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Adjustable Volume Straw Pipette

by kwalus, published

Adjustable Volume Straw Pipette by kwalus Mar 23, 2013

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Description

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: youtu.be/N2Ax4OGokGM

Recent Comments

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

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

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

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Instructions

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.

Comments

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DoctorWoo on Mar 25, 2014 said:

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

kwalus on Mar 25, 2014 said:

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

3dbotic_com on Oct 9, 2013 said:

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.

Rubidium on Sep 14, 2013 said:

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.

tombielecki on Jun 18, 2013 said:

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

franciscoAzevedo on Apr 2, 2013 said:

very nice

idolcrasher on Mar 29, 2013 said:

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

kwalus on Mar 29, 2013 said:

Working on it!

nickdisney on Mar 28, 2013 said:

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?

kwalus on Mar 28, 2013 said:

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.

jrombousky on Mar 25, 2013 said:

This is really cool. Thanks for this.

Framingr on Mar 24, 2013 said:

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.

kwalus on Mar 24, 2013 said:

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

kwalus on Mar 24, 2013 said:

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.

Framingr on Mar 23, 2013 said:

Amazing.

feststoff on Mar 23, 2013 said:

Wow! Great work!

kwalus on Mar 23, 2013 said:

Thanks it was fun!

steeve_becker on Mar 23, 2013 said:

Excellent job !

kwalus on Mar 23, 2013 said:

Thank you!

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