message: updated step files for 1.6
diff: ![Rendering](rendering_1_6.png)
  -[Exported step file](exhaust%20pinch%20valve%201.5.step) of version 1.5 is available here for download.
  -
  -### Changes since last version
  +### Latest changes
  The stop is moved down by 3 mm, which should buy us a lot more leverage.
  The stop is now flat. We might need to tweak exact dimensions further to get a perfect close, but this should be better.
  Watching the video I'm pretty concerned watching that stop flex. I made it run the full width, I made it thicker, and I also bulked out the tube holders.
  Bearings are now better aligned with the tube.
  -Latest progress on 3d-printed part design (v1.6) is found in
  -[OnShape](https://cad.onshape.com/documents/3fe0c1f79c482144c267173d/w/2ad1c08071a25185f9c78c68/e/764ab1c89ba2f5ce8cf4b650).
  +v1.6: Broader shelf, slightly larger bump
  +
  +### Exported step files
  +- [base](exhaust%20pinch%20valve%201.6%20-%20base.step)
  +- [rotor](exhaust%20pinch%20valve%201.6%20-%20rotor.step)
  +- [bearing](exhaust%20pinch%20valve%201.6%20-%20bearing.step)
  +
  +Original design found
  +[here](https://cad.onshape.com/documents/3fe0c1f79c482144c267173d/w/2ad1c08071a25185f9c78c68/e/764ab1c89ba2f5ce8cf4b650).
  ## BOM
  