| With the cover very carefully removed, you can see the remarkably simple working parts of the Mikrokator. The dial indicators we saw earlier all had multiple gears and slack-removing mechanisms, but there’s no way such complex mechanisms could be made to work at the level of sensitivity this thing possesses. It almost has to be simple because there’s not enough movement going on to drive anything complicated. The heart of it is nothing more than a twisted ribbon.
A very thin spring bronze ribbon is twisted in opposite directions on either side of the little ball of glue that holds the pointer. When the ribbon is stretched even a tiny bit it untwists by an amount that is accurately, linearly proportional to the amount of stretch. The metal of the ribbon is not getting longer, just adjusting to occupy a longer space by allowing the twists to unwind.
When the ribbon twists and untwists, it moves a very fine glass fiber. The fiber is so thin that it’s nearly invisible with the cover on. When I first got this thing, I wondered how they made the pointer end fly through the air with nothing holding it!
The pointer is just a drop of paint on a flattened section of the glass fiber. It must be so delicate! When the probe tip below is moved, the pointer end moves by about ten thousand times as much. In other words the “gear ratio” between movement of the tip and the pointer is about ten thousand to one. |
