Adjustable Volume Straw Pipette

by kwalus, published

Adjustable Volume Straw Pipette by kwalus Mar 23, 2013

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47640Views 3772Downloads Found in Learning


This is a simple adjustable-volume straw pipette. It should be very useful around any wet lab and works nicely with a relatively high range of possible volume settings. You can calibrate the volume but it is generally only good for low precision work. The pipette has two thumb nuts for adjusting upper and lower stops.

To complete the build you will also need a spring (Pez dispenser) but it may work without as the membrane is elastic, a kids balloon, drinking straw, and some tape. Good luck!

See a demo: http://youtu.be/N2Ax4OGokGM


Print the upper body, lower body, plunger, and two thumb gears. You will need a spring, which I got from a kids Pez dispenser for its form factor. The balloon membrane is elastic so you may get away without the spring but it is nicer to have it. You will also need a balloon, some tape, and a straw. It is designed for one particular straw diameter but I can upload others if there is demand. See the attached photos for assembly steps. I printed all the pieces at 0.1mm with 15% fill and 100% fill for the plunger.

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Many thanks for this idea!! It is very useful for education and with only a few modification for nedical uses. Please more of such good labware. :-)

it would be very helpful if you provided an assembly video.

Thank you for that simple and usefull tools.

So when this is all together, does the liquid reach up to the balloon?

no, it should not even go most of the way up the straw.

Perfect! And sorry for what is another silly question...but what diameter of straw is this set for..?

Solidworks tends to do some funny things with its default settings for the X, Y, and Z axis. I use Solidworks and Autodesk Inventor. Usually, solidworks orients things such that the Z axis is horizontal by default.

These will print better if the part is reoriented relative to the X, Y and Z axis. I have done this with the STL's I downloaded. If you want the modified STL's, please contact me.

Could you please post a version of the lower body with no logo on the bottom? I am having an issue while printing it with it staying in place on my print bed.

This would be incredibly useful for my molecular gastronomy! Thank you!!

this could lead to 3d printing useful medical devices :)

Working on it!

do you mind if i ask, 1) what software did you use to design this, and 2) how did you get the logo on the casing?

I used SolidWorks to CAD this, it's my favorite tool by far. I also have a Solidworks file for the logo and combining the two is very easy with that.

thanks. I'm trying to figure out how to upload existing 2d images that can be extruded based on their lines via sketchup. and ideas?

This is really cool. Thanks for this.

Can I ask if you needed support on any of these structures. Looking at the upper body it seems as if it would be required but I have had very bad results trying to remove support from internal structures.

If you print this way the inside surfaces that are rough from unsupported bridging don't matter in the end.

I printed all parts without support using 0.1mm PLA. I made several prototypes and in each case it worked without support. The upper body is printed with the top side down, and the bottom body is printed with the bottom (narrow part) down.

Thanks - I will try without support

Thanks it was fun!