Thursday, 9 February 2012

Z axis redesign

So the original Z axis wasn't good enough. After dismantling to diagnose, the flexing problem is due to the uneven end of the threaded rod where it meets the motor and the seat for the bearing needs to be more secure. This is relatively easy to fix I think.

The play in the Z axis needs a more fundamental rethink. The original design used a pair of interlocked cages that slid against each other.

After some experimentation, I found that the Technic toothed track part with some medium sized gears can produce a very tight fit, but still move smoothly. Again, the moving part is surrounded by other lego beams giving a smooth surface for it to slide on. It is more compact than my original version.

This is the new design, with a total movement of 17 lego studs. In the following pictures you can see the sliding part in different extreme positions and from different sides; the main negative aspect is that it looks like a sub-machine gun!

Here's a video showing that there is no visible play in any direction:

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