserted into the top holes with some glue. We choose this option after we faced issues with breaking pillars if they were printed in place with the rest of the box due to their printing orientation in the z-axis.

The holes at the bottom are slightly wider than the pillars so that they can easily be stacked properly, and they have a 45° chamfer so that interlocking with the pillars (also with a 45° chamfer) works well.

Our print settings for fast printing are:

• Material: PLA
• nozzle diameter: 0.8 mm
• layer height: 0.3 mm
• line width: 0.8 mm
• wall thickness: 1.6 mm
• top/bottom thickness: 1.2 mm
• infill: 12.5 % gyroid
• Print speed: 35 mm/s - 40 mm/s (I am sure a faster print speed also works. I just like to print slowly with less noise. The 2x2 prototypes allow you to verify that the print will work with your desired settings.)
• no support needed due to 45° chamfers

We also find it very useful to use a single color for each co-worker's vial racks, as this color coding allows everyone to quickly identify whether a rack belongs to them or someone else.

In addition to the four versions, the parametric FreeCAD files are also included so you can easily adjust the vial hole diameter, box size, number of vial holes, and pillar height for your specific vials. A few beginner level FreeCAD YouTube tutorials should be enough to modify the racks to your needs, as the design is simple and straightforward. Please feel free to contact us if you need any help.

We hope you enjoy this gadget and that the racks make your daily lab life a little easier.