Alternative Encoder Idea

Technical Details
21

A ‘traveller’ allows a device to travel along a fixed path, following its source and tensioning it.

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In the case of a yacht, it is moved and fixed in place, but it can travel freely in a Maslow iteration.

22

Using a motor and roller chain to move the traveler across the track would be easy enough, but motorizing the tensioner between the traveler and the sled poses some problems.

23

The traveller is passive. It just follows the sled while exerting the vertical force that the massy bricks do.

24

Problem with the traveler idea is multifold sadly.

  1. The tension would be lowest at the bottom of the workpiece and highest at the top
  2. It would add an opposing force to horizontal movement (there needs to be some lateral force before it would follow) which would make accuracy at the bottom corners worse where the near chain is closest to vertical.
  3. its effectiveness in keeping the sled in contact the with the material will be proportional to the distance from the bottom due to angles and leverage.

I’ve seen a couple of ideas using tensioning cords at the bottom but I really dont see it working as a passive system. If it was active using chains and additional stepper motors then yeah, 2 motors in opposition would eliminate a lot of chain sag, the maths is pretty simple as diagonally opposite motors would use the same calculations with a different origin. But this means twice the cost for motors, chain and a significantly bigger motor controler board for 5 motors (4 corners + Z)

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