Kossel Slide Carriage Alignment tool

I noticed there is lack of tools for aligning Delta printers. We are instead relying on the quality of the print and a prayer for getting the geometry correct. I would like to standardize on a set of tools for validating the physical geometry of deltas is correct. This is the first tool.

This is a concept tool for aligning the Slide Rail carriages on a Kossel Mini. The carriages need to be perfectly parallel to the towers (or slide rails). The mounting holes allow of a small bit of play which can allow the guide rod mounting to not be square with the towers. This directly translates to effector twist. Effector twist will cause a whole host of issues but moist notably poor layer adhesion at extremes and skewing of the print at different points of the bed. You want to minimize effector twist although it can never be 100% eliminated.

How to use:
With the belts removed, the carriage is moved to the bottom of the guide rail.
A 400mm piece of 3.2mm diameter music wire is inse