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Z Yoke and kinematic bed mounting - Part 1

A project log for MechaCore - Railcore Inspired 3D Printer

I started to build a RailCoreII ZLT printer, but decided to give it a once-over and fix/update everything I don't like, keeping what works.

patrickPatrick 11/13/2019 at 07:540 Comments

SLooking at the Z Yoke design, which is about the same for printed and CNC metal, there is certainly room for improvement. 

The linear rail car is constrained from any rotation and linear translation in the X & Y, free to move up & down on the Z. The lead screw provides Z positioning. Below shows the linear constraints (red) rotational constraints (blue) and the primary force path from the lead screw nut to the bed holding interface.

The challenges here

  1. Yoke to linear rail carriage is only positionally constrained by the screws. 
  2. Lifting force from lead screw is loading the lead screw nuts in tension, loose screws will affect the height
  3. Method of bed mount is sub-optimal, not really allowing for misalignment and will have binding issues unless there is excessive clearance, which could cause bed movement

My plan:

This is the direction I'm heading, although this will take a bit longer to get to where I want it to be.

Concerns I have at the moment

Discussions