Water vortex exhibit repair gives a look at the bearing and gasket design

[Ben Krasnow's] water vortex machine has been an exhibit in the lobby of the San Jose City Hall for quite some time now. Unfortuantely he recently had to perform some repair work on it due to the parts inside the water chamber rusting.

This is the same water vortex that we saw about a year ago. It uses a power drill to drive an impeller at the bottom of a water column to produce the vortex. That impeller was made from painted steel and after being submerged for eight months it began rusting, which discolored the water. [Ben's] repair process, which you can watch after the break, replaces the shaft and the impeller. He reused a plastic PC cooling fan as the new impeller. The replacement shaft is stainless steel, as is all of the mounting hardware that will be in contact with water. But for us, the most interesting part of the repair is his explanation of the shaft gasket and bearings. Two thrust bearings and two radial bearings ensure that the shaft cannot move axially, which would cause a problem with the gasket. He had intended to swap out the oil seal for an all Teflon seal but the machined acrylic wasn’t conducive to the part swap. Instead, he replaced it with the same type of gasket, but bolstered the new one with some silicone to stave off corrosion.

Comments

  1. Wizzard says:

    Why not use magnetic coupling?? Skip all the seals and such, use some strong magnets and a teflon bottom with a DIY (or extra-strong) stirrer bar.

    Ben, nice work again :) What’s this, number 5 or 6 on Hack-a-Day?

  2. Hackerspacer says:

    You can get higher torque mag drive units. They are common on chemical pumps that will dissolve or react with stainless steel.

    But why use components whose inherent construction is not suitable for the environment in which it is expected to operate? A la steel in water instead of stainless. Why not start with stainless rather than have to fix it all later?

  3. Valen says:

    a handful of floating coloured beads could be an interesting addition, as would some kind of lighting. also I hope the production device uses something quieter than the drill ;->

  4. Mr Name (required) says:

    What astounds me about this story is that someone would build a museum exhibit demonstrating a water effect and _NOT_ use stainless or long-life materials. No wonder so many kids who push demo buttons at museums are left disappointed when nothing happens.

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