3D printed gel combs

One of the ideas out there in the “3Dprintosphere”, is that seemingly common plastic doo-dads are way too expensive, and would be a lot cheaper if they could be custom fabricated on-site.  A classic example is gel combs – those little plastic things we all use to form wells in our SDS-PAGE gels. For the privilege of owning one of these small pieces of plastic, a reputable manufacturer of such mini-gel apparatus will charge $37 for a pack of 5. Add in shipping costs and you’re looking at $10 a pop, for something that costs maybe 10c to make.

So, SketchUp, Repetier, and PrintrBot to the rescue…

GelComb

That’s a custom 7-well 1.5mm comb. The reason we did this is to load more sample.  A regular 10-well comb has 10mm deep wells, 5mm wide, so they hold ~75μl each. These wells are 12mm deep and 7mm wide, so they hold 126μl each (previously we had to use tape to join together 2 wells of a 15 well comb to make a wide lane).

This one was printed at 0.15mm layer height using MakerBot PLA filament at 225C with solid rectilinear infill. It took about 10 minutes to design and 16 minutes to print, and uses about 900mm of filament, so assuming a cost of 13c per meter** that’s a 12c material cost. If it breaks or wears out, who cares?  We could print a brand new one every month for 6 years still be ahead on cost. And we can customize the size for whatever sample is needed.

The STL file for this, plus those for standard 10 well and 15 well combs (for the mini-gel box maker known as “big green”), are in this zip folder. I also threw in the Sketchup file with a blank comb-body so you can draw in the lines and use the push/pull tool to design custom well sizes, as we did here for the 7 well version.

Enjoy.

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**PLA density = 1.24kg per liter
A 1kg roll costs ~$45 depending on where you source it
Diameter=1.75mm, radius 0.875mm, pi R squared and all that malarky, so 1 meter = 2.405 cm3
This 2.405cm3 weighs 2.982 grams.
So a 1kg spool has 335 meters, i.e. 13.4c per meter