Delicious Liquid Nitrogen Science

Today I planned to visit the newly opened “The Village Workshop” in Northville, MI for 3D printing some parts. It is really awesome facility to have in the neighborhood for every maker.

While waiting for 3D printing assistance at the entrance, I bumped into a demonstration by Willie from Kold Ice Cream. Both me and my daughter were stunned to see fumes of liquid nitrogen on the table.

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Willie was dropping liquid nitrogen on the hands, serving snacks dipped in it which was more fun to see exhaling cold fumes. He offered us a neat explanation behind cold nitrogen boiling at room temperature with boiling point of -196 deg C and turning into vapors. Though it is dangerous to leave your fingers for longer period in the liquid nitrogen, Willie seems fine dropping liquid nitrogen on hands and his shirt.

He showed me and my daughter some cool stuff, like starting fire and then extinguishing with nitrogen fumes and liquid. Too much liquid nitrogen around the flame stops it due to lack of oxygen nearby.

Most important part for my daughter was the liquid nitrogen ice cream preparation. It turned out that it was best ice-cream she ever tasted.

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Delicious science study was really cool for all the kids visiting the workshop today. I hope it attracts them to creative developments in STEM field.

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Dollhouse Fan – 3D Print

My daughter asked me several times to create a dollhouse fan. In the past, I did use CAD software, but mainly for simulation and never created any complete product up to manufacturing. So this was a daunting task to create a small dollhouse fan right from scratch in CAD software.

CAD model of the assembled fan looked nice.

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I printed the CAD model on Shapeways in flexible plastic (Nylon) dyed in Pink. For my daughter, Shalvi, everything has to be Pink. It was quite cheap, costing shipping more than 3D print.

Post-production: 

When 3D print arrived, it looked really cool except the lots of powder left in the motor holder shaft. Obviously, I missed providing more than one escape hole for blowing the nylon powder. I cleaned up the remaining powder manually.

For motor, I used a nice and cheap helicopter rotor motor from dx.com. It fitted perfectly to the designed motor holder. Motor wires were passed through the motor holder hollow pipe for connecting to a small battery cell. Hole in fan was smaller than designed in CAD, which came as a surprise. I tried drilling, but material was too tough for that. After repeated attempts, I was able to increase fan hole slightly and finally used gorilla glue to hold the shaft in place.

Here are some of the pictures after it arrived and assembled.

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Even with small battery cell, fan runs really fast. Next iteration will be to include even smaller battery and completely enclose the motor inside the motor holder. It was nice project for me to design for 3D print and assemble the fan.

If you like this work, please cast your vote for this fan for 3D printing competition on Instructables.