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I previously worked on Virtual Reality and other hardware at Valve.  I currently work at Google[x].

Prior to starting at Valve, I built computer peripherals such as keyboards, mice, and joysticks that were designed to be used inside MRI machines.  My company, Mag Design and Engineering, sold these devices directly to researchers at academic institutions who used them to publish scientific papers in peer-reviewed journals.

After work, I spend time on many different types of projects that usually involve circuit design, machining, material selection, and general fabrication/hacking.  My favorite place to be is my home workshop.

ben dot krasnow at gmail

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Saturday, August 13, 2011

Water vortex display from SJ City Hall exhibition -- repair and upgrade




I built this project a few years ago with a friend to help get him interested in mechanical design. Later, the project was adapted for display at a "tech and art" exhibition at San Jose City Hall. After 8 months, the painted steel impeller began to rust and discolor the water in the tube. I took the device back to my shop and replaced the original aluminum shaft with a stainless steel shaft, replaced the shaft seal, and changed the impeller to an all-plastic design. If I were designing the device again, I would opt for a spring-loaded PTFE (Teflon) shaft seal, which I have used with great success in other applications.

Drill motor control:
http://www.youtube.com/watch?v=7yEABsNyRfo

Original video showing the WiFi-controlled watering can and vortex tube:
http://www.youtube.com/watch?v=XKrlRJ-GJms

6 comments:

  1. Do you think the plastic fan blades will handle the stresses involved?

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  2. Have you thought of using a water additive for the algae? Foaming could be an issue but I think some formulated to handle that.

    Baring that, maybe a good steam flush with some distilled water would work. Don't use alcohol what ever you do (you probably already know that), it will craze the acrylic.

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  3. Andrew, I think so. If not, I'll probably be making another post about it.

    Anonymous, yes I used a fountain additive to prevent algae. I think it might have accelerated the corrosion on the the original steel impeller.

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  4. clorox works good as an additive

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  5. For future projects one may want to keep in mind water pump seals. Generally the seal surfaces are, ceramic to ceramic, and will last a long time with only water for a lubricant. Any corrosion prone metal parts are kept on the dry side of the seal assembly.

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  6. I know I'm commenting on a really old post, but I had an idea for your seal problems. You could use a magnetic coupling between the motor shaft and impeller. This way you could avoid having seals altogether since the magnets would be able to transmit the rotation through the base of the container without piercing it.

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